Black & Decker Codes for Homeowners 4th Edition - Current with 2018-2021 Codes

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Building Design & Safety

One of the most important reasons for building codes is to promote the health and safety of building occupants. Health issues involve topics such as minimum room size, minimum ceiling height, and requirements for removing moisture and fumes that could damage your home and make you sick. Safety issues involve topics such as the size and location of emergency escape openings, design and construction of stairs (one of the most dangerous areas in a home), and the location and installation of smoke and carbon monoxide alarms.

This chapter will help you understand building code requirements that you may encounter when doing projects such as adding rooms and remodeling basements and attics. While this chapter will help you avoid the most common health and safety code violations, it does not address all code requirements. You should refer to other sources for more information before tackling complex projects.

• Stairways

• Emergency Escape Openings

• Egress Doors

• Exterior Doors

• Door & Window Hazards

• Ventilation & Exhaust

• Smoke & Carbon Monoxide Alarms

Habitable Rooms

Habitable rooms (also called habitable spaces) are living, sleeping, eating, and cooking rooms. Bathrooms, toilet rooms, closets, hallways, storage, and utility rooms are not habitable rooms. Habitable rooms have their own set of requirements for size, ceiling height, heating, lighting, and ventilation. Rooms that are not habitable do not have these requirements.

2. You may have obstructions that are at least 76 inches above the finished floor in a basement containing habitable rooms and hallways.

3. Provide at least an 80-inch-tall finished ceiling height in a basement that does not contain habitable rooms or hallways. You may have obstructions that are at least 76 inches above the finished floor in these basement areas. Use these basement areas only for mechanical equipment and for storage.

4. Provide at least an 80-inch finished ceiling height in bathrooms and laundry rooms. This does not mean that all of the bathroom must have an 80-inch-tall ceiling. The ceiling height above sinks and toilets may be less than 80 inches high but must be high enough to safely use the fixture. How much less is subject to interpretation by the building inspector.

5. Provide at least an 84-inch-tall finished ceiling height in habitable rooms with a sloped ceiling. Provide this ceiling height for at least 35 square feet of the finished floor area. Do not count any area with a ceiling height less than 60 inches toward the minimum 70-square-foot habitable room floor area.

2. You may provide a shower with a finished minimum dimension of at least 25 inches if the finished area is at least 1,300 square inches.

3. Provide a shower compartment entry opening of at least 22 inches finished width.

4. Swing hinged shower doors out from the shower stall. Hinged doors may swing into the shower stall if they also swing out. Sliding shower doors are also allowed.

Fire Separations

Doors in a garage wall may not open directly into a bedroom. You also may not install pet doors or other openings in doors or walls from a garage into the home unless the pet door or opening is listed to maintain fire separation. Install self-closing hinges on doors between the garage and the home.

Maintain the same fire separation for drywall penetrations, such as attic scuttle holes, pull-down attic stairs, gas vents, and plumbing pipes, as provided by the gypsum drywall. Most pull-down attic stairs interrupt the ceiling fire separation, because the panel to which the stairs are attached is thin plywood. Seal penetrations between the garage and the home, such as pipes and ducts, with materials that resist the free flow of fire and smoke. Such materials include fire-resistant caulk.

Stairways

Interior and exterior stairways are regulated closely by most codes because they are inherently very dangerous parts of a house. Many of the regulations deal with lighting issues, including the type and location of fixtures and switches. The size, grippability, and location of handrails and railing balusters also account for much of the regulatory wording on stairways. Regulations for interior stairways also apply to exterior stairways. They include riser height, tread depth, and handrails and guards. It is important to comply with exterior stairway regulations, because they are used when wet or covered with snow and ice.

NOTE: A foot-candle is a unit of light measurement approximating the amount of light you receive from a birthday cake candle when it is held 12 inches from your eyes. Photographer’s light meters may be used to measure foot-candles.

You must locate a switch for interior stairway lights at the top and bottom of all interior stairs with at least six risers. Only one switch is required for interior stairs with fewer than six risers. Locate all stair switches so they can be used without climbing any steps.

2. Provide a finished stairway width of at least 311/2 inches at and below the handrail for stairs with one handrail and at least 27 inches at and below both handrails for stairs with two handrails.

2. Do not exceed 3/8-inch finished riser height difference between any two risers in a flight of stairs.

3. Do not allow open risers to fit a 4-inch-diameter sphere for passthrough. This includes interior stairs and exterior stairs, such as stairs for decks and balconies, but does not include spiral stairs.

4. Do not include the height of carpets, carpet pads, rugs, and runners when measuring riser height.

2. Do not exceed 3/8-inch finished tread depth difference between any two treads in a flight of stairs. This does not apply to consistently shaped winder treads contained within the same flight of stairs.

2. Do not exceed 3/8-inch finished tread nosing depth difference between any two treads for all treads between two stories, including at floors and landings. Note that this differs from the tread and riser maximum difference. The tread and riser differences are for a flight of stairs, and the nosing depth difference is for all treads between two stories.

3. Do not exceed 9/16 inch for the curvature radius of a tread nosing, and do not exceed 1/2 inch for the bevel of a tread nosing.

2. Provide a finished winder tread depth of at least 6 inches at any point on a winder tread within the finished width of the stairway and at least 10 inches at the walkline.

3. Do not exceed 3/8-inch finished tread depth difference between any two treads in a flight of stairs measured at the walk line.

4. Do not compare the depth of winder treads to the depth of rectangular treads in a flight of stairs if: (a) the winder treads all have a consistent shape, and (b) the winder treads comply with the winder tread depth requirements. Winder treads will not have the same depth as the rectangular treads, so the winder tread depth will not be within 3/8 inch of the rectangular tread depth.

2. You are not required to provide a landing or floor at the top of interior stairs, including stairs in an attached garage, unless a door swings over those stairs. This means you may terminate a flight of interior stairs directly into a door if the door swings away from the stairs.

3. Do not exceed 151 inches vertical rise of a flight of stairs without providing a landing or a floor. Example: do not install more than twenty 73/8-inch-high risers without an intermediate landing.

4. Make rectangular and square landing widths at least as wide as the stairway. Example: if the stairway is 36 inches wide, build the landing at least 36 inches wide.

5. Make rectangular and square landings depth at least 36 inches, measured in the direction of travel.

6. You may make landings with shapes other than rectangular or square if: (a) the depth of the landing at walk line is at least as wide as the stairway and (b) the total area of the landing is at least as large as a 1/4 circle with a radius equal to the required width of the landing. The walk line is 12 inches from the narrow side of the landing. The area of a circle is 3.14 multiplied by the circle’s radius squared. Example: the minimum area of a curved landing serving a 36-inch-wide stairway is calculated (36 in.2 × 3.14) × .25 = 1,017.9 square inches.

2. Provide a guard at raised walking surfaces more than 30 inches above an adjacent interior or exterior surface. Areas that require guards include porches, balconies, decks, hallways, screened enclosures, ramps, and the open sides of stairs with a total rise of more than 30 inches.

2. You may exceed the 38-inch maximum height where a handrail connects with a guard to provide a continuous structure. Example: a handrail connects to a guard at an intermediate stairway landing. The handrail height at the beginning and ending of the intermediate landing guard may exceed 38 inches high.

3. Provide guards at least 36 inches tall at raised surfaces other than the open sides of stairs.

4. Provide guards at least 34 inches high on the open sides of stairs. Measure the guards vertically from the nosing of the treads.

5. Limit the height of guards that are also handrails to not more than 38 inches. The IRC does not limit guard height other than for handrails.

2. Begin and end all handrails with a newel post, volute, starting easing, or starting newel.

3. Project handrails at least 11/2 inches and not more than 41/2 inches from any adjacent wall.

4. You may interrupt a handrail with a newel post at a turn.

5. Provide continuous guards for open sides of the entire flight of stairs, even if some of the flight is less than 30 inches above an adjacent surface.

6. You need not provide a guard if the entire flight of stairs is less than 30 inches above an adjacent surface. This applies even if a lower flight of stairs connects with an upper flight of stairs at a landing. Example: a landing occurs before the last three risers of a stairway. The last three risers are a separate flight of stairs and do not require a guard or a handrail.

2. Use material with a perimeter dimension of at least 4 inches and not more than 61/4 inches and a cross-section dimension of not more than 21/4 inches for Type 1 non-circular handrails.

3. Provide Type 2 handrails that have a perimeter dimension greater than 61/4 inches with a graspable finger recess on both sides of the profile.

4. Apply handrail shape requirements to interior and exterior stairways, including stairways for decks and balconies.

2. Do not allow stair guard openings, such as balusters, to pass a 43/8-inch-diameter sphere.

3. Do not allow openings under stair guards formed by a riser, tread, and the guard’s bottom rail to pass a 6-inch-diameter sphere.

Emergency Escape Openings

An emergency escape and rescue opening, commonly called an egress opening, is required in all bedrooms and in most basements. Codes are very specific concerning the minimum clearances of the openings and how they can be accessed, as well as how they can be exited from the exterior. Rooms that are not intended for sleeping typically do not need to meet egress requirements. You may use an operable window or a side-hinged or sliding door as the escape opening.

2. Provide at least one escape opening in most basements. You are not required to provide a basement escape opening if: (a) the basement area is not more than 200 square feet and (b) the basement is used only to house mechanical appliances.

3. Provide each basement bedroom with an escape opening. You are not required to provide other escape openings in basements in addition to the bedroom escape openings.

4. Open all escape openings directly onto an area that leads directly to a public way. This means that escape openings cannot open onto an enclosed courtyard or onto a similar area that does not lead directly and without obstruction to an area that is accessible by the public.

5. You may open an escape opening under a deck or porch if: (a) the escape opening can be opened to the full required dimensions and (b) the space under the deck or porch is at least 36 inches high.

6. Note that an escape opening may be required when converting a previously unfinished basement into finished space, especially if the finished space is a bedroom. Verify requirements with the local building official.

2. Provide each escape opening with a clear opening at least 24 inches high and at least 20 inches wide.

3. Locate the sill of each escape opening not more than 44 inches above the finished floor. Measure the sill height from the finished floor to the where the clear opening begins (the bottom of the opening).

4. Measure escape opening height and width using the clear opening area, which does not include obstructions, such as window frames.

NOTE: If the window opening is the minimum in both dimensions, it will be too small; at least one dimension must be more than minimum to meet the code requirement.

2. Provide each well with at least a 9-square-foot clear opening area and a depth and width of at least 36 inches in each direction.

3. Install a permanent ladder if the well bottom is more than 44 inches below grade. Ladder rung specifications include: a rung width of at least 12 inches, a rung projection of at least 3 inches from the well wall, and a rung vertical spacing of not more than 18 inches apart. A ladder may encroach not more than 6 inches into the minimum well width or depth dimension.

Egress Doors

The egress door opens to the outside and meets all egress door requirements for accessibility and opening size. Every dwelling must have at least one egress door. The egress door is usually the front door. Other exterior doors need not comply with the egress door requirements.

2. Install a side-hinged egress door that provides a clear opening at least 32 inches wide and 78 inches high. Measure door width between the face of the door when open to 90 degrees and the outer edge of the door stop. Measure door height between the top of the threshold and the bottom of the stop. This means that a 36-inch by 80-inch door is required when using standard-size doors.

3. Provide a landing on the interior and exterior sides of the door. Build each landing at least as wide as the door. Example: if the door is 36 inches wide, then build each landing at least 36 inches wide. Build each landing at least 36 inches deep, measured in the direction of travel.

4. Build the interior and exterior landings not more than 11/2 inches below the top of the threshold.

5. You may build the exterior landing not more than 73/4 inches below the top of the threshold, if the egress door does not swing over the landing. You may build the exterior landing with not more than a 2 percent slope away from the door. You may have a storm door or a screen door swing over any landing.

6. Provide a ramp or a stairway to any egress door that is not at grade level.

Exterior Doors

2. Build each landing at least as wide as the door served. Example: if the door is 36 inches wide, then build each landing at least 36 inches wide.

3. Build each landing at least 36 inches deep, measured in the direction of travel.

4. Build each landing not more than 11/2 inches below the top of the threshold.

5. You may build the exterior landing with not more
than a 2 percent slope away from the door.

6. You are not required to build a landing on the exterior side of a door if: (a) a stairway of not more than two risers is on the exterior side and (b) the exterior door does not swing over the stairway.

7. You may build an exterior landing not more than 73/4 inches below the top of the door threshold if the exterior door does not swing over the landing.

8. Provide a ramp or a stairway to any exterior door that is not at grade level.

9. You may have a storm door or a screen door swing over any stairway and landing serving as a door into the house.

10. You are not required to build a landing on the exterior side of a door that opens to a narrow, above-grade balcony or similar structure.

Door & Window Hazards

You may have seen pictures of people severely cut when they fell or were pushed through doors and windows containing regular glass. Regular glass usually breaks into large pieces that can cause severe injury. Safety glass shatters into very small pieces that are less likely to cause severe cuts.

General codes designate several locations as hazardous, where people could fall or be pushed through glass. These locations are mostly near doors, near water, and near stairs. A large window where the sill is close to the floor is also a hazardous location.

Safety glazing usually means tempered glass; however, other materials also qualify. This is why it is called safety glazing, not safety glass. Most safety glazing should be identified with permanent writing in one corner of the glazing. This writing can be very difficult to see, so look closely before deciding that glazing is not safety glazing.

Another window hazard involves children falling from windows where the sill is close to the floor. Recent general codes require a mechanism that prevents a child from opening these windows enough so that they can climb through them and fall.

Safety glazing and fall hazard rules are complicated and have many exceptions. Our objective here is to introduce the subject and point out some hazardous locations that you might encounter if you remodel or add to your home.

2. Use safety glazing in windows that are within 24 inches on either side of a door. Exceptions include decorative glazing and windows when the bottom edge of the glazing is located 60 inches or more above the walking surface.

2. Use safety glazing in stairway handrail guards.

3. Use safety glazing in windows within stairways when the bottom edge of the glazing is less than 36 inches above the adjacent walking surface. Exceptions include if a handrail is between the stairs and the window and if the window is 36 inches or more away from the nearest part of the stairs.

4. Use safety glazing in windows within 60 inches of the last tread at the bottom of a stairway when the bottom of the glazing is less than 36 inches above the adjacent walking surface.

2. Use safety glazing in walls, enclosures, and fences that are less than 60 inches horizontally from the edge of bathtubs, showers, swimming pools, whirlpool tubs, hot tubs, saunas, and steam rooms. Exceptions include windows when the bottom edge of the glazing is located 60 inches or more above the walking surface and windows that do not face the bathtub, etc.

2. You may comply with this provision by permanently restricting the window opening distance, except where the window serves as an emergency escape and rescue opening.

3. You may comply with this provision by installing a window opening control device that complies with ASTM F2090.

Ventilation & Exhaust

Controlling moisture levels in a home is important for your comfort and health, as well as for the health of your home. Although inadequate moisture levels can cause discomfort for some people and can cause furnishings and some construction materials to become brittle, it is not usually a significant risk to you or to your home, so the IRC has no provisions governing minimum moisture and humidity levels. Too much moisture, however, can be a significant risk to you and your home, so the IRC has several provisions governing the removal of excess moisture. Current indoor air quality best practices also encourage removal of excess moisture and other contaminants from the home.

The greatest threat posed by water vapor is that it provides one of the three things that mold needs to grow. The other two are the correct temperature and food. Mold grows at the same temperatures we humans prefer, so there is little we can do about that. Because mold eats almost any wood-based product and our homes are filled with these products, there is little we can do about the food risk. The one thing we can do something about is moisture.

Water vapor travels in the air. When water vapor condenses on visible surfaces, it provides the moisture that mold needs. We then see what is often called mildew. Mildew is another name for mold. When water vapor travels into attics and wall cavities, it can condense and provide moisture for mold. Mold can grow in these hidden spaces for long periods before it is discovered. Damage to your home and health can be significant when mold grows for long periods of time.

Water vapor is always present in every home. Some water vapor occurs naturally in the air. We introduce some water vapor into the home with every breath we take. Much of the water vapor in a home results from activities such as bathing, cooking, and clothes drying. The IRC has provisions that help remove the excess water vapor caused by these activities.

2. You may replace the glazing with artificial light and exhaust ventilation. Provide exhaust ventilation of at least 20 cubic feet per minute (cfm) continuous ventilation or at least 50 cfm for a switched ventilation fan.

3. Comply with the ventilation fan manufacturer’s instructions or general codes about exhaust duct type and length. Three-inch diameter duct may not be allowed as an exhaust duct. Four-inch diameter or larger duct may be required.

4. Discharge bathroom and toilet room ventilation fan exhaust directly outdoors. Discharging a ventilation fan exhaust duct into or toward an attic, soffit, or crawl space ventilation opening does not comply with this provision.

5. Terminate exhaust fans at least: (a) 3 feet from property lines, gravity air intake openings, operable windows and doors; (b) 10 feet horizontally or 3 feet above mechanical air intake openings (such as for a heat recovery ventilation unit).

6. Do not recirculate air from bathrooms within a residence or into another residence.

7. Provide an automatic or gravity-operated damper for exhaust systems that will close the damper when the system is not operating.

8. Do not direct outdoor exhaust openings, such as from bathroom and kitchen exhaust fans, onto a walkway.

9. Protect outdoor air intake and exhaust openings with a corrosion-resistant screen having openings at least 1/4 and not more than 1/2 inch or by louvers, dampers, or similar means. This does not include clothes dryer exhaust openings. Do not cover clothes dryer exhaust openings with a screen.

10. Protect outdoor openings against local weather conditions, such as rain and snow infiltration and blockage by snow accumulation.

2. Terminate a kitchen exhaust hood duct, if any, to the outdoors when natural or mechanical ventilation is not provided in the kitchen area. Natural ventilation usually means an operable window in the kitchen area. Mechanical ventilation may be provided by a ducted central heating system that is connected to a ventilation opening terminating outdoors. Mechanical ventilation may be provided by a heat recovery or energy recovery ventilation system. Most homes have either natural or mechanical ventilation in the kitchen area, so external discharge of range hoods is rarely required.

3. You may, but are not required to, install a recirculating kitchen hood if the kitchen is provided with natural or mechanical ventilation.

4. Provide a backdraft damper at the duct termination or other approved location. Many kitchen hoods and cabinet-mounted microwave ovens have backdraft dampers integrated into the appliances.

2. Use galvanized steel, stainless steel, or copper to construct kitchen exhaust ducts.

3. Seal the exhaust duct air tight to avoid leaking flammable grease into wall or floor cavities or between the kitchen exhaust hood and the kitchen cabinet.

2. Provide a backdraft damper at the duct termination or other approved location. Many kitchen exhaust hoods and cabinet-mounted microwave ovens have backdraft dampers integrated into the equipment.

2. Provide makeup air for exhaust fans with a capacity of more than 400 cfm. Install a gravity operated or an electrically operated damper to open and close the takeup air duct.

1. Leave enough space between the microwave and the range top. A typical instruction is to have at least 66 inches between the floor and the top of the microwave, at least 30 inches between the range top and the bottom of the cabinet, and at least 2 inches between the bottom of the microwave and the range control panel.

2. Connect the microwave to a dedicated 120-volt circuit. Most microwaves should be served by a 20-amp circuit.

3. Plug a microwave that comes with an attachment plug into a receptacle. Do not connect the microwave directly to the electrical wires, and do not use an extension cord.

4. Use the size and type of exhaust duct material and termination fittings specified by the microwave manufacturer. Do not exceed the exhaust duct effective length specified by the manufacturer. Effective length adds for the losses created by elbows and termination fittings.

5. Connect the microwave to the exhaust duct. Do not simply blow the exhaust at the hole in the cabinet where the exhaust duct is located.

6. Install the backdraft damper if one is supplied with the microwave.

2. Do not connect clothes dryer exhaust ducts to any other system, such as bathroom exhaust fan ducts, plumbing vents, or fuel-burning equipment vents and flues.

3. Do not install clothes dryer exhaust ducts in or through any fireblocking-, draftstopping-, or fire-resistance-rated assembly, unless the duct is constructed and installed to maintain the code that requires fireblocking or draftstopping.

4. Do not run clothes dryer exhaust ducts into or through other ducts or plenums. Example: do not run a clothes dryer exhaust duct into or through an HVAC supply or return duct or into or through a combustion air duct.

5. Install the clothes dryer exhaust duct during construction if space for a clothes dryer is provided.

6. You may install a dryer duct booster fan to extend the dryer exhaust duct’s length. Install the fan according to the fan manufacturer’s instruction.

2. Install duct joints so that the inside part of the joint fits into the outside part of the joint in the direction of the air flow.

3. Fasten duct joints with mechanical fasteners, such as screws or pop rivets. Do not use screws or other fasteners that penetrate the duct more than 1/8 inch. Longer fasteners could trap lint.

4. Seal the duct joints with metal tape or mastic.

5. Support the duct at least every 12 feet. Joints and elbows are vulnerable areas for separation.

6. Protect the duct with at least 16-gauge shield plates if the duct is within 11/4 inches from the edge of a framing member. Extend the shield plate at least 2 inches above sole plates and below top plates. Protect the duct with shield plates at any other location where it is likely to be penetrated by fasteners.

2. Add 21/2 feet for every 45-degree bend and 5 feet for every 90-degree bend to the dryer duct’s developed length. You may use the manufacturer-provided developed length for smooth radius bends. You may use the IRC table for smooth radius bend developed length if the manufacturer’s instructions are not available.

3. Do not include the transition duct in the dryer duct developed length.

4. Locate a permanent label within 6 feet of the clothes dryer exhaust duct connection that shows the exhaust duct’s developed length. This requirement applies only when the duct developed length is more than 35 feet.

2. Locate the clothes dryer exhaust duct termination at least 3 feet from: (a) the property line and (b) operable and non-operable openings. Operable openings include windows and doors. Non-operable openings include eave ventilation openings and combustion air openings. This provision does not apply if the clothes dryer manufacturer’s installation instructions allow other locations. The clothes dryer manufacturer is rarely known during construction, so the manufacturer’s installation instruction exception rarely applies.

3. Provide a backdraft damper at the duct termination or at another approved location.

4. Do not install a screen at the exhaust duct termination. A screen will trap lint.

5. Make the open area of the exhaust duct termination at least 12.5 square inches.

2. Limit the transition duct length to 8 feet.

3. Use only one piece of transition duct. Do not splice together two or more lengths of transition duct material.

4. Do not run the transition duct through walls or in concealed spaces.

2. Provide a net free opening of at least 100 square inches when clothes dryers are installed in closets or provide makeup air by other approved means.

Smoke & Carbon Monoxide Alarms

Smoke alarms and carbon monoxide (CO) alarms have been required in houses for many years. Combination smoke and CO alarms are not preferred, because the service life of the different alarms are different, meaning that one alarm could fail before the other.

You should replace old smoke and carbon monoxide alarms. Smoke alarms have a useful life of about 10 years. Carbon monoxide alarms have a useful life of about 7 years. Install carbon monoxide alarms near all bedrooms and inside bedrooms with a fuel-burning appliance, such as a gas fireplace.

2. Do not install an ionization smoke alarm closer than 20 feet horizontally from a permanently installed cooking appliance. Do not install a photoelectric smoke alarm closer than 6 feet horizontally from a permanently installed cooking appliance.

3. You may substitute a security system that includes smoke alarms if it provides the same protection as hard-wired smoke alarms. The security system smoke alarms must: (a) comply with the National Fire Protection Association (NFPA) 72 standard and (b) must be a permanent fixture in the home. Security system smoke alarms installed as a substitute system cannot be leased. They must be a permanent part of the home.

4. You are not required to locate smoke alarms: (a) in crawl spaces and in uninhabitable attics, and (b) on the middle level of split-level homes if smoke alarms are installed on the upper level, if the middle level is less than one story below upper level, and if there is no door between levels. Note that some jurisdictions require smoke alarms on all levels of a split-level home.

2. Connect all smoke alarms together so one alarm activates all alarms (interconnection). Physical interconnection is not required if the alarms are listed for wireless interconnection.

3. Provide arc-fault circuit-interrupter protection for the smoke alarm primary power.

2. Install an alarm outside of bedroom areas in the immediate vicinity (usually about 10 feet) of all bedrooms.

3. Connect all carbon monoxide alarms together so one alarm activates all alarms (interconnection). Physical interconnection is not required if the alarms are listed for wireless interconnection.

4. Install carbon monoxide alarms in a bedroom if a fuel-fired appliance is located in the bedroom or in an attached bathroom.

Structural Components

A safe and healthy building begins with a solidly built structure. The building’s foundation should rest on stable soil and should be strong enough to support the home during normal conditions as well as during disasters, such as hurricanes and earthquakes. The building’s floors, walls, and roof should be secured to the foundation and to each other and should be strong enough to support the home during extreme conditions.

This chapter will help you understand basic structural requirements for building as defined by the building codes. The intent is to help you identify work that may violate building codes so that you can bring it to the attention of a contractor or other qualified professional. Except for projects such as simple decks and storage sheds, you should seek guidance from qualified professionals before using the information in this chapter to design you own buildings or to perform structural remodeling on existing buildings.

• Decks

• Floor Systems

• Wall Systems

• Wall Penetration Flashing

• Roof Systems

2. Verify the seismic design category with the local building official. The following may be in seismic design areas: large parts of Alaska, California, Hawaii, Nevada, Oregon, and Washington State; small parts of Arizona, Colorado, Idaho, Montana, New Mexico, New York, and Utah; the area near Memphis, Tennessee, and the area near Charleston, South Carolina.

2. Verify the wind design category with the local building official. The following may be in high wind design areas: much of Florida and Hawaii; the areas within about 100 miles of the coastlines of Alabama, Alaska, Georgia, Louisiana, Mississippi, North and South Carolina, Texas, and Virginia; the areas within about 50 miles of the coastlines of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, and New York. Several “Special Wind Areas” exist in scattered areas of the country. These areas are mostly in mountainous areas and in the West.

A load is a force (weight) placed on a component of a building. Example: a building’s foundation carries the load of the entire building. The dead load is the weight of the construction materials, such as drywall, shingles, siding, and floor coverings, and the weight of fixed equipment, such as a water heater. The live load is the weight of people and furnishings that occupy a building. A point load is a load in a small area. The heel of a high-heel shoe is an example of a point load. Environmental loads include wind, snow, and forces created during earthquakes.

Foundations

2. Have a geotechnical engineer evaluate the soil in areas known to have expansive or other unfavorable soils or if the soil-bearing capacity is unknown. Beware of clay soils. Some clay soils are unstable and can cause serious foundation problems.

3. Use the following table to estimate soil-bearing capacity if the soil type is known and if the local building official approves.

2. Refer to general codes for special footing and footing reinforcement requirements in seismic design areas.

2. Project spread footings at least 2 inches beyond the foundation wall. Do not project the footing beyond the foundation wall more than the thickness of the footing. Example: if the footing is 6 inches thick, then the edge of the footing should be not more than 6 inches beyond the edge of the foundation wall.

3. Locate the bottom of footings at least 12 inches below finish grade or below the local frost line, whichever is deeper. This does not apply to accessory buildings with an area 600 square feet or less and an eave height of 10 feet or less, and this does not apply to decks not supported by the home.

4. Do not place footings on frozen ground unless the frozen condition is permanent (permafrost).

5. Make the top surface of footings level.

6. You may slope the bottom of footings not more than 10 percent, without reducing the minimum thickness.

7. Make step footing thickness at least 6 inches. Make step footing height not more than the length of the footing above the step.

2. Use air-entrained concrete (between 5 and 7 percent total air content) in severe weathering potential environments if the concrete may be subject to freezing and thawing during construction.

2. Use at least 3,000 psi air-entrained concrete (between 5 and 7 percent total air content) in moderate and severe weathering potential environments.

2. Use at least 3,000 psi air-entrained concrete (between 5 and 7 percent total air content) in moderate weathering potential environments.

3. Use at least 3,500 psi air-entrained concrete (between 5 and 7 percent total air content) in severe weathering potential environments.

4. You may use at least 4,000 psi air-entrained concrete with at least 3 percent total air content in steel-troweled garage floors in moderate and severe weathering potential environments.

2. Install and tighten a nut and washer on each bolt. Verify washer size with your local building official.

3. Locate the bolts at least seven bolt diameters and not more than 12 inches from the ends of each plate and not more than every 6 feet on center in between.

4. Locate bolts in the middle third of the plate.

5. Install at least two bolts per plate section.

6. Embed the bolts at least 7 inches into the foundation.

7. Use approved fasteners to anchor the sole plates of interior load-bearing walls that are not braced walls.

8. You may substitute anchor straps for bolts if they provide equal anchorage. Place straps in the same locations as bolts, or per strap manufacturer’s instructions.

9. Refer to general codes for foundation anchor exceptions involving braced walls 24 inches long and shorter. These walls may require 1 or 0 foundation anchors.

Crawlspaces

2. Install covers in the ventilation openings. Use screens, grates, grills, or plates with openings at least 1/8 inch and not more than 1/4 inch.

3. Subtract the space used by opening covers from the net free ventilation area of a ventilation opening. Example: a 1-square-foot opening may be reduced to an effective 2/3-square-foot opening when covered by a cast iron grill or grate. The cover manufacturer’s instructions should indicate the cover’s opening reduction amount.

4. Locate a ventilation opening not more than 3 feet from every corner of the crawlspace wall.

5. There is considerable controversy about the effectiveness of crawlspace ventilation, particularly in warm, humid climates. Check with a qualified energy efficiency professional before adding insulation between floor joists in crawlspaces. Check the condition of existing floor joist insulation in crawlspaces at least annually.

(a) Cover all exposed soil in the crawlspace floor with an approved vapor retarder, such as 6-mil, preferably thicker, polyethylene sheeting.

(b) Lap all vapor retarder seams by at least 6 inches, and seal or tape the seams.

(c) Extend the vapor retarder at least 6 inches up the crawlspace wall, and attach and seal the vapor retarder to the wall.

(d) Provide one of the following ventilation methods:

• continuous mechanical exhaust ventilation

• a conditioned air supply at a rate of 1 cfm for every 50 square feet of crawl space floor area and provide a return air opening to the building interior

• dehumidification designed to provide at least 70 pints of moisture removal per day for every 1,000 square feet of crawlspace floor area

2. Do not connect the return air opening for the building interior to a forced-air return duct. Use an opening in the floor or use an unpressurized duct between the crawl space and the building interior.

3. There is some controversy about providing conditioned air to a crawl space. Do not exceed the 1 cfm conditioned air ventilation rate.

Decks

Most decks are relatively simple structures, but even a basic deck project must conform to the requirements of building codes in your area. In fact, virtually every aspect of your deck—from its location on your property to the design you choose and the materials you buy to build it—must meet stringent guidelines for safety. Codes vary, sometimes significantly, among jurisdictions. Your local building inspector can provide you with a list of the relevant deck codes and help you interpret them so you can create code-compliant plans for your deck project. You may also want to download a free PDF copy of the “DCA6-12 Prescriptive Residential Deck Construction Guide” (see Resources).

2. Drill holes for bolts at least 1/32 inch and not more than 1/16 inch larger than the bolt. Predrill holes for 1/2-inch-diameter and larger lag screws.

3. Use hot-dipped zinc-coated galvanized steel or flexible flashing material when installing flashing at the deck ledger. Be sure that the flexible flashing is approved for exposure to sunlight. Do not use aluminum flashing.

4. Use at least #2 grade preservative-treated lumber or #2 grade naturally durable lumber for deck structural members. Lumber for deck structural components should be rated for ground contact, UC4A or better. You may use approved composite materials for components, such as deck flooring and railings. Read and follow manufacturer’s instructions when using composite materials.

5. Field-treat cuts, holes, and notches in preservative-treated wood with an approved preservative, such as copper napthenate.

6. Consult with the building inspector or a qualified engineer when building decks in seismic and high wind zones, in areas with heavy snowfall, and when building complex decks, such as multi-level decks.

2. Secure the deck ledger to one of the following band or rim joists: (a) 2-inch-thick (11/2-inch actual thickness) SPF sawn lumber, (b) 1 inch minimum thickness by 91/2 inches deep Douglas fir laminated veneer lumber, or (c) another approved engineered material.

3. Secure the band or rim joist to sawn lumber joists or wood I-joists that are perpendicular to the band or rim joist.

4. Use hold-down tension devices to provide lateral load connections. You may use one of the following methods.

(a) Install two 1,500 pound hold-down tension devices according to the device manufacturer’s instructions.

(b) Install four 750 pound hold-down tension devices according to the device manufacturer’s instructions.

5. Support the band or rim joist directly on the foundation or on a wall supported directly on the foundation. Do not support the band or rim joist using a cantilevered structure, such as a bay window or a framed chimney. Do not support the band or rim joist on veneer, such as masonry and stone.

6. You may use other methods and materials when the details are designed by a qualified structural engineer.

7. You may make a deck entirely self-supporting as an alternative to attaching the deck to the home.

2. Install at least 1/2-inch hot-dipped galvanized lag screws or machine bolts (not carriage bolts) as specified in Table 3B.

NOTE: there are proprietary screws that are thinner than 1/2 inch and are approved for attaching deck ledgers to the home. Read and follow the manufacturer’s instructions if you use these screws.

3. Install a washer on each end of the machine bolts and a washer on the head end of the lag screws.

4. Make the distance between the interior face of the ledger board and the exterior face of the band board (rim joist) not more than 1 inch.

5. Use lag screws that are long enough to penetrate the band or rim board but not long enough to penetrate through the interior wall.

2. Place the bottom of footings for deck support posts that are within 5 feet from the house at the same level as the house footings.

3. Refer to DCA-6 or local codes for footing size and thickness.

4. Space footings as required for beam support. See the DECK BEAMS section shown here.

2. Fasten joist hangers using the size and type of fastener specified by the joist hanger manufacturer. In general, place a fastener in every round and oblong hole.

3. Support joists on a joist hanger (the joist should be fully seated in the hanger), on at least 11/2 inches of wood, or on at least 3 inches of concrete or masonry.

4. You may use three 8d nails to fasten joists that bear on top of a beam to the beam if the deck is supported by the house. Best practice is to use hurricane clips to fasten all joists to a beam.

5. Secure the rim joist to the deck floor joists using at least three 10d nails or three #10 × 3-inch wood screws.

6. Use Table 3C or local codes to determine the correct joist span and on center spacing.

2. Place splices between beam members above deck posts.

3. Use Table 3D or local codes to determine the correct beam span and on-center post spacing.

2. Consult with the building official or an engineer about wood deck support posts taller than 14 feet and about support posts that are not preservative-treated wood, such as steel posts.

3. Secure the post to the footing. You may embed the post in the footing; however, this is not recommended because the post may deteriorate over time. Best practice is to use a post base.

4. Secure the post to the beam as described in the photo caption (right).

2. Do not install 2-inch-thick flooring across joists that are more than 24 inches on center when the flooring is perpendicular to the joist or more than 16 inches on center when the flooring is diagonal (maximum 45 degrees) to the joist.

3. Do not install 11/4-inch-thick flooring across joists that are more than 16 inches on center when the flooring is perpendicular to the joist or more than 12 inches on center when the flooring is diagonal (maximum 45 degrees) to the joist.

4. Install two 8d threaded nails or two #8 × 3-inch wood screws per floorboard in each joist.

5. Install flooring across at least 4 joists.

6. Leave about 1/8 inch between flooring boards, including at the ends, to allow for drainage and for expansion.

7. Install other listed deck flooring material according to manufacturer’s instructions.

2. Leave at least 5 inches of uncut wood when cutting the stair risers and treads into the stringers. Do not cut the stringer past the riser and tread.

3. Do not exceed 6 feet of unsupported length for deck stair stringers where the risers and treads are cut into the stringer (cut stringers).

4. Do not exceed 13 feet, 3 inches of unsupported length for deck stair stringers where the risers and treads are not cut into the stringer (solid stringers).

5. Measure stringer length horizontally. You may support long stringers near the center to reduce the unsupported length.

6. Provide a solid landing, such as concrete, at the bottom of deck stairs. Support the stringers on the landing or by appropriate footings.

7. Support the entire stringer plumb cut at the top landing on the deck rim board or by other approved means.

8. Attach the stringers to the top landing support using hangers or brackets. Do not rely only on nails or screws to attach stringers to supports.

9. Do not exceed 18 inches of unsupported length for deck stair treads using 2 × 4 or 5/4 Southern Pine. Refer to DCA-6 for maximum stair tread lengths for other lumber sizes and species. Install treads made from composite materials according to manufacturer’s instructions.

2. Space deck guard 4 × 4 support posts at least every 6 feet. This also applies to stair guards and handrails.

3. Secure the deck guard support posts to deck floor joists using at least 1/2-inch-diameter bolts and attachment hardware. Do not rely only on the deck band and rim boards to secure deck guard support posts.

4. Refer to DCA-6 or attachment hardware manufacturer’s instructions for information about attaching deck guard support posts if the posts do not line up with deck floor joists.

2. Install bracing between the deck support posts and a deck rim board, floor joist, or blocking on free-standing decks that are more than 2 feet aboveground.

3. Use 2 × 4 or larger lumber for the brace.

4. Secure the braces using at least 3/8-inch-diameter bolts with washers on both ends.

5. Secure the brace at least 2 feet away from the support post.

Floor Systems

2. Use 40 psf live load and 10 psf dead load for joists under living areas, other than bedrooms, and under decks, and balconies, in most cases.

3. Use L/360 deflection (length of joist span in inches divided by 360) for all floor joists.

4. Refer to the IRC or to the AF&PA Span Tables for Joists and Rafters to find joist spans not contained in the following tables.

5. Apply the following tables to floor systems framed with nominal 2-inch-wide dimensional lumber, such as 2 × 10. An engineer must design floor truss and I-Joist systems.

2. You may separate the additional joists under a load-bearing wall, if necessary, to fit pipes, vents, or ducts. Install solid 2-inch-thick blocking at least every 4 feet along the full depth of the separated joists.

3. Place load-bearing walls that run perpendicular to the floor joists not more than one joist depth from the supporting wall or beam below unless the joists are sized to carry the load. Perpendicular joists run at a 90-degree angle to the wall being supported. Example: place a load-bearing wall that runs perpendicular to 2 × 10 floor joists not more than 10 inches from the supporting wall or beam below.

2. Place at least 3 inches of a floor joist, header, girder, or beam on the supporting masonry or concrete wall. Comply with this requirement when the member bears directly on the masonry or concrete wall, not on a sill plate that bears on the wall. This requirement usually applies to beams and girders.

3. You may support floor joists on at least a 1 × 4 ledger if the ledger is attached to each stud and if the joist is attached to a stud.

2. Install blocking at all intermediate load-bearing supports in seismic design areas.

2. You may use solid, full-depth blocking, wood or metal diagonal bridging, or other means to provide required floor joist bridging. Some code officials require bridging on all floor joists regardless of what the code stipulates.

2. You may use a single header joist if the header joist span is not more than 4 feet wide.

3. Install approved joist hangers or a 2 × 2 ledger strip to connect tail joists to header joists and header joists to trimmer joists.

2. Install approved joist hangers to connect header joists to trimmer joists if the header joist span is more than 6 feet wide.

3. Install approved joist hangers or a 2 × 2 ledger strip to connect tail joists to header joists if the tail joists are more than 12 feet long.

2. Support wood floor sheathing panel edges with solid blocking, tongue-and-groove edges, or other approved means. An additional underlayment layer that is at least 1/4 inch or 3/4-inch wood floor covering can substitute for edge support in some cases.

3. You may use wood floor sheathing panels (such as 23/32-inch and 3/4-inch nominal thickness plywood or OSB and 3/4-inch sanded plywood) as a combination subfloor and underlayment. Install combination subflooring as described in #1 above. Be aware that while combination subflooring panels comply with the IRC, they may not comply with manufacturer’s installation for some floor coverings, such as tile.

2. Use at least 1/2-inch drywall, 3/8-inch wood structural panels (plywood or OSB), or other approved material.

3. Divide the space to be draftstopped into areas that are approximately equal.

4. Install the draftstopping material parallel with the framing.

5. Repair draftstopping that is damaged or penetrated by pipes, ducts, or other materials.

A notch is a piece cut from the smaller dimension of framing lumber, such as a stud or joist. Use the actual dimensions to determine the depth of framing lumber and when calculating the maximum notch depth. Actual dimensions are the dimensions of framing lumber after finishing at the mill. Example: the nominal dimensions of a 2 × 6 are 2 inches by 6 inches, and the actual dimensions, after finishing, are about 11/2 inches by 51/2 inches.

2. You may notch solid lumber rafters, floor and ceiling joists, and beams not longer than one-third the depth of the member. Example: notch the top or bottom of a 2 × 10 joist not longer than 31/16 inches.

3. You may notch solid lumber rafters, floor and ceiling joists, and beams only within the outer one-third of the span. Example: notch a 10-foot-long joist only within 40 inches from each end.

4. You may notch the tension side (bottom) of solid lumber rafters, floor and ceiling joists, and beams more than 4 inches thick only at the ends.

5. You may drill holes in solid lumber rafters, floor and ceiling joists, and beams with a diameter not more than 1/3 of the depth of the member. Example: drill a hole with a diameter not more than 31/8 inches in a 2 × 10 joist.

6. Locate holes at least 2 inches from the edge of the member and at least 2 inches from any other hole or notch.

7. Use actual joist depths, not nominal joist depths. Example: use 91/4 inches for a 2 × 10 joist, not the nominal depth of 10 inches.

Wall Systems

Whether they are interior or exterior, load-bearing or nonload-bearing, made from wood studs or metal, walls must meet very specific construction standards to ensure that they do not impede the structural integrity of a house and do their part to prevent fires from spreading within wall cavities. Nevertheless, be aware that designing and building load-bearing walls is a closely regulated process. In most cases, you would be well advised to consult a structural engineer to make sure that the lumber sizes and spacing conform to code standards and that any beams are appropriately sized, properly supported, and made from qualifying materials.

2. You may use utility grade wood for nonload-bearing walls.

3. Refer to general codes for more information about other wall height and stud spacing combinations.

4. Refer to general codes for wall height and stud spacing requirements in high wind, heavy snow load, and seismic design areas.

2. Offset joints where two pieces of top plate meet by at least 24 inches. You do not need to place a stud under a joint in a top plate unless the stud would be placed there for other reasons.

3. Lap one top plate from one wall over the top plate of an intersecting wall at the wall corners and at the intersection with load-bearing walls.

4. You may use a single top plate at the top of nonload-bearing walls.

5. Install one galvanized metal strap at least 0.054 inch thick (16 gauge) and 11/2 inches wide on a top plate if it is cut more than 50 percent of its actual depth. These metal straps are sometimes called FHA straps. It is not necessary to install a strap on both top plates for purposes of this section. You may need to install shield plate to protect plumbing pipes and electrical wires.

6. Extend the strap at least 6 inches beyond each side of the cut opening. Secure the strap with at least eight 16d nails on each side of the strap.

7. Apply this strap requirement to top plates in exterior and interior load-bearing walls.

8. You do not need to install the strap if wood structural panel sheathing covers the entire side of the wall with the notched or cut top plates.

9. Use at least one 2-inch-deep (nominal) bottom plate that is at least as wide as the studs. Note that some jurisdictions allow treated plywood to serve as the bottom plate for curved walls. Verify this local exception with the building official.

A notch is a piece cut from the smaller dimension of framing lumber, such as a stud or joist. Use the actual dimensions to determine the depth of framing lumber and when calculating the maximum notch depth. Actual dimensions are the dimensions of framing lumber after finishing at the mill. Example: the nominal dimensions of a 2 × 6 are 2 inches by 6 inches, and the actual dimensions, after finishing, are about 11/2 inches by 51/2 inches.

2. Notch a nonload-bearing stud not more than 40 percent of its actual depth. Example: notch a 2 × 6 nonload-bearing stud not more than 21/4 inches.

2. You may bore holes in load-bearing studs not more than 60 percent of their actual depth if you install a double stud and do not bore more than two successive studs.

3. Bore a hole in a nonload-bearing stud not more than 60 percent of its actual depth. Example: bore a 2 × 6 nonload-bearing stud not more than 31/4 inches in diameter.

4. Leave at least 5/8 inch of undisturbed wood between the hole and the stud edge.

5. Do not place a hole and a notch in the same horizontal section of the stud.

2. Frame cripple walls more than 4 feet tall as though they are full height walls. This means using the stud sizes and framing requirements previously described. Example: if full height wall studs on the same floor level as the cripple wall are 2 × 6, use 2 × 6 studs for the cripple wall.

3. Brace cripple walls using the same bracing method and length as the wall above, except multiply the cripple wall brace length by 1.15. Example: if the cripple wall is a 2-foot-tall basement wall and the wall brace length for the first story wall above is 3 feet, brace at least 3.45 feet (3 × 1.15) of the cripple wall.

4. Install sheathing that covers at least one full side of a cripple wall less than 14 inches tall. Fasten the sheathing to both the top and bottom plates.

5. Support cripple walls on a continuous foundation.

6. You may substitute solid blocking for a framed and sheathed cripple wall less than 14 inches tall.

7. Anchor cripple walls to the foundation like other framed walls.

8. Refer to the IRC for additional bracing requirements in seismic design areas.

Wall brace (braced wall panel). A wall brace is a full height wall with no vertical or horizontal offsets that has approved wall bracing material attached. A wood structural panel (such as OSB) and panel-type siding are common examples of approved wall bracing materials. Each braced wall must have an approved total length of wall braces. The total length of wall braces depends on: (a) the criteria described in the next section; (b) the type of bracing material, such as wood structural panels and panel siding bracing; (c) the story being braced; (d) the design wind speed; and (e) the seismic design category.

2. You may use a continuous sheathing wall bracing method. This means that all braced walls have sheathing, such as wood structural panels applied continuously to the walls, including above and below openings and on gable end walls. Refer to the IRC for requirements regarding panel lengths near openings and for panel installation and hold-down straps at the ends of continuously sheathed braced walls.

3. Refer to the IRC for information about other wall bracing materials and methods. Refer to manufacturer’s instructions for information about manufactured wall braces.

4. You may use different wall bracing methods within the same braced wall, and you may use different bracing methods on different stories. Example: you may use let-in bracing at one end of a braced wall and structural panel bracing on the other end. Use the highest required bracing length in the table when using different bracing methods in the same braced wall. Refer to the IRC for some restrictions when mixing wall bracing methods.

2. Begin the wall brace not more than 10 feet from the end of a braced wall.

3. Begin a wall brace not less than 20 feet from the closest edge of the next wall brace in the braced wall.

4. Do not exceed 60 feet between braced walls. Smaller distances between braced walls are required in the D series seismic design areas. Refer to the IRC.

2. Install at least two 48-inch-long wall braces in braced walls longer than 16 feet. Install at least one 48-inch-long wall brace or two smaller wall braces in braced walls 16 feet long or less. Install these braces even if Table 13A specifies a smaller length. Install the length of wall braces specified in Table 13A if the wall brace length in Table 13A is longer than 48 inches.

2. Fasten vertical joints at panel sheathing edges to studs. Fasten horizontal joints to at least (≥) 11/2-inch-thick blocking.

3. Use fasteners and uplift connectors as required by good engineering practices to connect rafters and trusses to wall braces and to connect the wall braces to framing in stories below.

4. Install at least (≥) 1/2-inch drywall on the interior side of wall braces. You will need to multiply the wall brace length by 1.40 if drywall is omitted. Space drywall fasteners not more than (≤) 8 inches on center at panel edges when using let-in wall braces.

2. Use wood structural panels that are at least 3/8 inch thick as the wall bracing material. Fasten 3/8-inch-thick wood structural panels using 6d common nails. Fasten 7/16-inch-thick wood structural panels using 8d common nails. Space the nails 6 inches on center at the edges and 12 inches on center at intermediate supports.

3. Build bracing units as full height walls with no openings and no vertical or horizontal offsets. A bracing unit must be one fully sheathed vertical wall segment.

4. Use bracing units that are at least 3 feet long when the walls are continuously sheathed with the wall bracing material. Continuously sheathed means all wall areas have structural sheathing applied, including above and below openings and at gable wall ends. Use bracing units that are at least 4 feet long when the walls are not continuously sheathed.

5. Begin a bracing unit not more than 12 feet from a wall corner. Make the distance between adjacent bracing units in the same wall not more than 20 feet. Place at least one bracing unit in any wall more than 8 feet long.

6. Determine the length of exterior walls as shown in the illustration shown here. Do not include open structures, such as porches, decks, and carports. Interior walls do not count as braced walls.

7. You may count bracing units that are wider than the minimum width as multiple bracing units. Divide the width of the bracing unit by the minimum bracing unit width to determine the number of bracing units. Example: a bracing unit is 7 feet wide. The wall is not continuously sheathed, so the minimum bracing unit width is 4 feet. The 7-foot-wide bracing unit counts as 13/4 bracing units (7/4 = 1.75).

8. Do not count sheathed wall segments that are narrower than the 3- or 4-foot minimum lengths as bracing units. Refer to the IRC for exceptions involving certain continuous sheathing methods at garage doors and large openings.

2. Install panels that are at least 48 inches wide and cover at least three stud bays for studs spaced 16 inches on center.

3. Secure 3/8-inch-thick wood structural panel bracing to studs using at least 6d common nails spaced not more than 6 inches on center at panel edges and 12 inches on center at intermediate supports. Secure 7/16-inch-thick panels (span rating 24/16) using 8d common nails spaced as previously described.

4. Install solid blocking where panel joints occur between studs to maintain fastener spacing. Use at least 11/2-inch-thick wood for blocking. The blocking is usually the same dimensions as the studs. Example: 2 × 6 blocking is normally used with 2 × 6 studs, although 2 × 4 blocking is acceptable.

5. You may use wood structural panel wall bracing on all stories and in all wind speed and seismic design areas.

Do not confuse fireblocking with draftstopping (see here). Draftstopping limits the horizontal movement of air in concealed floor/ceiling assemblies.

2. Install fireblocking in concealed wall spaces at every ceiling and floor level. An intact top and bottom plate usually provides fireblocking in platform framing.

3. Install fireblocking where concealed vertical and horizontal wall spaces intersect. Examples of concealed horizontal spaces include soffits for kitchen cabinets and recessed vanity lights, and drop ceilings.

4. Install fireblocking between stair stringers at the top and bottom of each flight of stairs. Also install drywall (at least 1/2 inch thick) on all walls and soffits if the area under the stairs is accessible by a door or access panel.

5. Install fireblocking around chimneys and flues where they intersect framing at floor and ceiling levels.

6. Install fireblocking in concealed wall spaces if the concealed space is open for more than 10 feet horizontally. A common example of a long concealed horizontal wall space is a double wall built using two rows of staggered studs. Another example is a large arched opening between rooms.

2. Install backing at any joints in fireblocking material when using wood structural panels or particleboard. Use the same fireblocking material for the backing. Example: if a joint exists in OSB fireblocking material, place another piece of the same OSB material over the joint. Most general codes do not state how far to extend the backing.

3. Do not use loose fill insulation as a fireblocking material unless it is specifically tested and approved for the intended location and installation method.

4. Repair fireblocking that is damaged or penetrated by pipes, ducts, or other materials.

Wall Penetration Flashing

It is not possible to overstate the importance of flashing to the long-term integrity and health of your home. Sealants, such as caulk, degrade over time and require maintenance. Exterior wall coverings move and crack, creating gaps into which moisture can flow. People often do not maintain caulking and sealants as they should. The best long-term solution to avoiding moisture intrusion is a combination of a water-resistant barrier and flashing integrated to form a drainage plane that prevents moisture from reaching vulnerable wood framing materials and drains the moisture away from the structure.

2. Use flashing, fasteners, and other materials that are compatible with each other and with surrounding materials. Incompatible materials will react with each other and degrade over time. Example: do not use galvanized material with aluminum or with copper.

3. Flash and seal all wall penetrations and other vulnerable areas so that moisture will not enter the structure. Flash and seal any point where moisture could enter the structure, regardless of whether it is mentioned in the list of areas where flashing is specifically required.

4. Install flashing “shingle fashion” so that upper flashing laps over lower flashing, resulting in a drainage plane that will drain water toward a designated discharge point. This includes integrating flashing with the water-resistant barrier.

5. Extend flashing to the surface of the exterior wall finish material if necessary to assure that water is drained. This may be necessary with brick veneer, at horizontal joints in panel siding, with Z flashing at window and door headers, and at other drainage points.

2. Install pan flashing at the window and door sills unless the window or door manufacturer’s instructions state otherwise. Integrate the pan flashing with jamb (side) flashing, header (top), and the weather-resistant barrier. Install all window and door flashing so that water drains away from the opening and out from the structure.

3. Install sidewall flashing where chimneys or other masonry construction intersect with walls.

4. Install projecting lips (sometimes called kick-out flashing) at chimneys and other sidewalls where a roof extends past a vertical sidewall. Kick-out flashing helps divert water away from this vulnerable intersection.

5. Install header/sidewall flashing under and at the ends of all copings and sills, including masonry, metal, and wood.

6. Install header/sidewall flashing above all wood trim that projects from the adjoining wall and forms a shelf where water can collect.

7. Install flashing at the attachment point of exterior porches, decks, balconies, stairs, or floor assemblies to wood-framed construction.

8. Install sidewall flashing at all roof and wall intersections.

How to Flash a Window & a Door

Roof Systems

This section addresses the roof structural system. Refer to other sections of this book, general codes, and manufacturer’s instructions for information about installing roof coverings. The number and size of the rafters or trusses is a vital element of home design, as are the methods for fastening these elements to the house structure. If you live in a coastal area or any region that is prone to earthquakes or hurricanes, a separate set of codes exists for your roof system. Be sure to enforce its more rigorous standards when you build.

2. Install at least a 2-inch (nominal thickness) hip rafter and valley rafter at all hips and valleys, including valleys formed when one roof is framed on top of another, collar tie, or ridge strap.

3. Support hip and valley rafters at the ridge with a brace to a load-bearing wall, or design the hip and valley rafters to bear the load at the ridge.

4. Design and support ridge, hip, and valley rafters as beams when the roof pitch is less than 3/12.

5. Design and support the ridge as a beam and design the walls supporting the ridge board to bear the ridgeboard load when framing cathedral and vaulted ceilings without ceiling joists and rafter ties.

2. Install purlins that are at least the same depth as the rafters they support. Example: use a 2 × 6 purlin to support a 2 × 6 rafter.

3. Use at least one 2 × 4 brace to carry the purlin load to a load-bearing wall. The purlin brace length should not exceed 8 feet without additional bracing (usually an additional 2 × 4 nailed to the brace). Purlin braces should bear on a load-bearing wall and may not slope at less than a 45-degree angle from horizontal. Space the purlin braces not more than 4 feet apart.

2. Space collar ties not more than 4 feet on center.

3. Locate collar ties in the upper one-third of the attic space.

4. Connect collar ties and rafters as specified in Table 10 (see here).

2. Toenail rafters to the top plate as specified in Table 10 (see here).

3. Install plates with a bearing area of at least 48 square inches when the plate bears on concrete or masonry. This means that the plate should have at least 48 square inches of surface area in contact with the masonry or concrete.

2. Install lateral support at bearing points on rafters and ceiling joists deeper than 2 × 10 (five-to-one depth-to-thickness ratio).

2. Leave at least 31/2 inches of wood above the notch (bird mouth cut) where the rafter bears on the exterior wall, and do not cantilever the rafter past the wall more than 24 inches.

3. Do not taper a ceiling joist more than the actual depth of the ceiling joist divided by 4 if notching the ceiling joist where it bears on the wall. Example: do not cut more than 17/8 inch of a 2 × 8 ceiling joist where it bears on the wall.

2. Install a method to prevent rafter thrust from pushing on supporting walls. You may use ceiling joists, rafter ties, or kickers to comply with this requirement.

3. Connect one rafter to one ceiling joist when the ceiling joists are parallel to the rafters. Locate the ceiling joists in the lower third of the attic area, if possible. Facenail these ceiling joists to rafters using 16d common nails or 40d box nails. (See Table 14.)

4. Connect one rafter to one rafter tie and connect the rafter tie to the corresponding rafter on the other side of the roof when the ceiling joists are not parallel to the rafters. Locate the rafter ties in the bottom one-third of the rafter height, if possible. Facenail rafters ties to rafters using the quantity of 16d common nails or 40d box nails indicated in Table 14. Use 2 × 4 or larger lumber for rafter ties.

5. You may substitute 2 × 4 kickers for rafter ties if the ceiling joists are not parallel to the rafters. Fasten the kickers to the rafters and to the ceiling joists as if the kickers were ceiling joists or rafter ties.

6. Lap ceiling joists that meet over interior walls or beams at least 3 inches, and facenail using the same quantity and type of nails indicated in Table 14. Apply this requirement when the ceiling joists are designed to resist rafter lateral thrust. This requirement usually applies when the ceiling joists are attached to the rafters.

7. You may butt the ends of ceiling joists together over interior walls or beams. Fasten the ceiling joists as specified in Table 10 (see here) if the ceiling joists are not designed to resist rafter lateral thrust. This exception usually applies when the ceiling joists are not attached to the rafters.

(a) You may reduce the required quantity of nails by 25 percent if the nails are clinched (the pointed ends sticking out from the wood are bent over).

(b) You may use fewer fasteners if you support the ridge board on load-bearing walls or if you design and support the ridge as a beam.

(c) You may use a smaller roof span column if you install purlins to support the rafters. Example: if you install purlins at the center of rafters with a roof span of 24 feet, you may reduce the roof span by 50 percent and use the 12-foot roof span column.

(d) You may reduce the actual rafter slope by one-third if you substitute rafter ties for ceiling joists, Example: if the actual rafter slope is 9/12, use 6/12 as the adjusted rafter slope, but because there is no 6/12 slope row, use the nearest more conservative 5/12 row.

(e) Increase the quantity of nails in the table if the ceiling joists or rafter ties are not located at the bottom of the attic space.

2. Refer to the IRC or engineered plans for wall attachment requirements when the limitations in #1 above do not apply. Some building inspectors require hurricane ties on all trusses and rafters.

2. All rafter spans in the tables below use L/180 deflection.

2. Refer to the IRC or to the AF&PA Span Tables for Joists and Rafters to determine spans for lumber widths, species, grades, and snow load factors not in these tables.

3. These tables apply to roof systems framed using standard 2-inch (nominal thickness) dimensional lumber. An engineer must design roof truss systems.

2. Install trusses so that a bow in either the top or bottom chord is not more than L/200 or 2 inches, whichever is less. L is the length of the truss chord in inches.

3. Install trusses that are out-of-plumb (vertical) by not more than D/50 or 2 inches, whichever is less. D is the depth of the truss in inches at the point of measurement.

4. Install trusses at load-bearing points not more than 1/4 inch from the location on the plans.

5. Install trusses that use the top chord as the weight-bearing point with a gap of not more than 1/2 inch between the inside of the load-bearing support and the first diagonal or vertical truss web.

2. Do not use trusses to carry the weight of equipment (such as furnaces or water heaters), use the attic area for storage, or hang storage units from trusses unless the trusses have been designed to carry the additional weight.

3. Do not repair damaged trusses without written instructions from a qualified engineer.

2. Provide a rough opening (size before finishing) for a ceiling attic access of at least 22 inches by 30 inches. Locate the opening in a hallway or other readily accessible location. Locate the opening so that at least 30 inches of unobstructed headroom exists at some point above the opening.

3. Provide a rough opening (size before finishing) for a wall attic access of at least 22 inches wide by 30 inches high.

4. You do not need to provide attic access if the ceiling and roof systems are built using non-combustible materials. This is rare in residential construction.

5. Refer to the IRC for additional access requirements if appliances are located in the attic.

2. You may reduce the 3-inch clearance requirement if the device is listed for a lesser clearance and is installed according to manufacturer’s instructions.

3. Install an insulation shield around any gas or oil vent that passes through an attic or other insulated area (such as a floor/ceiling assembly).

4. Use at least 26-gauge sheet metal for the insulation shield.

5. Extend the shield at least 2 inches above attic insulation material.

6. Secure the insulation shield to prevent movement of the shield.

Exterior Components

The primary function of the exterior components of a building is to keep the elements out. Of these elements, the most destructive is water. Water causes more damage than almost any other natural source, including fire and termites. Water can destroy most building materials, and it is an essential ingredient for mold growth.

In this chapter you will learn about three common water control issues. Shingle roof coverings are the most common type of material for keeping water that falls on the roof out of the home. You will learn about the code requirements for shingle installation and about where to install flashing that keeps water away from vulnerable areas, such as where roofs intersect with walls and chimneys. You will also learn about code requirements for water control around your home so that water stays out of basements and crawl spaces.

This chapter also contains information about fireplaces and chimneys. Water infiltration is common around these components, and fire safety is an additional important consideration.

• Fireplaces & Chimneys

Shingle Roof-Covering Installation

When it comes to installing roof coverings, it can be a little hard to define where enforceable codes end and ordinary best practices begin. But it is safe to say that most codes contain guidelines for installing roof coverings that, if followed, will ensure a long-lasting roof that keeps moisture from penetrating your house. The following information applies to asphalt shingles. It does not include asphalt-based roll roofing. This section applies to shingle roof-covering installation in almost all areas. Consult your local building inspector for additional requirements if you live in a very high wind speed design area, such as near the ocean.

Always read and follow the shingle manufacturer’s instructions. They are printed on every package of shingles. Details that seem minor, such as failing to install the starter course or incorrectly installing nails, can make a big difference in how the shingles perform under stress. Failing to follow instructions can void the shingle warranty. This section applies to shingle roof-covering installation in almost all areas. Consult your local building inspector for additional requirements if you live in a very high wind speed design area, such as near the ocean.

2. Install a double underlayment layer under shingles on roofs with a slope between 2/12 and 4/12.

3. Verify shingle manufacturer’s instructions about minimum roof slope. Some do not allow installation on slopes less than 21/2/12.

2. Lap horizontal joints at least 2 inches with the upper strip over the lower strip.

3. Lap end joints as specified by the shingle manufacturer. End joint laps are usually between 4 and 6 inches.

4. Offset end joints by at least 6 feet.

5. Use sufficient fasteners to hold underlayment in place. The IRC does not specify fastener type and quantity.

6. Minimize wrinkles and distortions in the underlayment. Wrinkles should not interfere with the ability of the shingle’s sealing strips to seal. Underlayment wrinkles and distortions can appear through the shingles, creating a cosmetic issue.

2. Use drip edge flashing that extends at least 1/4 inch below the roof sheathing and extends at least 2 inches up the roof deck.

3. Lap adjacent drip edge pieces at least 2 inches.

4. Attach drip edge using roofing nails spaced not more than 12 inches on center.

5. Install underlayment under the drip edge at rakes.

6. Install underlayment over the drip edge at eaves.

2. Begin again at the eaves and apply at least a 36-inch-wide strip of underlayment.

3. Lap each successive layer at least 19 inches over the previous layer, with the upper layer lapping over the lower layer.

4. Lap end joints at least 6 inches.

5. Use sufficient fasteners to hold underlayment in place. Most codes do not specify fastener type and quantity.

6. Install drip edge as previously described.

2. Install either a sheet of self-adhering, polymer-modified bitumen roofing or at least two layers of roofing felt bonded together with roofing cement. Begin the ice dam underlayment at the lowest edge of all roof surfaces, and extend it at least 24 inches beyond the exterior wall of the building.

3. Measure distances horizontally, not up the roof sheathing. Begin the 24-inch measurement from the interior side of the wall. Example: if the eaves extend 12 inches horizontally from the exterior wall of the building, extend the ice dam underlayment at least 39 inches horizontally from the edge of the eaves (assuming a 2 × 4 wall).

2. Place nails at least 6 inches away from the valley centerline, unless other spacing is approved by the shingle manufacturer.

3. Apply the shingles across one side of the valley at least 12 inches, or as recommended by the shingle manufacturer.

4. Apply shingles from the other direction to before the valley centerline, and trim the edges as recommended by the shingle manufacturer. Seal the cut shingles in a closed-cut valley, as recommend by the manufacturer. Sealing the cut shingles is frequently omitted.

2. Flash the cricket at the chimney wall using step and counter flashing that is compatible with the roof covering material.

3. Install the cricket with a vertical height at the chimney based on Table 23. W is the width of the chimney. Leave at least a 1-inch air space between a wood-framed cricket and a masonry chimney wall.

2. Flash the intersection of a sloped roof and a chimney according to the shingle manufacturer’s instructions. This typically includes step flashing covered with counter flashing.

3. Flash other roof penetrations, such as plumbing and gas vents, according to the shingle manufacturer’s instructions.

4. Flash skylights according to the skylight manufacturer’s instructions.

2. Use corrosion-resistant roofing nails (usually galvanized steel) with at least a 12-gauge shank and a 3/8-inch-diameter head. Use nails long enough to penetrate into the roof sheathing at least 3/4 inch and completely through any sheathing that is less than 3/4 inch thick. Install at least four nails per shingle strip, with a nail at 1 inch from each end and two nails equally spaced in the center of the strip.

Fireplaces & Chimneys

Installing a factory-built or gas fireplace is a do-it-yourself project because you can design and build the fireplace frame to suit your needs and add your own finish treatments. It all starts with some careful planning. Once you decide on the fireplace model and determine where to place it, order all of the vent pipes and fittings needed to complete the vent run.

NOTE: Consult the manufacturer’s instructions for the specifications regarding placement, clearances, and venting methods for your fireplace.

Start your planning by determining the best location for the fireplace. Placing the unit next to an exterior wall simplifies the venting required. One important specification for a direct-vented gas fireplace located in a basement is that the termination cap (on the outside end of the vent) must be 12 inches above the ground and away from openings, such as windows and doors.

For help with any of these planning issues, talk with knowledgeable dealers in your area. They can help you choose the best fireplace model for your situation and help you with venting and other considerations. Remember that all installation specifications are governed by local building codes and that a building permit will be required. Check with the building department to make sure your plans conform to regulations.

NOTE: The information shown here apply specifically to masonry fireplaces, but many are useful guidelines for gas fireplaces as well.

2. Build a hearth extension for a masonry fireplace at least 16 inches in front of the firebox opening and at least 8 inches to the sides of the firebox opening, if the firebox opening is less than 6 square feet.

3. Build a hearth extension for a masonry fireplace at least 20 inches in front of the firebox opening and at least 12 inches to the side of the firebox opening, if the firebox opening is 6 square feet or more.

4. Build a hearth extension for a factory-built fireplace according to the fireplace manufacturer’s instructions. The hearth extension size is often the same as for a masonry fireplace.

2. Provide at least 1 inch of clearance to the masonry firebox opening for every 1/8 inch that combustible material projects from the fireplace surround. This applies to materials within 12 inches of the fireplace opening. Example: locate 1-inch-thick fireplace mantel legs at least 8 inches from the fireplace opening. Example: locate greater than 12 inches from the fireplace opening any part of a fireplace mantel or mantel leg that is more than 11/2 inches thick.

3. Provide clearance to combustible materials for a factory-built fireplace according to the fireplace manufacturer’s instructions. The clearance is often the same as for a masonry fireplace.

2. Comply with all of the following requirements for installed spark arrestors: (a) make the unobstructed arrestor area at least four times the area of the flue it serves; (b) make the arrestor screen using heat- and corrosion-resistant material equal to 19-gauge galvanized steel or 24-gauge stainless steel; (c) build the arrestor screen so it does not pass 1/2-inch-diameter spheres and does not obstruct 3/8-inch-diameter spheres; (d) make the arrestor accessible for cleaning and make the cap removable to allow for flue cleaning.

2. Do not use a chimney as a gas appliance vent if any side of the chimney is exposed to the outdoors below the roofline. This means that a chimney must be completely enclosed within the house walls until it reaches the attic.

3. You may use a chimney as a vent for one draft hood-equipped gas water heater if the area of the chimney flue as at least as large as the area of the draft hood outlet and not more than seven times the area of the draft hood outlet.

4. Do not use a chimney as a vent for one fan-assisted, medium efficiency gas furnace.

5. Do not connect an appliance vent to a masonry chimney flue if the area of the appliance connector is larger than the area of the chimney flue.

6. Install a permanent label in a conspicuous location warning occupants if a chimney has been relined and warning them what types of appliances may be connected to the chimney.

7. Have gas appliance vents connected to masonry chimney flues according to the provisions for gas appliance vents in IRC Chapter 24.

2. Install doors with gaskets at fireplace openings.

3. Install a tight-fitting flue damper.

2. Provide combustion air from the outside for vented gas and oil fireplaces according to manufacturer’s instructions.

3. Locate the outside combustion air inlet at or below the firebox level. Cover the inlet with a screen having 1/4-inch mesh.

4. Install combustion air openings and ducts that have an area of at least 6 square inches and not more than 55 square inches. Use a combustion air duct that is designed for that purpose, or keep the duct at least 1 inch away from combustible materials within 5 feet from the firebox.

5. Locate the inside combustion air outlet in the back or side of the firebox or at hearth level and not more than 24 inches from the firebox opening.

6. Install a closure mechanism at the combustion air outlet.

Fireplaces designed to burn only gas are not really fireplaces. They are decorative gas appliances. Vented decorative gas appliances are more like a water heater than like a fireplace. Unvented decorative gas appliances are more like a gas range than like a fireplace. Install and use decorative gas appliances according to manufacturer’s instructions and IRC Chapter 24. Note that some jurisdictions do not allow unvented decorative gas appliances. Also note that manufacturers of unvented decorative gas appliances recommend limits on the duration of use.

Heating & Air Conditioning

Safety is the primary focus of code provisions governing heating and air conditioning systems. Improper appliance installation can cause the appliance to malfunction, creating a fire hazard as well as the potential for carbon monoxide poisoning. Fuel-burning appliances, such as gas and oil furnaces, must be installed in safe locations and must be provided with enough outside air to support fuel combustion. Vents for these appliances must be installed so that they do not ignite combustible materials and so that combustion gases are not circulated back into the building.

In this chapter you will learn about the safe installation of heating and air conditioning appliances and their associated venting equipment. You will also learn about how to identify improperly installed forced-air ducts that can increase your energy costs and decrease your appliance’s useful life.

HVAC Appliances

Heating, ventilation, and air conditioning systems are often referred to as a group by the term HVAC. This is because they share a common purpose: to keep the air in your home comfortable. All HVAC systems—even hot-water-based systems—rely on the flow of air to heat, cool, and ventilate your home.

Most homes today include two separate major appliances in the HVAC system: a furnace and a central air conditioning unit. In most cases, even when the AC has been retrofitted, the appliances share ductwork.

The information in this chapter is intended mostly for general education purposes and to assist with diagnosing system problems. Unless you are a very experienced DIYer, installing and servicing HVAC equipment is a job best left to professionals.

2. Do not locate appliances anywhere that is not approved by the manufacturer’s instructions.

3. Do not apply this provision to appliances powered only by electricity, such as heat pump air handlers and electric water heaters.

2. You may install vented room heaters, vented wall furnaces, vented decorative appliances, and decorative appliances listed for installation in vented, solid fuel-burning fireplaces (such as gas logs) in prohibited locations if the room satisfies combustion air volume requirements.

3. You may install one listed, wall-mounted, unvented room heater in a bathroom if the appliance has an oxygen depletion safety shutoff system, the appliance input rating is not more than 6,000 BTU/hour, and the bathroom satisfies combustion air volume requirements.

4. You may install one listed, wall-mounted, unvented room heater in a bedroom if the appliance has an oxygen depletion safety shutoff system, the appliance input rating is not more than 10,000 BTU/hour, and the bedroom satisfies combustion air volume requirements.

5. You may install appliances in an enclosure accessible from the prohibited locations if all combustion air is drawn directly from the outdoors and the enclosure is equipped with a self-closing door that is weather-stripped.

6. The standard combustion air volume requirement is at least 50 cubic feet per 1,000 BTU/hour appliance input rating. This standard volume requirement does not apply if the home is tightly sealed with a known air infiltration rate of less than 0.40 air changes per hour. Tightly sealed homes are rare.

2. Install radiant panels parallel to wood framing members, and fasten the panels to the surface of the framing members or mount the panels between framing members.

3. Install fasteners only in areas of the appliance’s radiant panel designed for fasteners. Install fasteners at least 1/4 inch away from a heating element.

4. Install radiant panels as complete units, unless listed and labeled for field modifications.

5. Do not install radiant panels on drywall unless the panel’s maximum operating temperature is not more than 125 degrees Fahrenheit.

2. Measure the elevation distance to the ignition source in the equipment, not to the bottom of the equipment (unless the ignition source is at the bottom of the equipment).

3. You may install appliances on the floor in rooms that are adjacent to a garage but do not have an opening into the garage.

4. You are not required to elevate the ignition source of flammable vapor ignition resistant (FVIR) gas water heaters. All new gas water heaters are FVIR (and have been for many years).

2. Install horizontal pipe sections with a uniform slope in the direction of the discharge point of at least 1/8 inch in 12 inches.

3. Use fittings, primers, cements, hangers, and other components that are compatible with the pipe material. Install the pipe according to the provisions in general codes.

4. Use pipe material use a pipe size that will accommodate the condensate temperature, pressure, and flow rate produced by the air conditioning system.

5. Install a trap in the primary condensate discharge pipe according to the appliance manufacturer’s instructions. The minimum trap depth is often about 2 inches.

6. You may use most water supply and drain pipes for condensate discharge pipes. The most common condensate discharge pipes are PVC, CPVC, and ABS.

7. Connect a condensate pump to the appliance it serves so that the appliance will not operate if the pump will not operate. This applies to pumps located in spaces such as attics and crawlspaces.

2. Install one of the following auxiliary condensate systems when an auxiliary condensate system is required: (a) Install an auxiliary drain pan under the evaporator coil. Use a pan that is at least 11/2 inches deep and at least 3 inches larger than the evaporator coil in both length and width. Construct the pan using either at least 0.0276-inch galvanized sheet metal or at least a 0.0625-inch, nonmetallic pan. Slope the pan toward the discharge pipe connection. Install the auxiliary discharge pipe using the same materials and methods as the primary discharge pipe. Terminate the auxiliary discharge pipe at a conspicuous point so that the occupants can see when the primary condensate discharge system is not functioning properly (a conspicuous point often means above a window). (b) Install a water level cutoff switch above the primary condensate discharge pipe where it connects to the evaporator coil and below the evaporator coil interior condensate pan overflow rim. Or, you may install the switch in the primary or secondary discharge pipes. The switch location should allow the switch to shut off the air conditioner before water overflows into the building.

HVAC Duct Installation

Improper duct installation and duct damage are common problems. Ducts that leak, have sharp bends, or sag reduce the volume of air that moves through the duct and increase the friction between the air and the duct walls. This causes the HVAC system to work harder and longer than necessary, wasting energy and money.

2. Use flexible ducts that are labeled at least every 36 inches with information, such as the manufacturer’s name and the R-value of the duct insulation.

3. Do not expose flexible ducts to direct sunlight, such as may occur under roof vents. Direct sunlight can damage the duct outer cover.

4. Extend flexible duct to its full length. Do not leave excess duct material in a duct run, and do not compress the duct.

2. Support flexible ducts at not more than 4-foot intervals. You may use a fitting or distribution plenum to provide initial flexible duct support.

3. Do not allow flexible duct to sag between supports more than 1/2 inch per foot.

4. Support bends in long horizontal runs of flexible duct at not more than one duct diameter on both sides of the bend.

5. Support bends in flexible duct that occur near the plenum connection. Allow flexible ducts to run at least several inches beyond a plenum connection before making a bend.

6. Provide independent support for duct fittings and distribution plenums. Support duct fittings at not more than 1 foot from the fitting.

7. Support vertical runs of flexible duct at more than 6-foot intervals.

2. Do not bend flexible ducts so that the bend radius at the centerline is less than one duct diameter.

3. Avoid changing the shape of the duct. The area of a round duct is greater than the area of the same duct compressed into an ellipse.

2. Connect flexible ducts to metal collars that are at least 2 inches long.

3. Splice two ducts together using a metal sleeve at least 4 inches long.

4. Use approved clamps and tape to secure nonmetallic flexible ducts to metal collars and sleeves.

5. Use approved tape and mastic to seal duct collars, plenums, and other fittings to ensure minimum air leakage.

2. You are not required to insulate ducts that are completely within conditioned space.

3. Seal ducts, furnaces, air handler, filter boxes, junction boxes, and fittings.

4. Verify duct and air handler sealing with a duct pressure test. You may perform this test during rough-in or after final installation of the HVAC system. Refer to the IRC for test requirements.

5. Do not use framing cavities, such as stud walls and floor framing, as HVAC ducts or plenums.

2. Do not locate a return register closer than 10 feet in any direction to an open combustion chamber or to a draft hood-equipped appliance. Common examples of these prohibited sources include a fireplace and a water heater.

3. Do not take more return air from a room or a space than is supplied to that room or space.

2. You may locate outdoor air intake openings closer than 10 feet horizontally to a contaminant source if the outdoor air intake opening is at least 3 feet below the contaminant source.

3. Do not locate outdoor air intake openings where objectionable odors, fumes, or flammable vapors may be present.

4. Locate outdoor air intake openings at least 10 feet above a public walkway or driveway.

5. Do not locate outdoor air intake openings at grade level next to a sidewalk, street, alley, or driveway.

6. Provide an automatic or gravity-operated damper for air intake systems that will close the damper when the system is not operating.

Combustion Air for Fuel-Burning Appliances

Fuel-burning appliances, such as gas furnaces, boilers, and water heaters, need air to support the fuel-burning (combustion) process. These appliances also need air for cooling, ventilation of the appliance, and for proper operation of the vent system that expels combustion byproducts outside. The air required to support operation of fuel-burning appliances is called combustion air.

Without adequate combustion air, incomplete fuel combustion may occur. Byproducts of incomplete fuel combustion can include carbon monoxide and soot that can damage the appliance and its vent. This is a health and safety hazard. Appliances operating without adequate combustion air can cost more to operate and maintain.

Do not confuse combustion air with the similar term “makeup air.” Makeup air replaces air that is exhausted by clothes dryers, exhaust fans, fireplaces, and similar devices.

2. Provide combustion air for direct vent and for Category II, III, and IV gas appliances according to the appliance manufacturer’s instructions. Do not apply combustion air requirements to these appliances. Category II appliances do not currently exist. Category III and IV appliances include medium and high-efficiency gas appliances that operate with positive vent pressure.

3. Do not apply combustion air requirements to fireplaces and fireplace stoves. Refer to other general codes for fireplace combustion air requirements.

2. You may use unobstructed stud and joist spaces as combustion air ducts if only one required fireblock is removed.

3. Terminate combustion air ducts in unobstructed space that allows free air movement.

4. Do not open combustion air ducts into more than one room or enclosure.

5. Do not use the same combustion air duct for both the upper and lower duct openings.

6. Do not install a screen on any combustion air duct opening in the attic.

7. Do not slope horizontal combustion air ducts downward toward the source of combustion air. Make the duct level or slope it toward the appliance.

8. Do not use the space in a masonry, metal, or factory-built chimney that surrounds a chimney liner, gas vent, plastic piping, or other devices as a combustion air duct.

9. Locate the lowest point of an exterior combustion air opening at least 12 inches above exterior grade.

Vents for Fuel-Burning Appliances

A vent is generally a vertical component, such as a metal pipe, that conducts combustion products from a gas- or oil-burning appliance to the outdoors. A vent for a single appliance begins at the fitting where the vent connector, if any, connects to the vent. A common vent for multiple appliances begins at the highest connector fitting. If a vent is located directly over the appliance draft hood or flue collar, or if the vent connects directly to the appliance, then the vent begins at the appliance and there is no vent connector.

A vent connector is a pipe that connects an appliance to its vent or flue. A vent connector is required if the appliance is not located directly under its vent. A vent connector for a Category I gas appliance may be a listed vent material, such as a Type B vent; a listed flexible vent connector; or a field-constructed, single-wall metal pipe made of at least 28-gauge galvanized steel. While a vent connector is part of the venting system, it is not the vent itself.

Common types of vents and vent connectors include the Type B vent used with most gas appliances, Type L vents used with oil-burning appliances, flexible connectors used with gas appliances, and single-wall connectors that may be used with either gas or oil-burning appliances.

The material in this section deals with vents for low- and medium-efficiency appliances. Fewer of these appliances are being installed in favor of high-efficiency appliances and appliances with special venting requirements. Examples of special-vented appliances include high-efficiency gas furnaces (vented with plastic pipe), sidewall-vented appliances, and appliances using positive pressure vent systems. Do not apply the material in this section to special-vented appliances.

Venting of special-vented appliances is governed by the appliance manufacturer’s instructions. These instructions will vary by manufacturer and by appliance model. Thus, the only way to determine if a special-vented appliance vent is installed properly is to compare the appliance vent installation to the instructions for the appliance in question.

Vents for special-vented appliances are frequently improperly installed. Proper vent (and combustion air) installation is important for proper and safe appliance operation. It is a good idea to evaluate and confirm vent installation for special-vented appliances.

2. Terminate a masonry chimney at least 3 feet above the roof and at least 2 feet above any part of the building within 10 feet of the chimney. Measure termination height above the roof from the highest point where the chimney penetrates the roof to where the flue exits the chimney. This provision also applies to many factory-built chimneys. Confirm factory-built chimney termination height using the manufacturer’s installation instructions.

3. Use Table 25 to determine the minimum height above the roof of a Type B gas vent not more than 12 inches in diameter. Measure termination height above the roof from the highest point where the vent penetrates the roof to the bottom of the listed cap. For thick roof-covering materials, such as tile, measure from the tile to the bottom of the listed cap.

4. Do not use Table 25 if a Type B vent is closer than 8 feet to a vertical side wall, gable end, or similar vertical obstruction. Terminate these vents at least 2 feet higher than the highest point where the vent penetrates the roof and at least 2 feet higher than any part of the roof or building within 10 feet horizontally.

5. Terminate all vents and chimneys at least 8 feet horizontally from operable windows unless the vent is at least 3 feet above the window.

6. Do not install a vent terminal where a door can swing within 12 inches horizontally from the vent terminal. This will apply mostly to direct vent terminals.

7. Do not install a decorative shroud or surround at a vent termination unless the shroud or surround is listed for use with the specific venting system and unless the shroud or surround is installed according to manufacturer’s instructions. This prevents an unlisted shroud from interfering with the drafting characteristics of the vent system.

2. Verify venting requirements using manufacturer’s instructions. Some manufacturers of appliances such as unvented gas fireplaces recommend limiting the duration of use and/or opening a window while the appliance is operating.

Plumbing System

Plumbing projects are popular among do-it-yourselfers, so naturally there’s a strong demand for information on home plumbing subjects to make sure home projects are accomplished correctly. Water supply pipes must be properly sized, supported, and connected to avoid water leaks and low water flow at fixtures.

Wastewater drain pipes must be properly installed to avoid water leaks and sewage backups. Traps and vents must be correctly hooked up in drain lines.

Finally, in this chapter you’ll learn basic requirements for installing water supply pipes and water drain and vent pipes, as well as for installing common plumbing fixtures, such as water heaters, faucets, tubs, and showers.

The Home Plumbing System

Water Supply Piping

Water supply pipes carry hot and cold water throughout a house. In homes built before 1960, the original supply pipes were usually made of galvanized steel. Newer homes have supply pipes made of copper. In most areas of the country, supply pipes made of rigid plastic or PEX are accepted by local plumbing codes.

Water supply pipes are made to withstand the high pressures of the water supply system. They have small diameters, usually 1/2 inch to 1 inch, and are joined with strong, watertight fittings. The hot and cold pipes run in tandem to most parts of the house. Usually, the supply pipes run inside wall cavities or are strapped to the undersides of floor joists. They are sometimes run in the attic in warm climates.

Hot and cold water supply pipes are connected to most fixtures and appliances. Fixtures include sinks, tubs, and showers. Some fixtures, such as toilets and hose bibbs, are supplied only by cold water. Appliances include dishwashers and clothes washers. A refrigerator icemaker uses only cold water. Tradition and codes say that hot water supply pipes and faucet handles are found on the left-hand side of a fixture, with cold water on the right.

Because it is pressurized, the water supply system is prone to leaks. This is especially true of galvanized iron pipe, which has limited resistance to corrosion.

Water flow is primarily a function of the size, type, and installation of water supply pipes and supply fixtures. You can achieve more flow in a larger pipe than you can in a smaller pipe. Different pipe materials, such as PEX and copper, have different flow rates for the same size pipe. Many current water supply fixtures have flow restriction devices that limit the water flow rate to conserve water.

Water pressure is primarily a function of the force behind the water as it enters the piping system. A system with too little water pressure may not provide sufficient water flow when multiple supply fixtures are being used. Too much water pressure, exceeding 80 psi, can cause premature failure of water supply pipes and fixtures. A pressure regulator is recommended to reduce excessive water pressure.

2. Do not exceed 80 psi static water pressure.

3. Install an approved pressure regulator at the main water supply connection to the dwelling if the static pressure exceeds the maximum. Measure the water pressure to the point where the water supply enters the building as closely as possible.

2. Common water distribution pipe materials used in modern residential construction include those in Table 28.

3. You may use other approved materials if allowed by local codes. Copper, CPVC, and PEX are the most common water distribution pipes.

2. You may use flared fittings to make connections between soft copper water tubing and valves and fixtures. Use approved fittings and a flaring tool to form and connect these joints.

3. Use fittings and crimping tools approved by the tubing manufacturer when connecting PEX and other water supply materials to each other. Most homeowners should not attempt to install PEX and similar materials using these fittings and tools because this requires training and experience.

4. Use push-fit fittings only with copper tubing, CPVC, and PEX. Do not use push-fit fittings with other pipe and tubing, such as polybutylene.

5. You may use mechanical fittings to connect pipes made from the same materials and pipes made from different materials. Install the fittings according to manufacturer’s instructions.

2. Use a flexible water connector that is approved for the application. Example: do not use a connector intended for a clothes washing machine to connect a water heater to the hot water supply pipe.

3. Do not run flexible water connectors through walls, ceilings, and floors or in concealed spaces.

4. Do not use flexible water connectors as a substitute for permanent water supply pipes.

2. Support and install pipes so they can move with the normal expansion and contraction of the piping system without scraping or rubbing against supports or framing materials.

3. Use pipe supports that will carry the weight of the pipe and that are sufficiently wide to prevent crimping and distortion of the pipe.

4. Use pipe supports that will not cause corrosion or galvanic reaction between the pipe and the support. Example: do not use steel supports with copper pipe or copper supports with cast-iron pipe.

5. Provide rigid sway bracing at changes in pipe direction more than 45 degrees for pipe sizes at least 4 inches in diameter.

6. Provide horizontal and vertical support for pipes according to Table 30.

2. Use shield plates at least 1/16-inch thick.

3. Apply these rules to pipes running through holes and notches in framing materials. While not required by most general codes, it is a best practice to protect pipes (other than cast iron or galvanized steel) that are closer than 11/2 inches from the edge of framing materials. The most common example of such pipes is a pipe installed parallel to the edge of a stud or joist.

4. Protect copper plumbing pipe from corrosion where it passes through masonry or concrete. You may use pipe wrapping material designed for this purpose, or you may enclose the pipe in a sleeve.

5. Protect gas pipes, other than steel, with shield plates if the pipe is closer than 11/2 inches from the edge of studs, joists, rafters, or similar framing members. Extend the shield plate at least 4 inches below top plates and at least 4 inches above bottom plates.

2. Install water service pipe at least 12 inches deep or at least 6 inches below the frost line.

3. Verify minimum water service and building sewer pipe depth with the local building official.

4. Apply these requirements only to areas with a winter design temperature of 32 degrees Fahrenheit or less.

2. You may install a freeze-proof yard hydrant below ground if the water supply to the hydrant is protected with a backflow preventer and the yard hydrant is permanently labeled as a “non-potable water source.”

2. You need not install a stop-and-waste valve on a frost-proof hose bibb if the stem extends into an open heated or semi-conditioned area of the building.

Drain, Waste & Vent Piping (DWV)

Drainpipes use gravity to carry wastewater away from fixtures, appliances, and other drains. This wastewater is carried out of the house to a municipal sewer system or septic tank.

Drainpipes are usually plastic or cast iron. In some older homes, drainpipes may be made of copper, galvanized steel, or lead. Because they are not part of the supply system, lead drainpipes pose no health hazard. However, lead pipes are no longer manufactured for home plumbing systems.

Drainpipes have diameters ranging from 11/4 inches to 4 inches. These large diameters allow waste to pass through easily.

Traps are an important part of the drain system. These curved sections of drainpipe hold standing water, and they are usually found near any drain opening. The standing water of a trap prevents sewer gases from backing up into the home. Each time a drain is used, the standing trap water is flushed away and replaced by new water.

In order to work properly, the drain system requires air. Air protects trap from being drained. To allow air into the drain system, drainpipes are connected to vent pipes. All drain systems must include vents, and the entire system is called the drain-waste-vent (DWV) system. One or more vents, located on the roof, provide the air needed for the DWV system to work.

2. Do not use fittings that contain ledges, shoulders, or reductions that may retard or obstruct drainage flow.

3. Install fittings that maintain a 2 percent slope and are approved for use where installed. Example: do not use a vent tee in a drainage pipe where water flows.

4. Do not use threaded connections in pipes where the threads run on the inside of the pipe and could retard or obstruct drainage flow.

5. Do not drill, tap, burn, or weld drainage, sewer, or vent pipes. Example: do not drill into a vent pipe to insert the discharge hose from a water softener.

6. Do not use the following types of joints and connections: cement or concrete, mastic or hot-pour bituminous, fittings not approved for the specific type of pipe or installation, joints between different pipe diameters made with elastomeric rolling O-rings, solvent-cement joints between different types of plastic pipe, and saddle fittings.

2. Install galvanized steel drainage pipe at least 6 inches above the ground.

2. You may use a 4-inch-by-3-inch reducing closet bend to connect to the closet flange.

2. Provide vanity sinks, bidets, and similar fixtures with tailpieces and traps at least 11/4 inches.

2. Provide slip joints with access of at least 12 by 12 inches.

2. Do not use a double sanitary tee to receive discharge from back-to-back toilets or from fixtures or appliances with pumping action (such as washing machines and dishwashers). You may use a double sanitary tee if the distance between the center of the closet flange and the inlet of the sanitary tee is at least 18 inches.

2. You may not connect wet vented fixtures to the low heel inlet of a heel inlet quarter bend.

3. You may use the side inlet of a quarter bend to change the flow direction when the inlet is horizontal (side facing), but not when the inlet is vertical (facing up). The side inlet may accept drainage flow from any fixture except a toilet. Side and heel inlets are usually 11/2- or 2-inch openings, and you may not connect a toilet to any opening less than (<) 3 inches.

4. You may connect a dry vent to the quarter bend side or heel inlet only when the inlet is vertical (facing up). You may connect a dry vent to a quarter bend side or heel inlet when the inlet is horizontal (side facing) only when the entire quarter bend fitting is used as part of a dry vent.

2. You may use solvent cement to join ABS pipes above and below ground. Clean and dry pipes and fittings before applying solvent cement to all joint surfaces. Make the joint while the solvent cement is wet. Use solvent cement that complies with ASTM D 2235. Do not use PVC cement with ABS pipe.

3. You may use threaded joints for Schedule 80 and heavier ABS pipe. The threads should be NPT type. Do not place threads on the pipe’s interior.

2. You may use approved branded couplings to join galvanized steel pipes. Install the branded couplings according to manufacturer’s instructions.

2. You may use solvent cement to join PVC pipes above and below ground. Clean and dry pipes and fittings before applying primer to all joint surfaces. Apply primer that complies with ASTM F 656 if required by your local jurisdiction. Apply solvent cement that complies with ASTM D 2564. Make the joint while the solvent cement is wet. Do not use ABS cement with PVC pipe.

3. You may use threaded joints for Schedule 80 and heavier PVC pipe. The threads should be NPT type. Do not place threads on the pipe’s interior.

2. Use an approved brass ferrule with a caulked joint or a mechanical compression joint when joining copper tubing to cast-iron pipe.

3. Use a brass converter fitting or a dielectric fitting when joining copper tubing to galvanized steel pipe.

2. Install pipe not more than 21/2 inches in diameter with at least a 1/4 unit in 12 units (2 percent) slope.

3. Install pipe at least 3 inches diameter with at least a 1/8 unit in 12 units (1 percent) slope.

NOTE: A 4-inch-by-3-inch closet bend fitting is not classified as a reduction in size.

2. Install a cleanout within 10 feet of the building drain and building sewer junction. You may install this cleanout inside or outside the building. Make this cleanout accessible. Measure the 10 feet along the developed length of the pipe from the cleanout fitting to the building drain and sewer junction.

3. Install a cleanout at every change of pipe direction more than 45 degrees when the direction change uses one fitting. When multiple direction changes occur in one pipe run, only one cleanout is required, spaced not more than 40 feet apart. This provision applies to the building drain, building sewer, and horizontal branch drains.

2. You may install a cleanout in a vertical stack that is one pipe size smaller than the stack pipe size.

2. Do not conceal cleanouts with permanent finishing materials.

3. Extend underground cleanouts to or above finished grade. Do not extend cleanouts above surfaces where they may become trip hazards or where they may be damaged by traffic.

2. Make cleanouts gas and liquid tight.

Plumbing Vents

To understand the purpose of plumbing vents, you must first understand the purpose of plumbing traps. A trap is required for all fixture drains connected to the DWV pipes. A trap can be a separate fitting, such as a P-trap for a sink or a shower, or it can be part of the fixture, such as the trap in a toilet. A trap maintains a water seal that keeps noxious and potentially explosive sewer gas in the DWV pipes and away from the air in the home. Water flows into a fixture and through a trap when you use a fixture. When you stop using the fixture, some of the water remains in the trap and recharges the trap’s water seal.

When water flows in a pipe near a trap, the suction caused by the flowing water can create enough negative pressure at the trap to pull the water out of the trap. This is sometimes called siphoning the trap, because it is similar to what happens when you use a hose to siphon fuel out of a fuel tank. If the trap looses its water seal, the home is open to the flow of sewer gas.

A plumbing vent protects the trap’s water seal by allowing air into the DWV pipes. The air provided by the vent replaces the air that is drawn along with the flowing water. This replacement air reduces the suction and protects the trap. Without properly sized and installed vents, the DWV system will not function as intended.

2. Terminate at least one vent outdoors. Connect the outdoor vent to the building drain or to a branch or extension of the building drain. The branch or extension cannot be an island fixture vent.

2. Install horizontal branch vent pipes at least 6 inches above the flood rim level of the highest fixture served by the vent.

2. Connect the roughed-in vent to the vent system or provide another approved means to terminate the roughed-in vent.

3. Label the roughed-in vent pipe to indicate that it is a vent.

2. Extend vent pipes at least 7 feet above any roof used as a balcony, observation deck, or similar accessible walking surface.

2. Increase the diameter of exterior vent terminal pipes to at least 3 inches, beginning at least 1 foot below the roof or inside the wall.

3. These provisions apply only where the 97.5 percent winter design temperature is less than 0 degrees Fahrenheit. Obtain this information from IRC Chapter 3 and from your local building official.

2. Use caulk to make vent pipes extending through a wall watertight.

2. Locate plumbing vent terminations running through a side wall at least 10 feet from the lot line and at least 10 feet above the highest grade within 10 feet horizontally from the vent termination.

3. Locate plumbing vent terminations at least 7 feet above a roof used for recreational purposes, such as an observation deck or sunbathing.

4. Protect side-wall vent terminations from entry by birds or rodents.

5. Do not locate vent terminations directly under the building’s overhang if the overhang contains soffit vents.

2. The table does not apply to self-siphoning fixtures, such as toilets. No fixture drain length limitations apply to these fixtures.

2. Connect the top of the fixture drainpipe to the vent fitting above the trap weir. This provision does not apply to toilet fixture drains.

2. Increase the vent pipe diameter by at least one pipe size over the entire length of the vent pipe when the vent’s developed length is greater than 40 feet.

2. Number of fixtures: Use an individual vent to protect only one fixture.

3. Fixture location: Use an individual vent to protect one fixture located anywhere in the structure.

4. Individual vent connection location: Connect the individual vent on the fixture drain of the fixture being vented or at the fixture drain connection to the drainage system.

5. Fixture drain length to vent connection: Use Table 33 to determine the maximum distance between the fixture trap weir and the individual vent fitting.

6. Individual vent pipe size: Use at least a 11/4-inch pipe or a pipe at least 1/2 the size of the drainpipe being vented, whichever is larger.

2. Number of fixtures: Use a common vent to protect only two fixtures.

3. Fixture location: Use a common vent only for fixtures located on the same floor level. You may connect the fixture drains at different vertical levels if the fixtures are on the same floor level.

4. Common vent connection location: You may connect the common vent where the fixture drains intersect. You may connect the common vent downstream from where the fixture drains intersect only when the fixture drains connect to the branch drainpipe at the same horizontal level.

5. Fixture drain length to vent connection: Use Table 33 to determine the maximum distance between each fixture trap weir and the common vent fitting.

6. Common vent pipe size: Use at least 11/4 inches of pipe or a pipe at least 1/2 the size of the drainpipe being vented, whichever is larger, for the common vent.

2. Number of fixtures: Use a wet vent to protect not more than two toilets, two bathtubs or showers, two lavatory sinks, or two bidets.

3. Fixture location: Use a wet vent only for approved bathroom fixtures located on the same floor level.

4. Wet vent connection location: (a) Begin the wet vent with an individual or common vent for a lavatory, bidet, shower, or bathtub. This vent does not need to be at the first wet vented fixture in a horizontal wet vent. This vent must be at the first wet vented fixture in a vertical wet vent. End the wet vent at the last wet vented fixture connection to the wet vented pipe. (b) Do not connect more than one fixture upstream from the beginning individual or common vent in a horizontal wet vent. (c) Connect each fixture individually to the wet vented pipe. Do not connect two or more fixtures together and connect that branch drain to the wet vented pipe.

5. Horizontal wet vent fixture drain connection location: (a) Connect each individual fixture drain horizontally to a horizontal wet-vented pipe. Example: you may not install a wye fitting vertically and connect a fixture drain to the vertical opening of the wye in a horizontal wet vent. You may install the wye horizontally and connect the horizontal fixture drain to the horizontal opening of the wye. (b) You may connect a fixture drain vertically to a horizontal wet-vented pipe if you install a dry vent on the vertically connected fixture. Example: you may install a wye fitting vertically if you connect an individual vent to the fixture. (c) Do not connect any fixtures to the horizontal wet-vented pipe other than those fixtures being wet-vented. You may connect other fixtures to the horizontal pipe downstream after the wet vent ends. Example: do not connect a bedroom bar sink to a wet-vented pipe.

6. Vertical wet vent fixture drain connection location: (a) Connect all toilet fixture drains at the same vertical level. (b) Connect fixture drains from bathtubs, showers, lavatory sinks, and bidets at or above where the toilet fixture drains connect to the vertical wet vent.

7. Fixture drain length to wet-vented pipe: Use Table 33 (see here) to determine the maximum distance between each fixture trap weir and the fixture drain fitting at the wet-vented drain pipe. You may use individual and common vents to protect any fixture where the fixture drain length limit is a problem.

8. Wet vent pipe size: (a) Use a dry vent that is at least a 11/4-inch pipe or a pipe at least 1/2 the size of the wet-vented pipe, whichever is larger, for the individual or common vent that begins the wet vent. (b) Use Table 34 to size the horizontal and vertical wet-vented drainage pipe. You may not connect a toilet to a drainage pipe smaller than 3 inches regardless of what is allowed in the table.

2. Use an island fixture vent to protect any number of approved fixture types.

3. Use an island fixture vent only for fixtures located in the same island and on the same floor level.

4. Pipe configuration: (a) Extend the loop portion of the island fixture vent vertically to above the drain outlet of the fixture being vented before extending the horizontal and/or vertical downward portion.(b) Use drainage fittings and pipe slopes for any portion of the vent below the fixture flood rim level. Do not use vent fittings or slope the vent pipe as a vent below the fixture flood rim level.(c) Connect the downward portion of the vent loop downstream from where the fixture drain connects with the horizontal drainage pipe. Make the connection using a full size fitting. (d) Provide cleanouts at the downward portion of the loop vent and in the vertical portion of the vent pipe before it connects to the exterior vent pipe.

5. Dry vent connection location: (a) Connect the dry vent to the drainage system using a full size fitting. Connect the dry vent to a vertical drain pipe or the top half of a horizontal drain pipe. (b) Extend any dry vent at least 6 inches above the flood rim level of the highest fixture being vented before any connection to the outside vent.

6. Fixture drain length to vent connection: Use Table 33 to determine the maximum distance between the fixture trap weir and the fixture drain connection to the island vent.

7. Vent pipe size: Use at least a 11/4 inches pipe or a pipe at least 1/2 the size of the drain pipe size being vented as the dry portion of the vent, whichever is larger.

2. You may use air admittance valves to vent individual vents, branch vents, circuit vents, and stack vents. Use individual and branch-type air admittance valves to vent fixtures that are on the same floor level and that are connected to a horizontal branch drain.

3. Use air admittance valves that are rated for the vent size to which the valve is connected.

4. Locate individual and branch-type air admittance valves at least 4 inches above the horizontal branch drain or fixture drain being vented.

5. Locate stack-type air admittance valves at least 6 inches above the flood rim level of the highest fixture being vented.

6. Locate the air admittance valve within the vent’s developed length limits.

7. Locate air admittance valves in attics at least 6 inches above insulation.

8. Provide air admittance valves with access and adequate ventilation.

9. Install air admittance valves within 15 degrees of vertical, and do not install air admittance valves outdoors unless allowed by the manufacturer’s instructions.

10. Do not use an air admittance valve as the vent for a sewage ejector tank unless the vent system for the tank is designed by a qualified engineer.

11. Look for the UPC symbol on the air admittance valve. Air admittance valves without this symbol are for use only in manufactured homes. They may not be used in homes governed by the IRC.

12. Do not install air admittance valves outside unless allowed by manufacturer’s instructions. Do not install them outside to evade vent clearance requirements to air intake openings.

Plumbing Traps

2. Do not install separate traps on toilets, urinals, and other fixtures that have traps in the fixture itself.

3. Do not install a trap that is larger than the drainage pipe into which the trap discharges. Example: do not connect a 2-inch trap to a 11/2-inch pipe on the discharge side of the trap.

2. Install floor drain traps that have a deep seal (near 4 inches) design or a trap primer. Connect trap primer valves above the trap seal level.

2. Protect traps from freezing.

3. Provide access to traps with slip joints at the trap inlet or outlet.

4. Do not install more than one trap per fixture.

5. Limit the vertical distance between the fixture drain outlet and the trap weir to not more than 24 inches.

6. Limit the horizontal distance between the fixture drain outlet and the center of the trap inlet to not more than 30 inches. Note that this 30-inch horizontal distance may be eliminated or not enforced in some jurisdictions. Verify if this provision applies in your jurisdiction.

Plumbing Appliances & Fixtures

The installation and hookup of appliances that are part of your home plumbing system is the part of the plumbing process that DIYers are most likely to attempt. The information in this section provides a good general backdrop for making plumbing hookups, but be sure to read the manufacturer’s installation recommendations carefully. As always, manufacturer instructions take precedence over codes.

Water heaters for primary duty in residences range in size from 30 gallons to 65 gallons. For a family of four, a 40- or 50-gallon model should be adequate. While you don’t want to run out of hot water every morning, you also don’t want to pay to heat more water than you use. Base your choice on how well your current water heater is meeting your demand.

2. Do not install fuel-fired water heaters in bedrooms or bathrooms unless the water heater is installed in a sealed enclosure where combustion air does not come from the living space. This restriction does not apply to direct vent water heaters.

3. You may provide access to water heaters located in attics or crawl spaces through bedrooms, bathrooms, or their closets if ventilation of the bedroom, bathroom, or closet complies with codes.

2. Install the temperature relief or T&P valve on the top of the water heater or on the side of the water heater within 6 inches of the top. Do not install an extension pipe between the water heater and the T&P valve.

3. Do not install a check valve or shutoff valve anywhere that might interfere with the operation of the relief valve or the flow of water or steam from the discharge pipe.

2. Install the discharge pipe so hot water and steam will not cause personal injury or property damage if the relief valve discharges.

3. Install the discharge pipe so that any leaking from the pipe outlet is readily observable by the building occupants.

4. Use a discharge pipe that is at least as large as the relief valve opening. The size is usually 3/4 inch in diameter. Use 1-inch-diameter pipe or tubing if insert fittings are installed in the discharge pipe. PEX tubing is the most common example of this situation.

5. Run the discharge pipe full size to the floor, to an indirect waste receptor (such as a floor drain) inside the building, to the water heater drip pan, or outside the building. If the area is subject to freezing, terminate the discharge pipe through an air gap into an indirect waste receptor located inside the building. You may use other discharge points in areas subject to freezing, if approved by the local building official.

6. Slope the discharge pipe so that it drains by gravity from the relief valve to the discharge point.

7. Do not connect the discharge pipe directly to the building’s drain, waste, and vent system. Leave an air gap between the discharge pipe and the floor, ground, or other termination point.

8. Do not install a trap or a valve or a threaded outlet in the discharge pipe.

9. Terminate the discharge pipe through an air gap not more than 6 inches and not less than 11/2 inches above the floor.

10. Do not connect more than one appliance to a discharge pipe.

2. Use a drip pan at least 11/2 inches deep and made with at least 24-gauge galvanized steel or other approved materials. Use a pan with a size and shape to catch all leaks and condensation from the water heater. Do not install a plastic pan under a gas-fired water heater unless the pan is listed for installation under a gas-fired water heater.

3. Run the discharge pipe to an indirect waste receptor (such as a floor drain) or to the outside of the building. Terminate the pipe not more than 24 inches or not less than 6 inches above the ground or a waste receptor, such as a floor drain.

4. You are not required to install a pan under a replacement water heater if no pan is currently installed.

2. Install toilets that use an average of not more than 1.6 gallons per flush.

3. Provide the toilet with an adequate supply of water. Control the water supply with an automatic device (such as a float valve) that will refill the toilet tank after each flush and completely stop the flow of water to the tank when the tank is full. The device should also supply enough water to refill the toilet.

4. Install toilets with a flush valve seat in the toilet tank that is at least 1 inch above the flood level of the toilet bowl. An alternate design (used by low-profile one-piece toilets) is acceptable. This design closes the flush valve when the toilet is clogged and prevents water from flowing back into the tank.

5. Provide toilet tanks with an overflow pipe or mechanism that is sufficient to prevent the tank from flooding if the fill valve malfunctions.

6. Provide access to all parts in the toilet tank for repair and replacement. Do not install permanent counter tops or similar obstructions that restrict access to the tank.

7. Use toilet seats made of smooth, non-absorbent material properly sized for the toilet bowl.

8. Use corrosion-resistant screws, nuts, bolts, and washers to secure toilets to the closet flange.

2. Locate the backflow preventer at least 1 inch above the opening of the overflow pipe. Fill valves with all parts below the tank water line usually violate this provision.

2. Use non-corrosive bolts and an approved gasket (O-ring) or other approved setting compound to secure the toilet and closet flange and to make the seal watertight.

2. Install a water-hammer arrestor where required to control water flow and reduce the possibility of water hammer. A water-hammer arrestor may be used near a quick-closing valve, such as in a clothes washing machine.

2. Provide a door or access panel large enough to allow service personnel to repair and replace the pump. The door size will depend on where the pump is located relative to the door. The door may have to be larger than the specified minimum size if the pump is located far away from the door.

3. Make the access opening at least 12 inches by 12 inches if the manufacturer does not specify an opening size. Make the access opening at least 18 inches by 18 inches if the pump is located more than 2 feet away from the opening. Do not place obstructions, such as tub support framing and pipes, between the access opening and the pump.

4. Locate the circulation pump above the crown weir of the trap.

5. Install circulation pipes and pump drain line so that they are self-draining and retain minimum possible water after using the tub.

6. Install whirlpool bathtub motors on a GFCI protected circuit. Do not use the bathroom receptacle circuit for this purpose.

7. Install a copper bonding wire at least #8 AWG connecting all metal pipes, pump motors, and other electrical equipment associated with the whirlpool bathtub. Do not bond grounded double insulated whirlpool bathtub pump motors.

2. You may provide a shower with a finished minimum dimension of at least 25 inches if the finished area is at least 1,300 square inches.

3. Provide shower compartment access of at least 22-inch finished width.

4. Swing hinged shower doors out from the shower stall. Hinged doors may swing into the shower stall if they also swing out. Sliding shower doors are also allowed.

2. Install a shower curb or threshold (when used): (a) at least 1 inch below the sides and back of the receptor; and (b) at least 2 inches and not more than 9 inches above the top of the drain.

3. Slope the shower floor at least 1/4 unit in 12 units (2-percent slope) and not more than 1/2 unit in 12 units.

4. Use a flanged shower floor drain that provides a watertight seal at the floor.

5. Use hot-mopped felt, sheet lead, sheet copper, approved plastic liner material, or approved trowel-applied liquid material when installing a site-built shower receptor. Plastic liners (such as chlorinated polyethylene and plasticized polyvinyl chloride) are the most common modern site-built liner materials.

6. Extend the lining material at least 2 inches beyond or around the rough jambs of the shower receptor. Extend the lining material at least 2 inches above the finished threshold or curb.

7. Attach the lining material to an approved backing. Nail or perforate the lining at least 1 inch above the finished threshold. Seal joints in plastic lining material according to manufacturer’s instructions.

8. Install an approved flanged shower drain that is equipped with weep holes into the drain and is equipped with a flange that makes a watertight seal between the lining material and the drain.

2. Do not install a valve downstream from an atmospheric vacuum breaker.

3. Install a reduced pressure backflow preventer if chemicals are introduced into the irrigation system.

Electrical System

Home wiring is a very popular do-it-yourself subject that is fundamentally hazardous. When it comes to electricity, mistakes and accidents do pose threats, including fire, injury, and death. Therefore, safety is the primary focus of the electrical code provisions.

In this chapter you will find many of the rules governing safe installation of electrical wires, electrical equipment—including conduit, electrical receptacles, switches, lights, and other fixtures. Use this information to inspect your wiring and make sure it all conforms to code. If it does not, or if you are unsure about it, have a professional electrician upgrade your electrical system.

• Electrical Grounding & Bonding

• Electrical Branch Circuit Requirements

• Electrical Receptacle Installation

• Ground-Fault (GFCI) & Arc-Fault (AFCI) Protection

• Junction Boxes, Device Boxes & Enclosures

• Switch Installation

• Light Fixture Installation

• Satellite Dishes, Television & Radio Antennas

• Broadband Cable Wiring

Understanding Electrical Circuits

An electrical circuit is a continuous loop. Household circuits carry current from the main service panel, throughout the house, and back to the main service panel. Several switches, receptacles, light fixtures, or appliances may be connected to a single circuit.

Current enters a circuit loop on hot wires and returns along neutral wires. These wires are color coded for easy identification. Hot wires are black or red, and neutral wires are white or light gray. For safety, most circuits include a bare copper or green insulated grounding wire. The grounding wire conducts current when wires or equipment are malfunctioning and helps reduce the chance of severe electrical shock. The service panel also has a bonding wire connected to any metal water pipes.

If a circuit carries too much current, it can overload. A fuse or a circuit breaker protects each circuit in case of overloads.

Current returns to the service panel along a neutral circuit wire. Current then leaves the house on a large neutral service wire that returns it to the utility pole transformer.

2. Provide at least 60-amp service to an accessory structure. Exceptions to the 60-amp minimum service exist for one- and two-circuit 120-volt service to accessory structures.

3. You may use the following wire sizes as a feeder when the load at the accessory structure is limited to one or two 15- or 20-amp, 120-volt branch circuits: (a) use at least #10 AWG copper or #8 AWG aluminum wire if the accessory structure has not more than two 15 or 20 amp, 120 volt branch circuits; (b) use at least #14 AWG copper or #12 AWG aluminum if the accessory structure has only one 15 amp, 120 volt branch circuit and use at least the same size feeder wire as used for the branch circuit.

4. Provide an equipment grounding wire with the feeder wires, and refer to the grounding requirements section if there are at two or more branch circuits in the accessory structure.

2. Recess metal knockout covers in non-metallic boxes and conduit bodies at least 1/4 inch from the surface of the box or conduit body.

3. Cover open outlet boxes with a blank cover, a blank plate, or fixture canopy. Switch plates and receptacle plates do not provide complete closure for electrical boxes.

4. Ground metal covers and plates.

2. Locate the circuit identification on the face of the panelboard enclosure or on the inside panelboard door.

2. Provide a clear working space around electrical enclosures that is at least 36 inches deep, at least 30 inches wide (or as wide as the enclosure if it is wider than 30 inches), and at least 78 inches high (or as high as the enclosure if it is higher than 78 inches). Measure the clear working space from any exposed energized parts or from the cover in front of covered energized parts.

3. The enclosure should have enough clearance that the enclosure door can be opened at least 90 degrees.

4. Do not locate equipment, pipes, and ducts that are not associated with the electrical system directly above or below an indoor enclosure from the floor to the ceiling or 6 feet above the enclosure, whichever is less.

5. Do not locate anything not associated with the electrical system directly above or below an outdoor enclosure from grade to 6 feet above the enclosure. Examples include hose bibbs, exhaust duct terminations, and appliance vents.

6. Provide access to the clear working space around the enclosure (cabinet). Do not block access with shelves, workbenches, or other difficult to move objects.

7. Install electrical panels and circuit breakers and fuses so that the circuit breaker handle or fuse is not more than 79 inches above the floor or ground when the center of the handle is in its highest position.

8. You may install electrical panels rated not more than 200 amps in existing buildings where the working space height is less than 78 inches. This does not apply to new construction.

2. Cover spliced wires with material equal to the original insulation. This does not include electrical tape or similar materials.

3. For splice wires that will be buried in the ground, use only devices listed for direct burial and install them according to manufacturer’s instructions.

4. Provide access to spliced wires unless the splice and splicing device are specifically allowed to be concealed. Access is usually provided by an accessible, covered junction box.

5. Do not place wire splices in a raceway unless the raceway has a removable cover.

2. Use only inhibitors and antioxidant compounds that are approved for splicing aluminum and copper wires. These materials should not degrade or damage the wires, wire insulation, or equipment. Read and follow manufacturer’s instructions.

2. Extend wires at least 6 inches beyond where the wires emerge from the raceway or cable sheathing. Example: NM cable enters a single residential switch box with 1 inch of intact sheathing (outer cover). Begin the 6 inches measurement where the sheathing ends. The cable should extend at least 7 inches from the rear of the box. The NM cable should also extend at least 3 inches beyond the outside edge of the box.

2. Connect more than one wire to a terminal only if the terminal is identified to accept multiple wires. Example: general codes require one wire per terminal for the grounded (neutral) wires and allow two or more same-gauge wires per terminal for the equipment grounding wires. Example: many circuit breakers allow only one hot (ungrounded) wire per circuit breaker terminal.

3. Connect aluminum wires to terminals only if the terminal is identified to accept aluminum wires.

2. Use wires with green insulation, or wires with green insulation and at least one yellow stripe as equipment grounding wires. You may use uninsulated (bare) wires as equipment grounding wires in most circuits.

3. You may use any color other than white, gray, or green as hot (ungrounded) wires. The common colors are red and black.

4. You may use a wire with white or gray insulation as a hot (ungrounded) wire if the wire is part of a cable (such as NM) and if you permanently mark it as a hot (ungrounded) conductor at all places where the wire is visible and accessible. This marking is usually done by wrapping the end of the wire with black or red electrical tape. The marking must encircle the insulation.

2. Connect equipment grounding wires together in all device boxes. Do not rely on any device, such as a receptacle or light fixture, to provide the connection for the equipment grounding wire in any circuit.

3. Install a wire (called a pigtail) between the connected wires and any device in the box.

2. Label the service disconnecting equipment as such. The label must be permanent and clearly marked.

3. Use only service disconnecting equipment listed and labeled for that purpose. The electric meter and meter enclosure are not service equipment. Do not rely on removing the electric meter to disconnect electrical service.

4. The service disconnecting equipment should be installed in a readily accessible place where every building occupant has access.

5. The service disconnecting equipment may be located outside the building or inside the building as close as possible to where the service entrance conductors enter the building. Check with the local building official for information concerning your area. Fifteen feet is one typical maximum, but the distance may be less in some jurisdictions.

6. Service disconnecting equipment should not be located in bathrooms.

7. Service disconnecting switches or circuit breakers should not be installed more than 79 inches above the floor or ground.

2. Provide at least 8 feet of vertical clearance between service drop wires and a roof not designed for regular pedestrian traffic, with a slope less than 4 inches in 12 inches. Access to such a roof would usually be by a ladder, through a window, or through a maintenance hatch.

3. You may reduce the 8-foot vertical clearance to at least 3 feet of vertical clearance if: (a) the voltage between wires is not more than (≤) 300 volts and (b) the roof is guarded or isolated; or if (c) the roof slope is at least 4 inches in 12 inches. Many residential service drops comply with this exception.

4. Provide at least 10 feet of vertical clearance between service drop wires and a roof designed for regular pedestrian traffic. Access to such a roof would usually be by stairs or by a door, and the roof edges would be protected by a guard.

5. Provide at least 18 inches of vertical clearance between service drop wires and a roof if: (a) the wires pass only over the overhang portion of the roof, and (b) not more than 6 feet of wire pass over not more than 4 lineal feet of roof surface measured horizontally, and (c) the wires enter a through-the-roof mast or terminate at an approved support.

6. Maintain all required clearances above the roof for at least 3 feet in all directions from the roof’s edge.

2. Provide at least 10 feet of vertical clearance between service drop wires and areas or sidewalks accessed by pedestrians only.

3. Provide at least 12 feet of vertical clearance between service drop wires and residential property and driveways.

4. Provide at least 18 feet of vertical clearance between service drop wires and public streets, alleys, roads, or parking areas subject to truck traffic.

Electrical Grounding & Bonding

One of the important purposes of grounding and bonding can be summarized in this simple rule: Electricity wants to return to its source and will take all available paths to get there. When the electrical system is working as intended, electricity enters through the hot (ungrounded) wire, does its work, and returns to its source (usually the utility’s transformer) through the neutral (grounded) wire.

When electricity finds its way out of the intended path, things get dangerous. Example: a rat sits on copper water pipe and chews through the insulation on electrical cable exposing the hot (ungrounded) wire. After electrocuting the unfortunate rat, the exposed wire lands on the water pipe. If the water pipe is connected without electrical interruption to the electricity’s source (through bonding), the electricity thinks that the water pipe is the neutral (grounded) wire and happily starts flowing through the water pipe. This is a ground fault. The electric current should quickly rise to the point where it trips a circuit breaker or blows a fuse, clearing the fault.

But what if the water pipe is not bonded? Perhaps a water softener has been added to the system, interrupting the electrical continuity of some or all of the water pipe. In our example, the water pipe is still energized, but there is no way for the electricity to return to its source; that is, until someone grabs a metal water faucet handle and is standing on the ground or on some conducting surface. At that time, the electricity finds its path to its source through the person. The person is injured or killed.

When trying to understand grounding and bonding, think like electricity. If metal can become energized, however unlikely that is, you must assume that it will become energized. Bonding metal together and connecting the metal to ground in an approved manner lets you, not the electricity, decide how electricity will flow in a fault condition.

2. The neutral (grounded) wire should not be connected to ground at any other place downstream from the service equipment grounding point. An exception to this rule exists when two buildings are supplied by one electric service.

3. All metal parts of the electrical system should be connected to the neutral (grounded) wire. This includes service equipment and panelboard cases, any metal electrical conduit or tubing, and all metal pipes in the building (such as metal water and gas pipe).

2. You are not required to use this procedure if there is only one branch circuit in the second building and if the new feeder cable for that one branch circuit contains an equipment grounding wire.

2. All grounding electrodes that may be available at a building should be bonded together. General codes do not require that all possible types of grounding electrodes be installed. They require that if a grounding electrode is installed, it must be connected (bonded) to all other grounding electrodes and to the neutral (grounded) wire.

3. A bonding jumper at least as large as the grounding electrode wire should be used to connect (bond) the grounding electrodes. Bonding jumpers may be connected between grounding electrodes at any convenient point.

4. The grounding electrode wire may be connected at any convenient grounding electrode. Protect grounding electrode wires that are subject to physical damage with approved conduit or tubing, such as intermediate metallic conduit or PVC conduit.

5. Protect grounding electrode wires that are smaller than #6 AWG with approved conduit regardless of whether the wire is subject to physical damage.

6. Install a grounding electrode wire based on the size of the service entrance conductors. Most grounding electrode wires should be #6 or #8 copper.

7. Metal gas pipe should never be used as a grounding electrode.

2. You must consider all underground water pipe that satisfies the previous conditions as a grounding electrode and connect (bond) underground water pipe to all other grounding electrodes.

3. Do not connect a grounding electrode wire to any interior metal water pipe at a point that is more than 5 feet from where the underground water pipe enters the building. Do not use any interior metal water pipe that is more than 5 feet from where the water pipe enters the building as a conductor for a grounding electrode. Example: do not connect the grounding electrode wire at a water heater cold water pipe if the pipe is more than 5 feet from where the water pipe enters the building.

4. Do not use underground metal water pipe as the only grounding electrode. Install at least one other type of grounding electrode and connect (bond) it to the underground metal water pipe.

5. Install bonding jumper wires around devices that might interrupt electrical continuity. Such devices include water meters, water pressure reducers, water softeners, and water filtration systems.

2. You may use a stainless steel, zinc-coated or copper-coated steel, or copper rod that is at least 5/8-inch diameter and at least 8 feet long as a grounding electrode.

3. Do not use aluminum as rod and pipe electrodes.

4. Do not use one rod or pipe electrode as the only grounding electrode. Install at least one other grounding electrode of any approved type. Bond all grounding electrodes together. This provision does not apply if the rod or pipe electrode has a resistance to earth of not more than 25 ohms.

2. Encase the reinforcing bar or wire in at least 2 inches of concrete. Place the bar or wire in either the horizontal or vertical part of the concrete that is in direct contact with the ground. Do not place a moisture barrier between the concrete and the ground.

3. You may use wire ties or similar means to connect (bond) reinforcing bars together to achieve the 20-foot minimum length.

4. Concrete encased electrodes are also called ufer grounding electrodes after the man who designed this grounding electrode system.

2. Do not install aluminum or copper-clad aluminum grounding electrode wires within 18 inches of the ground when the wire is installed outside.

2. You may use a listed metal strap ground clamp to connect indoor communications equipment grounding electrode wires to a grounding electrode.

3. Make accessible the connection point of grounding electrode wires and bonding jumpers to grounding electrodes. The connection point need not be accessible for buried or concrete encased grounding electrodes.

4. Clean grounding electrode wire connection points and all clamps and fittings of non-conductive materials, such as paint.

2. Make bonding jumpers long enough to permit removal of the equipment and maintain electrical continuity.

3. Use bonding jumpers that are at least the same wire size as the grounding electrode wire.

2. Use a bonding jumper or wire that is at least the same wire size as the grounding electrode wire.

3. Make the bonding connection point accessible.

2. You may use the equipment grounding wire that serves the gas appliance as the bonding wire. Number 10 AWG copper wire is the largest equipment grounding wire for almost all residential branch circuits. This means that: (a) a separate bonding wire between the gas pipe and the service equipment is usually not necessary (although some jurisdictions require one anyway), and (b) #10 AWG copper wire is usually the largest required gas pipe bonding wire.

3. Make the bonding connection point accessible.

2. Install the bonding connection at the first length of steel or copper pipe before the CSST. This is usually at the gas meter or where the propane pipe enters the home.

3. Some CSST is arc-resistant and does not need a separate bonding connection. This CSST usually has a black jacket. Verify CSST bonding requirements using manufacturer’s instructions and by contacting your building inspector.

Electrical Branch Circuit Requirements

Every electrical circuit has its limits. Among the more basic tasks in evaluating your existing wiring system or planning a system expansion is to identify which loads will be drawing from which circuits so you can establish what each circuit capacity will need to be. In addition to letting you plan the circuits wisely, specific load knowledge lets you create a more balanced service panel, lessening the chances that you’ll trip breakers.

2. Use only 120-volt branch circuits to supply residential light fixtures, receptacles for plug-and-cord connected loads not more than 1,440 watts, and motor loads less than .25 horsepower.

3. You may use either 120- or 240-volt branch circuits to supply one plug-and-cord connected or one permanently wired appliance rated more than 1,440 watts. This means that branch circuits rated more than 120 volts are effectively limited to serving a single receptacle or permanently wired fixed equipment.

4. Do not connect one or more fixed devices that in total exceed 50 percent of a multiple outlet branch circuit’s amperage rating. Fixed devices do not include light fixtures. This means that all fixed devices (such as a permanently wired disposal or hot water circulating pump) on a multiple outlet branch circuit may not exceed 7.5 amps (about 900 watts) on a 15-amp multiple outlet branch circuit and may not exceed 10 amps (about 1,200 watts) on a 20-amp multiple outlet branch circuit.

2. Do not use a 30-amp branch circuit to serve loads other than a fixed device, such as a water heater, or a single plug-and-cord connected device, such as a welder.

2. Do not install a window or through-wall air conditioner on a 15- or a 20-amp multiple outlet branch circuit if the air conditioner’s total rated current load is more than 50 percent of the branch circuit’s rating (80 percent for dedicated circuits).

2. Provide a separate dedicated branch circuit for the kitchen range hood receptacle, if a range hood receptacle is installed. It is recommended, but not required, that this be a 20-amp, 120-volt branch circuit.

2. You may provide each bathroom with its own dedicated 20-amp, 120-volt branch circuit. In this case, you may use the branch circuit to supply other bathroom outlets, such as light fixtures and exhaust fans.

2. Provide at least one receptacle outlet for each vehicle storage bay in attached garages and in detached garages that are provided with power. General codes do not specify the type or rating of the receptacle.

2. Use a two-pole overcurrent device or two single pole devices that are connected by an approved handle tie to protect most multiwire branch circuits. Do not connect circuit breaker handles with nails, wires, or other unapproved handle tie substitutes.

3. Use wire ties or similar devices to group all ungrounded (hot) and grounded (neutral) wires of each multiwire branch circuit in the cabinet where the circuit originates.

2. Protect NM and UF cable using RMC, IMC, EMT, or Schedule 80 RNC when the cable is subject to physical damage. Extend the protection at least 6 inches above the floor when the cable runs through the floor.

3. Protect NM and UF cable using nail guards or other approved physical protection when the cable is installed: (a) through holes, notches, or grooves that are closer than 11/4 inches to the edge of a stud or joist; (b) in notches and grooves in places such as drywall, plaster, and under carpet, unless the groove or notch is deeper than 11/4 inches; (c) through holes in metal framing (use grommets or bushings); and (d) parallel to the edge of a stud, joist, or furring strip when the cable is closer than 11/4 inches to the edge of the framing member.

4. Support NM, UF, AC, and MC cable every 41/2 feet. Use wire staples or other approved fasteners to support vertical runs of NM, UF, AC, and MC cable. Staple the cable only on the flat edge. Note that wiring methods need not always be secured to be considered supported. Cable run across the tops of joists and truss chords is usually considered supported without being secured to the joists. Cable must be secured to be considered supported when it is run vertically and when it is run on the sides and bottoms of framing members.

5. Secure NM and UF cable not more than 8 inches from boxes and terminations that do not have cable clamps. This includes most plastic boxes. Secure NM and UF cable not more than 12 inches from boxes and terminations that have cable clamps. This includes most metal boxes. Measure the support distance from where the cable sheathing ends in the box, not from the box itself.

6. Use NM cable only in dry locations that are indoors and not within concrete or masonry that is exposed to the ground. Do not use NM cable in conduit that is buried in the ground. Buried conduit is considered a wet location. You may use UF cable in wet locations, including outdoors and underground if it is not subject to damage.

2. You may allow not more than 36 inches between the last support and a light fixture or other equipment that may need to be moved for service or replacement.

2. You need not protect electrical cables in accessible attics when the cables are installed: (a) running parallel to the edge of the framing and at least 11/4 inches from the edge of the framing or (b) in holes that are at least 11/4 inches from the edge of the framing.

Electrical Receptacle Installation

Whether you call them outlets, plug-ins, or receptacles, these important devices represent the point where the rubber meets the road in your home wiring system. From the basic 15-amp, 120-volt duplex receptacle to the burly 50-amp, 240-volt appliance receptacle, the many outlets in your home do pretty much the same thing: transmit power to a load.

Learning the essential differences between receptacles does not take long. Amperage is the main variable, as each receptacle must match the amperage and voltage of the circuit in which it is installed. A 15-amp circuit should be wired with 15-amp receptacles; a 20-amp circuit needs 20-amp receptacles (identified by the horizontal slot that Ts into each tall polarized slot). A 20-amp multi-receptacle circuit may use either 15- or 20-amp receptacles. Receptacles for 240-volt service have unique slot configurations so you can’t accidentally plug in an appliance that’s not rated for the amperage in the circuit. Some receptacles can be wired using the push-in wire holes, but this is not recommended. Some receptacles provide built-in, ground-fault circuit protection, tripping the circuit breaker if there is a short circuit or power surge. These are easy to identify by reset and test buttons.

2. Mount receptacles in boxes that are recessed from the wall by seating the receptacle’s extension ears at the top and bottom of the receptacle against the wall surface.

3. Mount receptacles in boxes that are flush with the wall by seating the receptacle’s mounting yoke or strap against the box.

4. Do not allow the receptacle to move when a plug is inserted. This can, over time, cause wires to loosen, allow arcing, and cause a fire.

5. Install receptacle faceplates so that the plate completely covers the receptacle and so that the faceplate is flush against the wall. No gaps should exist between the receptacle and the faceplate or between the faceplate and the wall.

6. Install receptacles so that the face of the receptacle is either flush with or projects out from a nonmetallic faceplate.

7. Install receptacles so that the face of the receptacle projects out from a metallic faceplate at least (≥) 1/64 inch.

8. Install receptacles so that the wiring terminals are not exposed to physical contact.

2. You do not need to install tamper-resistant receptacles if the receptacle: (a) is located more than 66 inches above the floor, (b) is part of a light fixture or appliance, or (c) is a single or duplex dedicated appliance receptacle into which one or two not easily movable appliances will be plugged.

2. You may replace a non-grounding type receptacle (2-slot) with a grounding type receptacle (3-slot) if: (a) the replacement receptacle is a GFCI receptacle and (b) the cover plate is labeled “No Equipment Ground.”

3. You may replace a non-grounding type receptacle (2-slot) with a grounding type receptacle (3-slot) if: (a) the replacement receptacle is supplied by a GFCI protected circuit and (b) the cover plate is labeled “GFCI Protected and No Equipment Ground.”

4. Use 1, 2, and 3 above only if no equipment grounding wire is available in the receptacle box. You must use a grounding type receptacle, and you must use the equipment grounding wire if it is available.

5. You may run an equipment grounding wire to the nearest box containing an equipment grounding wire if all hot, neutral, and grounding wires originate at the same panelboard.

6. Do not connect the neutral wire to the receptacle grounding lug. These “bootleg grounds” are a dangerous code violation.

2. Install the required interior receptacles so that any point along a wall is not more than 6 feet from a receptacle. When measuring a wall, do not include operable doors, fireplaces, closet interiors, or similar openings, or fixed cabinets that do not have countertops or similar work surfaces. A wall begins at the edge of an opening and continues around any corners to the next opening. Walls include fixed (not sliding) panels in doors that are at least 2 feet wide. Walls include partial height walls that serve functions, such as room dividers, and walls that form breakfast bars and similar bar-type counters. Walls include guards and railings at balconies, raised floors, and other areas where furniture could be placed.

3. Locate floor receptacles intended to serve as required interior receptacles not more than 18 inches from the wall. You may install interior floor receptacles at any safe place, but you may count only receptacles not more than 18 inches from the wall among the required receptacles.

4. Install receptacles not more than 66 inches above the finished floor. You may install receptacles at any height, but you may count only receptacles not more than 66 inches above the finished floor among the required receptacles.

2. Install kitchen countertop receptacles so that all points along the countertop wall are not more than 2 feet from a receptacle. A wall begins at the edge of an opening or appliance, and continues around any corners, and ends at the next opening or appliance. Include windows when measuring the wall unless the window is above a sink or cooking appliance.

3. Install receptacles behind a sink or cooking appliance located along a straight wall if the countertop behind the sink or cooking appliance is at least 12 inches wide. Install receptacles behind a sink or cooking appliance located along a wall corner if the countertop behind the sink or cooking appliance is at least 18 inches deep.

4. Install receptacles not more than 20 inches above the countertop. You may install receptacles at any height, but you may include only receptacles not more than 20 inches above the countertop among the required kitchen countertop receptacles.

5. Do not include among the required kitchen countertop receptacles: (a) receptacles located in appliance garages, (b) receptacles dedicated for a fixed-in-place appliance, or (c) receptacles not readily accessible for use by small appliances.

6. Do not install receptacles face up on work surfaces unless the receptacle is listed for this type of installation.

7. Locate the receptacle for the dishwasher in a space adjacent to the dishwasher, if installing a dishwasher receptacle. This does not apply to a hard-wired dishwasher outlet.

2. Install kitchen countertop receptacles along any wall space above an island or peninsula countertop. Such wall space occurs when an island or peninsula is installed at a partial height wall.

3. You may install receptacles not more than 12 inches below an island or peninsula countertop if the countertop is flat and there is no wall space above the countertop or if the countertop is designed for access by the physically impaired. Do not install the required kitchen island or peninsula receptacle below a breakfast bar or other countertop that extends more than 6 inches beyond the supporting base.

2. Install receptacles behind a sink or cooking appliance if the countertop behind the sink or cooking appliance is at least 12 inches wide or at least 18 inches deep if the sink or cooking appliance is installed in a corner.

3. Install kitchen countertop receptacles along any wall space above an island or peninsula countertop. Such wall space occurs when an island or peninsula is installed at a partial height wall.

4. You many install receptacles not more than 12 inches below an island or peninsula countertop if the countertop is flat and there is no wall space or cabinet above the countertop.

5. Do not install receptacles face up on countertops or similar work surfaces.

2. Do not install receptacles face up on work surfaces.

2. Provide GFCI protection for all 15- and 20-amp, 120-volt receptacles in the laundry area. This includes any dedicated receptacle for the clothes washing machine.

2. Install at least one GFCI protected, 15- or 20-amp, 120-volt receptacle within the perimeter of any balcony, deck, or porch that: (a) is accessible from inside the home and (b) has a usable area of at least 20 square feet. Locate the receptacle not more than 78 inches above the balcony, deck, or porch.

2. You are not required to provide GFCI protection to a receptacle that is dedicated to serving a fire or security alarm system.

2. You may not serve any other outlets from the circuit serving garage receptacles except for readily accessible receptacles located outside the house. This means that garage lights and exterior lights and receptacles must be served by one or more separate circuits.

3. Do not connect other outlets to a receptacle circuit that is intended for charging an electric vehicle. These receptacle circuits are often 240 volts.

Ground-Fault (GFCI) & Arc-Fault (AFCI) Protection

2. Kitchen. Install GFCI protection on the outlets that supply dishwashing machines. This includes receptacles and hard-wired connections.

3. Bathroom receptacles. Install GFCI protection on all 120-volt receptacles located in bathrooms. This applies to all receptacles regardless of where they are located in the bathroom and includes receptacles located at countertops, inside cabinets, and along bathroom walls. This also applies to bathtubs and shower stalls that are not located in a bathroom. Install GFCI protection on all circuits serving electrically heated floors in bathrooms, kitchens, and around whirlpool tubs, spas, and hot tubs.

4. Garage and accessory building receptacles. Install GFCI protection on all 120-volt receptacles located in garages and grade-level areas of unfinished accessory buildings.

5. Exterior receptacles. Install GFCI protection on all 120-volt receptacles located outdoors. This does not apply to receptacles that are dedicated for deicing equipment and are located under the eaves. This does apply to holiday lighting receptacles located under the eaves.

6. Basement receptacles. Install GFCI protection on all 120-volt receptacles located in unfinished basements. An unfinished basement is not intended as habitable space and is limited to storage and work space.

7. Crawl space outlets. Install GFCI protection on all 120-volt outlets and lights located in crawl spaces. Receptacles in crawl spaces are not required unless equipment requiring service is located there.

8. Sink receptacles. Install GFCI protection on all 120-volt receptacles that are located within 6 feet of the top inside edge of a sink. This includes wall, floor, and countertop receptacles.

9. Boathouse receptacles. Install GFCI protection on all 120-volt receptacles located in boathouses. Install GFCI protection on all 120-volt and 240-volt receptacles that serve boat hoists.

10. Spas, tubs, and other circuits requiring ground-fault protection. Install GFCI protection on all circuits serving spa tubs, whirlpool tubs, hot tubs, and similar equipment. Refer to the general codes for more information about receptacles serving these components.

11. Install GFCI circuit breakers and receptacles so that they are readily accessible.

2. You may provide AFCI protection for the entire branch circuit by installing a combination-type AFCI circuit breaker in the electrical panel where the branch circuit originates.

3. You may provide AFCI protection to a branch circuit using several different combinations of branch-circuit type AFCI circuit breakers and branch-circuit type AFCI receptacles. Refer to general codes or your local building inspector for details about these alternate methods.

4. Provide AFCI for branch circuits that are modified, replaced, or extended. You may use either of the following methods: (a) install a combination-type AFCI circuit breaker in the electrical panel where the branch circuit originates or (b) install a branch-circuit type AFCI receptacle at the first receptacle in the existing branch circuit.

5. Install AFCI circuit breakers and receptacles so that they are readily accessible.

Junction Boxes, Device Boxes & Enclosures

All electrical boxes are available in different depths. A box must be deep enough so a switch or receptacle can be removed or installed easily without crimping and damaging the circuit wires. Replace an undersized box with a larger box using Table 42 the Electrical Box Fill Chart (see here) as a guide. The NEC also says that all electrical boxes must remain accessible. Never cover an electrical box with drywall, paneling, or wall coverings.

2. Extend NM cable sheathing at least 1/4 inch into a non-metallic box knockout opening.

3. Secure NM cable, conduit, and tubing to each box. You may secure NM cable with cable clamps inside the box or with compression tabs provided where the cable enters the box. You do not need to secure NM cable to a standard single-gang box (21/4 by 4 inches) mounted in a wall or ceiling if you fasten the cable not more than 8 inches from the box and if the sheathing enters the box at least 1/4 inch. Measure the 8 inches along the length of the sheathing, not from the outside of the box.

2. You may use other boxes to mount light fixtures on walls if the fixture weighs less than 6 pounds and is secured to the box using at least #6 screws.

3. Support light fixtures weighing at least 50 pounds independently from the light fixture box unless the box is labeled as being designed to support a heavier light fixture. You may use the light fixture box to support light fixtures weighing less than 50 pounds. Note that ceiling fans are not light fixtures.

2. Use the cubic inch volume printed on the box or provided in the box manufacturer’s instructions to determine box volume. Do not attempt to measure the box volume. Do not estimate box volume from the volume of similar size boxes. You will probably not get the same volume as provided by the manufacturer.

3. Use Table 41 to determine the volume units required by wires, devices, and fittings in a box.

2. Install boxes in walls and ceilings made of wood or other combustible material so that the box’s front edge is flush with the finished surface or projects from the finished surface. You may use an extension ring, plaster ring, or similar device to extend the box to the finished wall surface. Mechanically secure the extension device to the box.

3. Cut openings for boxes in drywall and plaster so that the opening is not more than 1/8 inch from the perimeter of the box.

2. Protect screws inside boxes so that the threads will not damage the wires.

3. Wood braces used to support boxes must be at least 1 × 2 inches.

4. Use “cut-in” or “old work” retrofit boxes only if they have approved clamps or anchors that are identified for the location where they are installed.

2. Install a watertight seal between a flush-mounted receptacle and its faceplate. This will require a gasket or sealant between the finished surface (such as stucco, brick, or siding) and the faceplate.

2. Install a watertight seal between a flush-mounted receptacle and its faceplate. This will require a gasket or sealant between the finished surface (such as stucco, brick, or siding) and the faceplate.

2. Support boxes that do not contain switches, receptacles, or light fixtures by using at least two lengths of conduit threaded wrench-tight into the box. Secure the conduit not more than 3 feet from the box if the conduit enters from different sides of the box. Secure the conduit not more than 18 inches from the box if the conduit enters from the same side of the box. Example: if the conduit enters the box from the top and bottom of the box, then secure the conduit not more than 3 feet from the box. Example: if the conduit enters the box from only the top or only from the bottom, then secure the conduit not more than 18 inches from the box.

3. Support boxes that contain switches or receptacles or light fixtures by using at least two lengths of conduit threaded wrench-tight into the box. Secure the conduit not more than 18 inches from the box.

4. You may use RMC or IMC metal conduit to support light fixtures under certain conditions. Refer to the IRC for the exceptions.

2. You may run NM cable into the top of a surface-mounted cabinet through an accessible rigid raceway under certain conditions. Refer to IRC Chapter 39 for the conditions.

2. Use switches that are rated at least 80 percent of a motor’s full load current rating.

3. Install switches that have at least the same current rating as the circuit breaker or fuse protecting the branch circuit when the switch controls plug-and-cord connected equipment either by switching the receptacle or by switching a permanently connected cord. Example: a switch controls half of a receptacle in a bedroom. If the branch circuit is 20 amps, the switch should be rated at 20 amps or more.

4. Run the grounded (neutral) wire of a general purpose branch circuit to the switch box when the switch controls lighting loads. Refer to the IRC for exceptions that may occur in some unusual conditions.

2. Use switches that clearly indicate whether the switch is in the ON or OFF position. This does not apply to three-way and four-way switches. This requirement is frequently waived when rocker type switches are used.

2. Install a barrier to guard against contact with energized parts.

2. Locate switches in readily accessible places.

2. You may replace an existing ungrounded switch with another ungrounded switch if the wiring method has no equipment grounding wire. Protect these ungrounded switches that are located not more than 8 feet vertically or 5 feet horizontally from the ground or from grounded metal objects by: (a) installing a non-combustible and non-conductive faceplate using nonmetallic screws or (b) using a switch with a non-metallic strap or yoke or (c) installing GFCI protection on the circuit.

2. Do not locate switches in shower or tub spaces unless the switch is part of a listed tub or shower assembly.

2. Mount switches in boxes that are flush with the wall by seating the switch’s mounting yoke or strap against the box.

3. Do not allow the switch body to move when the switch is operated. This can, over time, cause wires to loosen, potentially causing arcing and a fire.

Light Fixture Installation

2. Install at least one wall switch to control stairway lights if the stairs have at least (≥) 6 risers. Install a switch at: (a) each floor and (b) each landing that provides access to an interior or exterior entry opening.

2. Locate a switch for the light at the usual point of entry into the area. You may use a pull-chain-controlled light if the light is located at the usual point of entry into the area. This means that if the light is not at the entrance to the area, the light must be switched at the entrance.

2. Do not use the screw shell of a light fixture to support anything that weighs more than 6 pounds or is more than 16 inches in any dimension.

2. Use insulation contact (IC) rated recessed lights when the recessed parts are installed in an insulated attic. IC rated recessed lights may not require clearance to insulation or to combustible materials.

3. Provide at least 3 inches of clearance between insulation and recessed lights that are not labeled as being insulation contact (IC) rated. Do not install insulation above non-IC rated recessed lights.

2. Use only lights labeled SUITABLE FOR WET LOCATIONS when installing lights that may be subject to direct contact with water. Refer to the definition of wet location (see here).

3. Use lights labeled either SUITABLE FOR WET LOCATIONS or SUITABLE FOR DAMP LOCATIONS when installing lights in damp locations. Refer to the definition of damp location (see here). Light fixtures, including ceiling fans, intended for indoors may not be installed in either wet or damp locations.

2. Support ceiling fans weighing more than 70 pounds independently from the box.

2. Use light fixtures that are listed for damp locations if the fixture is: (a) located within the tub or shower area and (b) within 8 feet from the top of the tub rim or shower threshold.

3. Use light fixtures that are listed for wet locations if the fixture is: (a) located within the tub or shower area, (b) within 8 feet from the top of the tub rim or shower threshold, (c) subject to shower spray.

Closet storage area: Clearances to light fixtures required by this IRC Section are between light fixtures and the closet storage area. The closet storage area is a space consisting of a hanging rod storage area and a shelf storage area. The required clearance applies to both areas. The clearances to light fixtures apply whether or not shelves or hanging rods are currently installed in the closet. This means that if a shelf or rod could be installed on a clothes closet wall, you must assume that one will be installed and that the clearances to light fixtures apply.

Hanging rod storage area: This area begins at the closet floor and ends 6 feet above the closet floor or at the highest hanging rod, whichever is higher. The hanging rod storage area includes all of the space within 24 inches horizontally from the back and sides of the closet walls.

Shelf storage area: This begins 6 feet above the closet floor or at the highest hanging rod, whichever is higher, and ends at the closet ceiling. The shelf storage area includes all of the space within 12 inches horizontally from the back and sides of the closet walls or within the width of the shelf, whichever is wider.

2. Provide at least 12 inches between surface mounted incandescent or LED light fixtures and the closest point of the closet storage area.

3. Provide at least 6 inches between recessed incandescent and LED light fixtures and the closest point of the closet storage area.

4. Provide at least 6 inches between fluorescent light fixtures and the closest point of the closet storage area.

5. You may install surface-mounted fluorescent and LED light fixtures within the closet storage area if the fixture is identified for use within the area.

2. Do not run or conceal flexible cords in walls, ceilings, floors, or raceways.

3. Do not splice or tap flexible cords.

4. Provide power to flexible cords through an attachment plug. Do not hard-wire flexible cords directly to a power source.

5. Do not use flexible cords as a substitute for permanent wiring.

Satellite Dishes, Television & Radio Antennas

This material applies to receiving antennas, such as satellite dishes, and traditional radio and television antennas. It does not apply to cable TV system wiring, and it does not apply to network-powered broadband communication system wiring. This material also applies to radio transmission antennas and towers, such as those used by amateur radio operators.

2. Do not attach or secure (guy) large antennas to chimneys, including framed and brick veneer chimneys. These chimneys are not designed to bear the loads imposed by large antennas. Consult a qualified contractor or chimney sweep before attaching or securing large antennas to chimneys.

3. Provide clearance between antennas and masts and electric power wires so that if the antenna falls, it is unlikely to fall on the electric power wires.

2. Provide at least 2 feet of clearance between outdoor, aboveground antenna wires and cables and electric power lines that can swing freely.

3. Provide at least 4 inches between outdoor antenna wires and cables and most residential electric power wires when both are secured so that they cannot move.

4. Provide at least 12 inches of clearance between underground antenna wires and underground cables and electric power wires.

5. Provide at least a 2-inch clearance between indoor antenna wires and cables and indoor electric power wires.

2. Install a grounding/bonding wire between the coaxial cable shield and an approved grounding/bonding point. You must ground/bond both the coaxial cable shield and any metal antenna mast.

3. Use at least #10 AWG copper wire or #17 copper clad steel wire as the grounding/bonding wire for receiving equipment only. You may use a #8 AWG aluminum or copper-clad aluminum grounding/bonding wire for receiving equipment only if it is not in contact with masonry, and is not installed in a corrosive environment, and is installed at least 18 inches above the ground at all points, including at the connection to the grounding/bonding point.

4. Use at least #10 AWG copper, bronze, or copper-clad steel as the grounding/bonding wires for transmitting/receiving stations. Use a larger wire if the lead-in wires are larger than #10 AWG. Insulation is not required on any grounding/bonding wire. You may use solid or stranded grounding/bonding wires for transmitting or receiving stations.

5. Run the grounding/bonding wire in as straight a line as possible to an approved grounding point.

6. Connect the grounding/bonding wire(s) to one of the following approved grounding/bonding points: (a) the intersystem bonding connection terminal; (b) the building’s grounding electrode, grounding electrode wire, or other metal part of the building grounding electrode system; (c) a metal water service pipe not more than 5 feet from where the water service pipe enters the building; (d) the service equipment cabinet or non-flexible metal service equipment raceway; or (e) the other system grounding/bonding connection described in the IRC.

7. Do not connect the antenna mast or coaxial cable to its own ground rod unless the ground rod is bonded to the building grounding electrode system using at least #6 AWG copper wire.

8. Secure and support the grounding/bonding wire by fastening it to the building or other substantial structure. Insulating supports are not required.

9. Protect the grounding/bonding wire if it is exposed to physical damage. Use a wiring method, such as metallic conduit, that is approved for use in physical damage environments.

10. Bond (connect) both ends of any metallic conduit and tubing used to protect the grounding/bonding wire to the bonding/grounding wire.

2. Install the listed connector so that it is both physically and electrically connected to the grounding point. This means removing paint, lacquer, rust, and other non-conductive material before attaching the listed connector to the grounding point.

3. Connect not more than one grounding wire to a listed connector unless the connector is listed to accept more than one wire.

4. Use a listed connector that is compatible with both the grounding point and the grounding wire material. Example: an iron or steel clamp is not compatible with a copper water pipe. Both materials will corrode over time.

Broadband Cable Wiring

This material applies to network-powered broadband communication system wiring. These systems usually deliver television, telephone, Internet, and similar services. They operate at up to 150 volts and 100 watts. This material does not apply to standard cable TV system wiring, and it does not apply to satellite TV antenna wiring. Some new communication systems use fiber-optic cables. This article does not apply to fiber-optic cables.

2. Avoid installing outdoor, aboveground broadband communication cables near electric power wires that can swing freely. Electric power wires include wires on overhead power poles, overhead service drop wires, and any electric power wires running between buildings. Provide at least 12 inches of clearance between outdoor, above-ground broadband communication cables and electric power lines that can swing freely. Increase clearance to at least 40 inches at the power pole.

3. Provide at least 4 inches between outdoor broadband communication cables and most residential electric power wires when both are secured so that they cannot move.

4. Measure the vertical clearance between overhead broadband cables and the ground, walkway, driveway, or street beginning at the lowest hanging point of the cables and ending at the surface under the lowest point.

5. Provide at least 91/2 feet vertical clearance between broadband cables and finished grade, sidewalks, or platforms accessed by pedestrians only.

6. Provide at least 111/2 feet vertical clearance between overhead broadband cables and residential property and driveways.

7. Provide at least 151/2 feet vertical clearance between overhead broadband cables and public streets, alleys, roads, or parking areas subject to truck traffic.

8. Provide the same clearance between overhead broadband cables and swimming pools, spas, and hot tubs as for electrical wires.

9. Provide at least 8 feet vertical clearance between broadband cables and most low-slope roofs.

10. Provide at least 18 inches of vertical clearance between broadband cables and roof overhangs if not more than 4 feet of cable passes over the roof and if the cable terminates at a through-the-roof raceway or support. This is similar to clearances allowed for service drop wires.

11. Provide at least 3 feet vertical clearance between broadband cables and roofs with a slope of at least 4 inches in 12 inches.

2. Connect the grounding/bonding wire to the broadband cable shield at a point as close as possible to where the outside cable terminates outside the building. If the outside cable enters the building, make this connection at a point as close as possible to where the outside cable enters the building.

3. Run the grounding/bonding wire in as straight a line and as short a distance as possible from the broadband cable shield grounding/bonding connection point to an approved grounding/bonding point.

4. Limit the length of the grounding/bonding wire to not more than 20 feet. If the broadband cable shield ground/bonding point is more than 20 feet from an approved grounding point, you may install at least an 8-foot-long ground rod near where the cable enters the building and bond the ground rod to the electrical service grounding system using at least #6 AWG copper wire.

5. Connect the grounding/bonding wire(s) to one of the following approved grounding/bonding points in other than manufactured homes: (a) the intersystem bonding connection terminal; (b) the building’s grounding electrode, grounding electrode wire, or other metal part of the building grounding electrode system; (c) a metal water service pipe not more than 5 feet from where the water service pipe enters the building; (d) the service equipment cabinet or non-flexible metal service equipment raceway; or (e) the other system grounding/bonding connection described in the IRC.

6. Connect the grounding/bonding wire(s) to one of the approved grounding/bonding points described above at manufactured homes if the home has service equipment or a grounded power disconnecting means located not more than 9 feet from the nearest wall of the home.

7. Connect the grounding/bonding wire(s) to the manufactured home’s grounding electrode if the home does not have service equipment or a grounded power disconnecting means located not more than 9 feet from the nearest wall of the home. Use at least #6 AWG copper wire to make this connection.

8. Connect the broadband cable shield to the metal frame of the manufactured home if the grounding/bonding connection is made as described in #7 above. Use at least #12 AWG copper wire to make this connection.

9. Protect the grounding/bonding wire if it is exposed to physical damage. Use a wiring method, such as metallic conduit, that is approved for use in physical damage environments.

2. You may install low-power and medium-power broadband cables and electric power wires in the same cabinet or box when the electric power wires are intended to supply power to the broadband cable system, such as for an amplifier.

3. Separate indoor broadband cables and electric power wires by at least 2 inches.

4. Separation described in number 3 is not required if the electric power wires or broadband cables are enclosed in conduit, tubing, metal cable armor or if the electric power wires and cables are permanently separated from each other by a continuous non-conductive material.

5. Separation described in number 3 is not required if the electric power wires are contained in a jacket, such as with types NM, UF, and AC cable. This means that, in most cases, separation between broadband cables and electric power wires is required only when individual electric wires are installed in conduit or tubing.

6. Provide, if possible, at least 6 feet of separation between coaxial cables and any part of a lightning protection system.