GENERAL BUILDING/ STRUCTURE

Accessibility

1. Provide disability accessibility features as required by the International Building Code for Group R-3 occupancy when at least () 4 dwelling or sleeping units are located in one building. This means that one and two-family homes and townhomes with fewer than (<) four units in one building need not have disability accessibility features.

Asphalt (Fiberglass) Shingle Roof Covering Materials

Shingle Roof Covering Description

Shingle roof covering materials discussed in this section are the fiberglass strip shingles used in modern residential construction. Strip shingles are the most common roof covering material in modern residential construction. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of
horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run. Read the full Topic

Attic Access

Attic Access Requirements

1. Provide an access opening to every attic with at least () 30 square feet of attic area and a vertical height of at least () 30 inches at some point in the 30 square feet. Measure the vertical height from the top of the ceiling joists (or truss bottom chord) to the bottom of the rafters (or truss top chord). Read the full Topic

Attic Ventilation

Attic Ventilation Requirements

1. Provide ventilation to attic spaces, unless you design and build the attic as an unventilated, conditioned attic assembly. Provide ventilation when ceilings are applied directly to roof rafters, such as cathedral and vaulted ceilings, and in attics over unconditioned spaces, such as garage attics. Provide ventilation to each individual attic and ceiling space, unless there is eff ective means for air to move between spaces. The building official may waive att ic ventilation requirements. Read the full Topic

Backflow Protection by Air Gaps

Air Gap Required Locations
1. Use clothes washing and dish-washing machines that contain an air gap device in the machine.
2. Provide an air gap at the discharge point of any relief valve and any relief valve piping (such as a water heater temperature and pressure relief valve discharge pipe).

Read the full Topic

Backflow Protection of Water Supply

Backflow and Cross-Connections Discussion
An important part of the design and use of the drinking (potable) water supply system is preventing contamination of potable water. Contamination can occur when the potable water supply is intentionally or unintentionally connected to a contaminant source. A cross-connection is a connection between the potable water supply and a potential contaminant source. Backflow is when material (usually liquid) travels in the reverse of the intended direction within a cross-connection. Contamination occurs when contaminated material backfl ows into the potable water system through a cross-connection. Some cross-connections are intended. Examples of intended cross-connections include toilet tank fill valves, automatic fill systems for swimming pools, and lawn irrigation systems.

Read the full Topic

Backflow Protection Using Backflow Prevention Devices

Backflow Protection Device General Installation Requirements
1. Protect all drinking (potable) water supply openings, outlets, and connections by an air gap or by an approved backfl ow preventer. This means that any place from which water flows must have either an air gap or have a backfl ow preventer installed. Examples of openings, outlets and connections include sinks, bathtubs, showers, hose bibbs, and water supply connections to water and steam heating systems, irrigation systems, swimming pools, fountains, ponds, and similar water features.
Read the full Topic

Bathroom Light and Ventilation

Bathroom Light and Ventilation

1. Provide outdoor light and ventilation to bathrooms, toilet rooms, and similar areas using windows or doors containing glazing. Provide a total glazing area of at least () 3 square feet

with atleast () 1 ½ square feet operable. Open the glazing directly on to a street, public alley, or on to a yard or court located on the same lot. Read the full Topic

BUILDING PERMITS (R105)

Local Regulations and Customs for Building Permits

  1. Contact the building official to determine which construction activities require a building permit and to determine the documents and procedures required to obtain a permit. The building official may not enforce some building permit requirements contained in the IRC and may add additional building permit requirements not contained in the IRC. Read the full Topic

Buildings Governed by the IRC (International Residential Code)

Apply the IRC to townhouses.

A townhouse contains at least (≥) 3 individual dwelling units in one building. See Chapter 2 for a definition and an illustration of a townhouse. Read the full Topic

Ceiling Joist and and Rafter Framing Details

Ridge, Valley, and Hip Rafter Framing

1. Install at least () a 1 inch (nominal thickness) ridge board at roof ridges. Install a ridge board that is at least () as deep as the (plumb) cut end of the rafter. Install rafters directly across from each other at the ridge board. You may omit the ridge board if you secure the rafters to each other with a gusset plate. Read the full Topic

Ceiling Joist and Rafter Boring and Notching

 Ceiling Joist and Rafter Notching

1. Notch structural dimension lumber ceiling joists, rafters, blocking, and beams not deeper than () one-sixth of the actual depth of the member. Notch the member not longer than () one-third of the actual depth of the member. Do not place any notches in the middle one-third of the member. Example: notch a 2×8 ceiling joist not more than () 1 ¼ inches deep and not more than () 2 ½ inches long.

Read the full Topic

Ceiling Joist and Rafter Openings

Joist and Rafter Openings Description

Common reasons for openings in ceiling joists and rafters include openings for attic access (scuttleholes and pull-down stairs), openings for whole house fans and skylights, and framing for dormers or similar structures. The header joists distribute the load of the tail joists to the trimmer joists. Read the full Topic

Ceiling Joist and Rafter Spans

An attic with limited storage is designed with an additional 10 pounds per square foot live load compared to an attic without storage. Verify the storage capacity of truss-built attics with the truss engineer before using the attic for storage.

Read the full Topic

Certificate of Occupancy

Certificate of Occupancy Required

1. Do not move into or occupy a building until after the building official issues a certificate of occupancy. Read the full Topic

Concrete and Clay Tile Roof Covering Materials and Installation

Tile Roof Covering Description
Roof tiles are made using concrete or clay and come in several shapes. The most common shapes are flat and an S shape. Clay tiles are very delicate and are easily broken. Concrete tiles are more durable. Avoid walking on tile roof unless you are trained how to do so. Concrete and clay tiles are among the most expensive roof covering materials and usually have a long useful life.The underlayment material and the flashing are the waterproof membrane that seals the home from water penetration. The tile serves only to protect the underlayment from exposure to sunlight and excessive moisture and to look good. The provisions for tile application in this section are general and primarily for moderate climates. Refer to tile manufacturer’s installation instructions and local installation requirements for your area. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Roof Slope Restriction
1. Do not install tiles on roofs with a slope less than (<) 2 ½ /12.
2. Install a double underlayment layer under tiles on roofs with a slope between 2 ½ /12 and 4/12.

Roof Deck Type Restriction
1. Install tile roof covering on solid sheathed roofs or on spaced structural sheathing.

Underlayment Specifications
1. Use at least (≥) 30 pound (per 100 square feet) roofing felt. This is the most common tile roof underlayment. Other materials, such as mineral surfaced roll roofing, are often superior to roofing felt. Refer to the IRC for other acceptable underlayment for tile roofs.
2. Refer to the IRC for additional requirements in wind speed areas of 120 mph or more.

Underlayment Application for Roof Slopes 4/12 and Greater
1. Begin at the eaves and apply at least (≥) a 36 inches wide strip of underlayment parallel to the eaves.
2. Lap horizontal joints at least (≥) 2 inches with the upper strip over the lower strip.
3. Lap end joints at least (≥) 6 inches.
4. Lap underlayment at least (≥) 1 inch over rake edges. (industry recommendation).
5. Use suffi cient fasteners to hold underlayment in place. The IRC does not specify fastener type and quantity.

Underlayment Application for Roof Slopes Between 2 ½ /12 and 4/12
1. Begin at the eaves and apply at least (≥) a 19 inches wide strip of underlayment parallel to the eaves.
2. Begin again at the eaves and apply at least (≥) a 36 inches wide strip of underlayment.
3. Lap each successive layer at least (≥) 19 inches over the previous layer with the upper layer over the lower layer.
4. Lap end joints at least (≥) 6 inches.
5. Lap underlayment at least (≥) 1 inch over rake edges. (industry recommendation).
6. Use suffi cient fasteners to hold underlayment in place. The IRC does not specify fastener type and quantity.
7. Refer to the illustration in Section R905.2.

Underlayment Application in 110+ mph Wind Areas
1. Apply underlayment according to the roof slope.
2. Install corrosion-resistant fasteners according to manufacturer’s instructions and space them along the overlaps at not more than (≤) 36 inches.

Batten Installation (Industry Recommendation)
1. You are not required to use batt ens when installing a tile roof, unless recommended by the manufacturer. If you use batt ens, follow these industry installation recommendations.
2. Install batt ens that are at least (≥) 1×2 utility grade wood, not longer than (≤) 4 feet, and installed with at least (≥) a ½ inch gap between each batt en for drainage. Alternative installations that allow drainage under or between batt ens are acceptable.
3. Space batt ens based on the size and type of tile and on the tile manufacturer’s recommendations.
4. Att ach batt ens using at least (≥) 8d corrosion-resistant nails spaced not more than (≤) 24 inches on center and long enough to penetrate at least (≥) ¾ inch into or through the sheathing. Alternative fasteners are corrosion-resistant staples at least (≥) 16 gage, 7/16 inch crown, 1 ½ inches long, and long enough to penetrate at least (≥) ¾ inch into the sheathing, and spaced not more than (≤) 12 inches on center.

Valley Flashing
1. Install at least (≥) a 22 inches wide strip of metal with at least (≥) 11 inches on each side of the valley. Use metal valley flashing with at least (≥) a 1 inch high splash diverter rib running down the valley center. The metal should be at least (≥) 0.019 inch thick galvanized steel or equivalent corrosion-resistant metal. Metal fl ashing sections should end lap at least (≥) 4 inches with the upper section over the lower section.                                                                                                                                                                                                          2. Install at least (≥) a 36 inches wide roll of ASTM D 2626 Type I roll roofing under the metal valley material, if the roof slope is at least (≥) 3/12.
3. Apply adhesive between the Type I roll roofing and the underlayment or install a self-adhering polymer modified bitumen sheet instead of the Type I roll roofing where the average daily January temperature is 25º F or less.

Sidewall and Penetration Flashing
1. Install roof penetration flashing, such as plumbing vent flashing, according to the flashing manufacturer’s instructions. Install roof and sidewall intersection flashing using base flashing and counter flashing installed according to manufacturer’s instructions.

Fastener Type
1. Install corrosion-resistant nails with at least (≥) an 11 gage shank and a 5/16 inch diameter head. The nails should be long enough to penetrate into the roof sheathing at least (≥) ¾ inch and completely through any sheathing that is less than (<) ¾ inch thick.

Perimeter Tile Nailing
1. The roof perimeter includes both sides of hips and ridges, gable rake edges, and eave edges.
2. Install at least (≥) one nail per tile within at least (≥) 3 tile courses of the perimeter and at least (≥) 36 inches from the perimeter edge, whichever is greater.

 

Field Tile Nailing in Standard Conditions
1. Field tiles are all tiles other than perimeter tiles and cap tiles on ridges and hips. Standard conditions are design wind speed of not more than (≤) 100 mph, and buildings with a roof 40 feet or less above the ground, and areas not subject to snow.
2. Install at least (≥) one nail per field tile when tiles cover solid roof sheathing and no battens are installed.
3. You are not required to install nails in field tiles when battens are installed and the roof slope is less than (<) 5/12.
4. Install at least (≥) one nail per tile when tiles weigh less than 9 pounds per square foot.
5. Install two nails per tile in areas subject to snow.

Field Tile Nailing in Special Conditions
1. You may be required to install nails in most or all tiles if the roof slope exceeds (>) 5/12, or if the design wind speed exceeds (>) 100 mph, or if the roof is higher than (>) 40 feet above the ground, or if the roof is subject to snow. Verify fastening requirements with the tile manufacturer and the local building official if any of these special conditions exist.

Tile Roof Covering Best Practice
Tile is usually a very heavy roof covering material. Verify that the rafters or trusses are designed and braced to carry the load. Do not install tile on a roof that was previously covered by another roof covering material without evaluation of the roof framing and support by a qualifi ed engineer or contractor. A good quality concrete tile roof can have a useful life exceeding 80 years. Thirty pound felt underlayment can start to deteriorate in as few as 10 years and may need replacement before the end of the tile’s useful life. Consider installing mineral-surfaced roll roofi ng as tile underlayment instead of thirty pound felt. Good quality underlayment and fl ashing materials should perform well for the entire life of the tile roof.

 

 

 

 

Concrete Slab-On-Grade Floors

Concrete Thickness and Strength

1. Make concrete slab-on-grade floors at least () 3 ½ inches thick. This does not include extra thickness for footings and interior bearing walls. Read the full Topic

Concrete Strength

Concrete in Foundation Walls and Footings Not Exposed to Weather

1. Use at least () 2,500 psi concrete in all weathering potential environments. Read the full Topic

Crawl Spaces

Crawl Space Ventilated to Exterior

1. Provide at least () one square foot of net free ventilation area for every 150 square feet of crawl space floor in a ventilated crawl space. You may reduce the net free ventilation area to at least () one square foot for every 1,500 square feet of crawl space floor if you cover the floor with a vapor retarder such as 6-mil polyethylene. Read the full Topic

Cripple Walls

Cripple Wall Definition Read the full Topic

Decks

Deck Attachment to the Building General Requirements

1. Design decks to resist both vertical and horizontal (lateral) loads where the deck is attached to the building. Read the full Topic

Deflection (Bending) of Structural Components

Limitations of the Material in this Section

Most readers should not deal with bending of structural components such as floors, walls, ceilings, and roofs. Leave this to qualified engineers and contractors. Because “spongy” floors and rattling walls are common complaints, this section explains some basic concepts involved in deflection and helps you understand when deflection may be excessive.

Read the full Topic

Draftstopping

Draftstopping

Draftstopping helps limit the movement of air in floor framing and in floor/ceiling assemblies. Draftstopping may also be used as part of a fire separation measure in the

attic of a two-family dwelling. Draftstopping is most often required when using open web (metal plateconnected) floor trusses and when a ceiling is suspended under a floor. Do

not confuse draftstopping with fireblocking. Fireblocking occurs in wall assemblies. Read the full Topic

Drywall (Gypsum Board) Interior Application

Limitations of the Material in this Section

The IRC Section and the Gypsum Association publication GA-216-04 present the methods for applying different thicknesses of drywall (gypsum board) to interior supports such as wood framing, metal framing, and masonry. The material in this section presents the more common methods of attaching drywall to wood framing Read the full Topic

Emergency Escape Openings

Escape Opening Locations and General Requirements

1. Provide at least () one escape opening in every bedroom including bedrooms above, at, and below ground level. This escape opening is not required if the building is

equipped with an automatic fire sprinkler system. Read the full Topic

Exterior Doors

Egress Door Definition

Egress door: The egress door is a door to the outside that meets all egress door requirements. 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. Read the full Topic

Exterior Surface Drainage and Gutters

Drainage Near Home

1. Direct surface water away from the foundation to a storm sewer or other approved collection point. Read the full Topic

Exterior Wall Coverings

 

Water-Resistive Barrier General Installation Requirements

1. Install at least () 1 layer of No. 15 asphalt felt over all exterior stud walls and wood sheathed walls, unless an exception applies. You may use other approved water-resistive materials, such as some house wraps and Grade D paper, instead of felt. Read the full Topic

Fire Seperation Between Buildings

Fire Separation Distance Definition

Fire separation distance: The fire separation distance is the horizontal distance between the

home’s exterior wall (the face of the building) and a fire separation line. The fire separation distance

is measured between the fire separation line and the exterior wall at a right angle to the

exterior wall. The fire separation line is usually the property line between lots. In urban settings

where buildings are close together and close to streets and sidewalks, the fire separation distance

may also be measured to the center line of a street, alley, or public sidewalk as determined by the

local building official. For two-family dwellings and townhouses, the fire separation line is an

imaginary line between dwellings. When two or more dwellings are attached, the fire separation

distance is zero. Read the full Topic

Fire Sprinkler System

1. Install an approved automatic fire sprinkler system in new one and two-family homes according to NFPA 13D or IRC Section P2904. Note that adoption of this provision may vary by jurisdiction. Verify local adoption with the local building official. Read the full Topic

Fire Sprinkler System General Requirements

Limitations of the Material in this Section
The IRC provides detailed requirements for designing and installing residential fire sprinkler systems. Readers of this book should not att empt to design or install these systems. Consult qualified sprinkler system contractors when dealing with these systems. In this book section we present some general installation requirements to help readers bett er understand the nature and scope of residential fire sprinkler systems. Note that this requirement is very controversial and many jurisdictions do not require these systems. Verify with the local building offi cial if fi re sprinkler systems are required in your area.

Read the full Topic

Fireblocking

Fireblocking:  Fireblocking (also called firestopping) limits the spread of fires vertically between

stories in concealed wood-framed walls and horizontally in long concealed areas such as double

walls, framed openings, and drop soffits above cabinets. Concealed vertical spaces in woodf ramed

walls can act like a chimney providing fire an easy and rapid path between stories. Lack

of fireblocking increases the chance of property damage and loss of life during a fire.

Do not confuse fireblocking with draftstopping. Draftstopping limits the horizontal movement of

air in concealed areas such as floor/ceiling assemblies. Read the full Topic

Fixture Traps

Trap Size
1. Use the following table to determine the minimum trap size for most plumbing fixtures.
2. Do not install separate traps on toilets, urinals, and other fi xtures 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 1 ½ inch pipe on the discharge side of the trap.

Trap Design
1. Install traps of standard design that: (a) have a smooth internal surface for water flow, and (b) are self-cleaning, and (c) do not have interior partitions or moving parts, and (d) are constructed using cast iron, cast or drawn brass, or approved plastic. Standard design for modern fixture traps is the P trap. Read the full Topic

Fixture Traps

Trap Size
1. Use the following table to determine the minimum trap size for most plumbing fi xtures.
2. Do not install separate traps on toilets, urinals, and other fi xtures that have traps in the fi xture 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 1 ½ inch pipe on the discharge side of the trap. Read the full Topic

Flood Resistant Construction

1. Use flood-resistant construction in designated flood hazard areas. Verify with the local building official if the area is in a flood hazard area. Flood-resistant construction involves elevating the lowest floor level of the structure above the flood level, installing mechanical, electrical, and plumbing components above the flood level, and reinforcing the foundation to withstand forces from water and wave action. Refer to the IRC for more information about flood-resistant construction requirements.

Floor Joist Openings

Floor Joist Openings Description

Framed openings in floor joists are mostly used for stairways between floors and for chimneys. The header joists distribute the load of the tail joists to the trimmer joists.

Read the full Topic

Floor System Fire Protection

Fire Protection of Floor Framing

1. Install at least () ½ in. thick gypsum drywall, thick wood structural panel, or equivalent material on the under side of I-joist type floor joists, metal plate connected floor trusses, and dimension lumber joists smaller than (<) 2X10 unless an exception applies. This provision does not apply if the floor system is required to be fi re-resistant by another code provision.  Read the full Topic

Foam Plastic Insulation and Trim

Foam Plastic Products Definition

Foam plastic: Foam plastic products addressed in this section include: (a) extruded polystyrene sheet insulation from manufacturers such as Dow® and Owens Corning®, and (b) spray-applied polyisocyanurate foam products such as Great Stuff ® and spray-applied foam insulation that is now available for insulating wall cavities and for insulating around rafters in semi-conditioned attics, and (c) flexible interior trim moldings such as crown and base moldings. Read the full Topic

Footings

Soil Load Bearing Capacities

1. Place footings on undisturbed soil of known bearing capacity or on fill approved by an engineer. Read the full Topic

Foundation and Retaining Walls

Limitations of the Material in this Section

The IRC provides complex rules governing the design of and the lateral support of foundation walls. We do not recommend that readers of this book attempt to design or build foundation walls. Consult a qualified contractor or engineer regarding foundation walls. Refer to the IRC Commentary for more information about foundation wall construction. Read the full Topic

Foundation Drains and Dampproofing

Dampproofing and Waterproofing Definitions

Dampproofing: Dampproofing inhibits the flow of water vapor and small quantities of liquid water under slight pressure through a foundation wall.

Waterproofing: Waterproofing inhibits the flow of water vapor and larger quantities of liquid water under higher pressure through a foundation wall. Read the full Topic

Glass Block Walls

Glass Block Size

1. Use standard size hollow or standard size solid glass blocks that are at least () 3 inches thick. Read the full Topic

Guards

Guards Definition

Guard: A guard is a barrier that protects occupants from falling from a raised surface such as a stairway, deck, or balcony. Guards are often call guardrails when the guard also

serves as a handrail; however, guards need not be an open rail. A guard may be a partial height solid wall, a partial height wall containing safety glazing, or any other structure that

complies with IRC requirements. Read the full Topic

Gutters

When Gutters are Required

1. Provide gutters or other means to control roof runoff in areas with expansive or collapsible soil. Discharge the gutter water at least () 5 feet away from the foundation or into an approved drainage system. Read the full Topic

Habitable Rooms and Ventilation

Habitable Rooms Definition

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 special size, ceiling height, heating, lighting, and ventilation, requirements. Rooms that are not considered habitable do not have those requirements. Habitable Rooms Light and Ventilation

Read the full Topic

Hallways

Hallway Dimensions

1. Build each hallway with a minimum finished width of at least () 36 inches. Read the full Topic

Handrails

Location

1. Provide a handrail on at least () one side of every continuous flight of stairs with four or more risers.

Height Read the full Topic

Headers

1. Refer to Section R502.5 in this book for information about allowed header spans in exterior and interior load-bearing walls. Read the full Topic

Inspection

Inspection General Requirements

  1. Contact the building official to determine the required inspections for a construction project.
    Each jurisdiction has its own rules for inspections. These rules include: which inspections it performs,
    what work must be complete before requesting the inspection, how and when to schedule
    the inspection, and how it handles inspections of work that fails inspection. The following descriptions
    list the work that is often completed before scheduling the inspection. Read the full Topic

Insulation Clearance to Heat Producing Devices

Insulation Clearance Requirements

1. Provide at least () 3 inches clearance between combustible insulation and heat-producing devices such as recessed lighting fixtures and fan motors. Most insulation used in modern homes is considered combustible.

Read the full Topic

Low Slope (Flat) Roof Covering Materials and Installation

Low Slope Roof Covering Description                                                                                                                                 

Roofs that are often described as “flat” are not supposed to be flat. They must be sloped to drain water toward scuppers or roof drains. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Read the full Topic

Manufactured Wood Floor Trusses and Joists

Wood I-Beam Floor Joists Notching and Boring

1. Notch, bore, splice or alter wood I-Beam (TJI-type) floor joists only as specified by the manufacturer’s instructions. Altering the top and bottom flange is usually not allowed. Hole boring is usually allowed in the middle third of the span and is restricted near the joist ends.

Read the full Topic

Manufacturer’s Instructions

Manufacturer’s Instructions Discussion

Manufacturer’s instructions are an important part of the IRC. They are referenced many times in the IRC and in the Commentary. Read the full Topic

Masonry

Isolated Masonry Piers

1. You may use hollow core concrete masonry units (concrete blocks) to build isolated masonry piers if the units are at least () 8 inches thick and not longer than () 3 times the unit thickness. An isolated masonry pier may not support a floor girder or beam. Read the full Topic

Masonry (brick) and Stone Veneer

Water-Resistive Barrier General Installation Requirements

1. Install a water-resistive barrier over all sheathing covered by masonry and stone veneer. This includes wood-based sheathing and foam plastic sheathing.

Read the full Topic

Masonry Walls Above Grade

Limitations of the Material in this Section

These IRC sections present requirements for building above-grade walls using several types of masonry units. These sections also present requirements for anchoring joists and rafters to masonry walls. You may build masonry walls using single wythe (layer) or multiple wythe masonry units. Note that these IRC sections do not apply to basement, crawl space, or other foundation walls. The most common masonry unit for building residential walls is the concrete masonry unit (CMU), also known as a concrete block or cinder block. Read the full Topic

Metal Panel Roof Covering Materials and Installation

Metal Panel Roof Covering description

Metal panel roof coverings have an exposure of at least 3 square feet per panel. This distinguishes metal panels from metal shingles. Metal panels may be fl at lapped panels that are either unsealed at the laps or are sealed or soldered at the laps. Metal panels may also be a standing seam type where the seams between panels are raised above the roof surface. Standing seam metal roof coverings are a good selection in high wind areas because they resist being blown off by high winds. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Read the full Topic

Metal Shingle Roof Covering Materials and Installation

Metal Shingle Roof Covering Description

Metal shingles have a weather exposure area of less than (<) 3 square feet per shingle. This distinguishes them from metal panel roof coverings that have a larger weather exposure area. Metal shingles must be made from naturally corrosion resistant metal or from metals treated with a corrosion resistant coating. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Read the full Topic

Mineral-Surfaced Roll Roof Covering Material

Mineral-Surfaced Roll Roof Covering Description

Mineral-surfaced roll roofi ng material usually comes in 36 inch wide rolls. It is usually a lower quality and less expensive roof covering material compared to other roof covering materials. It is commonly used on temporary buildings, accessory buildings, low slope porch roofs, and in other applications where long life is not critical. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

Read the full Topic

Outdoor Air Intake Openings

Outdoor Air Intake Openings

1. Provide at least () 10 feet horizontal separation between all mechanical and gravity outdoor air intake openings and gas and oil vents, chimneys, plumbing vents, streets,

alleys, and similar contaminant sources. Gravity outdoor air intake openings include: (a) openings for makeup air and combustion air, and (b) attic eave vents, and (c) windows,

doors, and similar openings. Mechanical outdoor air intake openings include air intakes connected to furnaces and air handlers and powered air exchange ventilation systems. Read the full Topic

Penetrations in Fire-Resistive Walls and Ceilings

Summary of Penetration Requirements

1. Refer to the IRC Commentary for more information about fire-resistive wall and ceiling penetration requirements and exceptions. Most readers of this should not deal with this

complex subject. The following is a summary of the basic provisions. Read the full Topic

Plumbing Fixture Minimum Clearances and Requirements

Required Plumbing Fixtures

1. Provide every home with at least () one toilet, and one bathroom sink, and one tub or shower, and one kitchen sink.

Read the full Topic

Repair and Replacement of Roof Coverings

Definition of Repair versus Replacement of  Roof Coverings                                                                                                                                                                                                                        

1. You may repair existing roof covering material using the same materials and methods used on the existing roof, if you repair less than (<) 25 percent of the roof area in a 12 month period.
2. Comply with IRC provisions for new roof covering material, if you repair more than (≥) 25 percent of the roof in a 12 month period.
3. Refer to the International Building Code for additional information.

Read the full Topic

Repairs and Alteration to Existing Buildings

1. You are not required to update existing buildings to current code requirements if: (a) the building and systems were lawfully in existence when the local jurisdiction adopted the code, and if (b) the building and systems are safe as determined by the building official. There are exceptions to this general rule. See smoke alarms.

2. Apply current code requirements when adding to or altering a building and its systems. This means that if you perform work requiring a permit, the permitted work must comply with current code. You are not required to update the existing work to current code requirements. This provision applies regardless of whether or not you actually obtain a permit.

Reverse Osmosis Water Treatement Units

Air Gap for Waste Discharge
1. Install an air gap or a backflow prevention device between the reverse osmosis waste or discharge line and the connection to the plumbing waste pipe. The reverse osmosis unit manufacturer should provide an air gap faucet or a backfl ow prevention device to comply with this provision. The faucet or device should be labeled as meeting the requirements of NSF 58.

Roof Flashing and Drainage

 Roof Flashing Locations and Materials

1. Install flashing:

(a) at all intersections between roofs and sidewalls, and

(b) at all points where a roof changes direction or pitch, and

(c) at all intersections between parapet walls and roofs, and Read the full Topic

Roof Uplift Resistance

1. Attach trusses and rafters to the supporting walls using either 3-16d box nails (3½ in. x 0.135 in.) or 3-10d common nails (3” x 0.148 in.). Toe nail the trusses and rafters to the top plate placing two nails on one side and one nail on the other. This applies when: (a) roof uplift force is not more than () 200 pounds and the trusses and rafters are spaced not more than () 24 inches on center; Read the full Topic

Room Size and Ceiling Height Requirements

Habitable Rooms Dimensions

1. Provide every home with at least () one habitable room that has an area of at least () 120 square feet. Read the full Topic

Safety Glazing

Safety Glazing Labeling

1. Label every pane of glazing in a hazardous location with a permanent marking that identifies the type of glazing (usually tempered) and the safety glazing standard with which it

complies. This includes inside, outside, and any middle panes in a multiple-pane window or door. The glazing manufacturer usually etches this label into a corner of the glazing. See #2

below for the safety glazing standards that should appear on the label. Read the full Topic

Seismic and Wind Design Areas

Seismic Design Areas

1. Provide increased strength and structural integrity for foundations, walls, roofs, gas pipes and appliances, and other components in seismic design areas. Refer to the IRC and consult a qualified engineer or other qualified professional when building in seismic design areas.

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Sile, Sole, and Top Plates

Top Plate Construction

1. Use at least () two 2 inch (nominal) depth top plates that are at least () as wide as the studs at the top of load-bearing walls. Example: use two 2×4 top plates on top of a 2×4 wall. 2. Off set 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. Read the full Topic

Site Address

1. Install approved building address numbers or letters that are clearly legible from the road fronting the property. This is so emergency responders can quickly locate the property. Make the letters or numbers Arabic type that are at least () 4 inches tall and at least () ½ inch wide. Make the letters and/or numbers contrast with the background.

Skylights and Sloped Glazing

Sloped Glazing Definition

Sloped glazing, including skylights, is any glazing material installed with a slope of at least () 15 degrees from vertical. The glazing may be on a roof or in a wall. If the glazing slopes at least () 15 degrees from vertical, it is sloped glazing.

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Slate and Slate Type Shingle Roof Covering Materials

Slate and Slate Type Shingle Roof Covering Description

Slate is a natural stone material. Artifi cial slate is also available. Natural slate is very heavy and requires roof framing designed to carry the load. Natural slate has a very long useful life. When high quality natural slate is properly maintained, it can last as long as the home. Natural slate is not commonly used in modern residential construction. Install slate shingles according to the shingle manufacturer’s installation instructions. If the manufacturer does not publish installation instructions, the National Roofing Contractors Association publishes authoritative information about proper installation and fl ashing for most common roof covering materials.
Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run. Any reference to slate shingles includes artificial slate type shingles.

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Smoke and Carbon Monoxide Alarms

Smoke Alarm Required Locations

1. Locate a smoke alarm: (a) in every bedroom, and (b) outside all bedroom areas in the immediate vicinity (usually about 10 feet) of all bedrooms, and (c) on every level in the home,

including basements and habitable attics. Read the full Topic

Stairway Lighting

Interior Stairway Light Locations

1. Locate a light fixture near each stairway landing, including the top, bottom, and any intermediate landings. You may locate a light fixture directly over each stairway section instead of near each landing. The light must be capable of illuminating treads and landings of interior stairs to at least () 1 foot-candle.

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Stairways

Stairway Definitions

Landing: A landing is a flat surface at the top and bottom of a stairway. Landings may also occur at points within a stairway. A landing must be at least () as wide as the stairway and at least () 36 inches deep.

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Stucco Application

Limitations of the Material in this Section

Traditional three-coat cement plaster (stucco) is less frequently used in many parts of the country because of the lower cost of newer synthetic stucco materials. As such, we will not deal with the rules for mixing and applying cement plaster. The material in this section addresses issues common to synthetic and traditional stucco. Read the full Topic

Sump Pits and Pumps

Sump Pit and Sump Pump Requirements
1. Install a sump pump that has the capacity to discharge storm water at the anticipated flow rate and to move water up any required vertical distance.
2. Install a sump pit that is at least (≥) 18 inches wide and 24 inches tall, unless the building official approves a different size.
3. Construct the sump pit using concrete, steel, or plastic with a solid bott om capable of supporting the pump.
4. Install an accessible full-fl ow check valve on the pump discharge pipe.
5. Install electrical circuits for the sump pump according to IRC requirements and the pump manufacturer’s instructions.
6. Install discharge pipes, including the underground drain pipes, that are at least (≥) as large as the pump discharge outlet.

Termite Protection

1. Provide protection against termite damage in areas subject to termites. These areas include almost all of the continental United States except areas in the far north. You may use any

approved protection method including: Read the full Topic

Townhouses

Townhouse Construction

1. Build townhouses as structurally independent buildings. The foundation and a 2 hour fire resistive common wall need not be structurally independent. Read the full Topic

Two Family Dwellings

Fire Separation of Two Dwelling Units in One Building

1. Separate two-family dwelling units that are built side-by-side in one building by building at least () a 1 hour fi re-resistive common wall between the dwellings. Build the common wall continuous between the foundation and the underside of the roof sheathing. Make the common wall tight against the foundation and the roof sheathing.

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Underground Storm Water Drains

Underground Drain Materials and Installation Requirements
1. Use at least a (≥) 4 inches diameter pipe of an approved type. The most common pipe materials for underground storm water drains are solid and perforated corrugated polyethylene and PVC drain pipe.
2. Install an accessible backwater valve if the storm water drainage system could allow water to flow into the building.
3. Discharge the water to an approved location above ground or into a sump pit, dry well, or a trapped area drain. Read the full Topic

Underground Storm Water Drains

Underground Drain Materials and Installation Requirements
1. Use at least a (≥) 4 inches diameter pipe of an approved type. The most common pipe materials for underground storm water drains are solid and perforated corrugated polyethylene and PVC drain pipe.
2. Install an accessible backwater valve if the storm water drainage system could allow water to flow into the building.
3. Discharge the water to an approved location above ground or into a sump pit, dry well, or a trapped area drain.

Wall Bracing

Limitations of the Material in this Section

The IRC presents many methods and complex rules for wall bracing. Wall bracing is best left to qualified engineers and architects. This section discusses a few common wall bracing methods and some general rules about how to install them. Read the full Topic

Wall Height and Stud Spacing

 Limitations of the Material in this Section

The IRC presents many combinations of wall heights, lumber sizes, and spacing. The discussion in this book section includes wall heights and stud spacing commonly used in new construction. Refer to the IRC for more information about other wall height and stud spacing combinations. Refer to the IRC for wall height and stud spacing requirements in high wind, heavy snow load, and seismic design areas. Read the full Topic

Wall Penetration Flashing

Flashing General Requirements

1. Use only corrosion-resistant flashing material such as aluminum, galvanized steel, and pealand-stick material. Corrosion resistance includes fasteners or other materials used to secure the flashing. Read the full Topic

Water Service and Distribution Pipe General Installation Requirments

Water Pipe Installed in Contaminated or Corrosive Ground
1. Do not install water service or distribution pipe, fittings, valves, or other parts in soil or water that is contaminated with materials that may corrode or degrade the pipe or materials. The building official may require a soil analysis or may require alternate pipe routes or pipe materials if contaminated or corrosive soils are found or suspected.

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Water Supply General Requirements

Drinking Water Required
1. Provide each dwelling with a supply of drinking (potable) water.
2. Identify any sources of non-potable water that may be supplied in a building. Use color, metal tags, or other approved means to identify both the potable and non-potable supply pipes and fixtures.

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Water Supply Pipe Size

Limitations of the Material in this Section
Determining the correct size of water pipes requires knowledge of the water pipe material(s) to be installed (e.g., copper or CPVC pipe), the length of each part of the water pipe system, the height of each fixture above the water source (e.g., water meter or well head), the water demand requirements of each fixture and fixture group, the water supply pressure, and the pressure loss induced by appliances such as water meters, backflow preventers, water softeners, and water filters. This knowledge is beyond most readers of this book; therefore, we will not discuss in detail how to determine water pipe sizes. Leave calculation of correct water pipe size calculations to qualified contractors. We will present some basic information about how to calculate water pipe sizes and present an example of calculating water pipe sizes for an average home. Read the full Topic

Water Supply Valves

Water Supply Service Cutoff Valve
1. Provide each dwelling (including each unit of a two-family and townhouse building) with a water supply cutoff valve near where the water supply pipe enters the dwelling. Use a full-open type valve such as a gate or ball valve. Make this valve accessible.
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Wood Floor Framing

Cantilever Definitions

Backspan: Backspan is the part of a cantilevered joist within the supporting wall.

Cantilever: A cantilever is an extension of a floor joist beyond a supporting wall or beam. The distance that one may cantilever a floor joist depends on the width of the

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Wood Floor Joist Boring and Notching

Boring and Notching Definitions

Bore: A bore is a hole drilled in a stud or joist. Use the actual dimensions to determine the depth of framing lumber and when calculating the maximum hole diameter.

Notch: 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 1 ½ inches by 5 ½ inches.

Example: the actual depths of a 2×8 and a 2×10 are about 7 ¼ and 9 ¼ inches.

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Wood Floor Joist Spans

Floor Joist Span Tables

1. Use 30 psf live load and 10 psf dead load for most joists under bedrooms and in attics with access by permanent stairs, in most cases. Permanent stairs do not include pull-down folding attic ladders. Read the full Topic

Wood Nailing Schedule

Limitations of the Material in this Section

The IRC describes many combinations of materials and fasteners used to attach wood structural members to other wood structural members. The discussion in this book section is limited to using nails to attach materials commonly used in new construction. Refer to the IRC for more information about other materials and fasteners. Read the full Topic

Wood on Concrete and Masonary, Wood in he Ground, Wood Exposed to the Weather

Treated and Decay Resistant Wood Definitions

Treated wood: Treated wood (also called pressure treated) is wood into which chemicals have been forced under pressure. The chemicals help the wood resist insects and decay. Note that the cut ends, holes, and notches in treated wood are not insect and decay resistant. Cuts, holes, and notches must be field treated to restore resistance. Note that smaller dimensions of treated wood (such as 2×4) may not be suitable for direct ground contact. Verify ground contact rating of treated wood with the wood supplier.

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Wood Shake Roof Covering Materials and Installation

Wood Shake Roof Covering Description

Wood shakes are usually sawn on one or two sides and do not have a uniform width and butt thickness. They may be tapered and may not have uniform surface. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run.

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Wood Shingle Roof Covering Materials and Installation

Wood Shingle Roof Covering Description

Wood shingles are usually sawn on all sides and have a uniform width and butt thickness. They are usually tapered with a relatively smooth and uniform surface. The butt end of a shingle is the thicker end of the shingle. Wood shingles are laid with the butt end toward the eaves. Roof slopes are shown as x/y where x is the number of vertical units rise and y is the number of horizontal units run. A 4/12 roof has 4 vertical units rise for every 12 horizontal units run. Application of the Material in this Section
Apply this section to wood shingles. Do not apply to wood shakes. Refer to R905.8 for wood shakes.

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Wood Structural Panel Sheating

Limitations of the Material in this Section

The IRC presents many combinations of materials and installation techniques for installing wood structural panels as sheathing on roofs and as subflooring and underlayment. This section includes common materials and installation techniques used in modern residential construction. Refer to the IRC for information about less common materials and installation techniques.  Read the full Topic

Wood Stud and Plate Boring Notching

Boring and Notching Definitions

Bore: A bore is a hole drilled in a stud or joist. Use the actual dimensions to determine the depth of framing lumber and when calculating the maximum hole diameter. Read the full Topic

Wood Truss and Installation and Bracing

Truss Design and Bracing Written Specifications Requirements

1. Use a qualified engineer to design all wood trusses such as roof and floor trusses. The engineer or truss manufacturer should provide written truss design and installation specifications and deliver them to the job site with the trusses. These specifications should include engineering information, such as chord live and dead loads, and assembly information, such as the size, species, and grade of each truss member, and installation instructions, such as where each truss should be located on the structure and how the trusses should be permanently braced. Read the full Topic