Free ICC B1 Exam Flashcards

The International Residential Code governs detached one- and two-family dwellings and townhouses not more than three stories above grade plane with a separate means of egress. Larger or commercial buildings fall under the IBC, not the IRC.

The building official is charged with administering, interpreting, and enforcing the code. They issue permits, conduct or oversee inspections, and may grant modifications, but they cannot waive code requirements without a documented basis such as an approved alternative.

A permit must be obtained before construction, enlargement, alteration, repair, or change of occupancy, with limited exemptions (such as small accessory structures and minor repairs). Work started without a required permit is subject to stop-work orders and penalties.

It is issued by the building official after final inspection confirms the work complies with the code and approved documents. A building may not be legally occupied for its intended use until the certificate is issued; occupancy before issuance is a violation.

Typical IRC inspection points occur in build order: footing/foundation, then under-slab/plumbing, then framing and rough mechanical/electrical/plumbing (before concealment), then insulation, then final. Concealing work before its required inspection is a common violation.

Habitable spaces, hallways, and portions of basements containing habitable space must have a ceiling height of at least 7 feet (84 inches). Bathrooms, toilet rooms, and laundry rooms may be 6 feet 8 inches minimum.

At least one habitable room (other than kitchens) must be not less than 120 square feet of gross floor area. Other habitable rooms must be at least 70 square feet, and no habitable room (except kitchens) may be less than 7 feet in any horizontal dimension.

Glazed (window) area must be not less than 8% of the floor area of the room served. This natural-light requirement may be omitted where artificial light providing the required average illumination is installed instead.

Openable area to the outdoors must be at least 4% of the floor area being ventilated. Mechanical ventilation supplying the required outdoor air rate may be provided instead of operable windows.

Bathrooms must have either an openable window of at least 1.5 square feet or a mechanical exhaust fan. Local exhaust must vent directly to the outdoors, not into an attic, crawl space, or other concealed area.

A water closet requires a clear space of at least 21 inches in front and a minimum of 15 inches measured from its centerline to any sidewall or obstruction (30 inches total clear width centered on the fixture).

Every sleeping room and every basement with habitable space must have at least one EERO opening directly to a public way, yard, or court. This is one of the most heavily tested life-safety items on B1.

5.7 square feet minimum. Exception: grade-floor or below-grade openings may be 5.0 square feet. "Net clear" means the actual open area when the sash is fully opened, not the rough or glazed dimension.

Minimum net clear opening height is 24 inches and minimum net clear opening width is 20 inches. Note: meeting both minimums alone does not satisfy the 5.7 sq ft area requirement (20 in x 24 in = only 3.3 sq ft).

The bottom of the clear opening may be not more than 44 inches above the finished floor. If the sill exceeds 44 inches (common in deep basements), a permanent step, platform, or window well ladder is required.

A window well must have a minimum horizontal area of 9 square feet with a minimum projection and width of 36 inches. Wells deeper than 44 inches require a permanently affixed ladder or steps usable with the window fully open.

At least one egress door must be side-hinged, providing a clear width of not less than 32 inches and a clear height of not less than 78 inches. The required egress door must not require a key, tool, or special knowledge to open from inside.

A landing or floor is required on each side of an egress door. The exterior landing may be up to 7.75 inches below the top of the threshold, provided the door does not swing over the landing.

7.75 inches maximum. Risers are measured vertically between leading edges of adjacent treads. The walking surface of treads and landings must be sloped no steeper than 1 unit vertical in 48 horizontal (2%).

10 inches minimum, measured horizontally between the vertical planes of the foremost projection of adjacent treads. Winder treads must be at least 10 inches at the walk line and never less than 6 inches at any point.

The greatest riser height (or tread depth) within a flight may not exceed the smallest by more than 0.375 inch (3/8 inch). Uniformity prevents trip hazards and is a frequently cited inspection defect.

6 feet 8 inches (80 inches) minimum, measured vertically from the sloped line connecting tread nosings to the ceiling or obstruction above. This applies along the full run and at landings.

Stairways must be not less than 36 inches in clear width above the permitted handrail height and below the required headroom. Handrails may project a maximum of 4.5 inches into that required width on each side.

Where solid risers are used and tread depth is less than 11 inches, a nosing of 0.75 inch to 1.25 inches is required. A nosing is not required where the tread depth is at least 11 inches.

Handrails are required on at least one side of any stairway with four or more risers. (Three or fewer risers do not require a handrail unless otherwise mandated by other provisions.)

Handrail top must be between 34 and 38 inches measured vertically from the sloped plane of the tread nosings. Continuity, graspability, and the 34-38 inch range are classic B1 test points.

A circular handrail must have an outside diameter of 1.25 to 2 inches. Non-circular Type I handrails must have a perimeter of 4 to 6.25 inches with a maximum cross-section of 2.25 inches.

Guards are required at open walking surfaces (including stairs, ramps, and landings) more than 30 inches above the floor or grade below. Required guard height is 36 inches minimum (stairs may use 34 inches at the open side).

Required guards must not have openings that allow passage of a 4-inch-diameter sphere. On the open side of stairs, the triangular area at the tread, riser, and guard bottom must reject a 6-inch sphere.

Footings must be sized to the IRC tables based on soil bearing and load; minimum concrete footing thickness is 6 inches, and footing projection beyond the foundation wall must be at least 2 inches but not more than the footing thickness.

Footings of buildings must extend below the frost line of the locality, or be frost-protected by an approved method. Exterior footings must also bear at least 12 inches below undisturbed ground surface where frost depth is shallow.

2,500 psi minimum at 28 days for basement walls, foundations, and other concrete not exposed to weather. Higher minimums (3,000-3,500 psi) apply to weather-exposed concrete in moderate and severe weathering regions.

Sill plates must be anchored with 0.5-inch-minimum-diameter anchor bolts (or approved straps) spaced not more than 6 feet on center, embedded at least 7 inches into concrete or grouted masonry.

Each plate section requires a minimum of two anchor bolts, with one bolt located between 4 inches and 12 inches from each end of the plate section. This end-distance rule is a common field defect.

Net ventilation opening must be at least 1 square foot per 150 square feet of under-floor area. This may be reduced to 1 per 1,500 sq ft if a Class I vapor retarder covers the ground (or in approved unvented crawl space designs).

Untreated wood framing must have at least 18 inches clearance to exposed ground, and untreated girders/beams at least 12 inches. Wood in contact with ground or concrete near grade must be naturally durable or pressure-preservative-treated.

Joists must bear at least 1.5 inches on wood or metal and at least 3 inches on masonry or concrete. Inadequate bearing is a frequently cited framing inspection defect.

Notches in the top or bottom must not exceed 1/6 of the joist depth, must not be in the middle third of the span, and end notches must not exceed 1/4 of the depth. Notches on the tension side of members 4 inches+ thick are prohibited.

Holes must not be larger than 1/3 the joist depth, must be at least 2 inches from the top or bottom edge, and at least 2 inches from any notch. Holes must not be located in the same cross-section as a notch.

Floor joists are limited to a live-load deflection of L/360 (span in inches divided by 360). This deflection ratio is the standard B1 reference for floor stiffness; ceilings with brittle finishes use L/240.

Bearing-wall studs may be notched up to 25% of width and bored up to 40% of width. Non-bearing partition studs may be notched 40% and bored up to 60% of the stud width.

The edge of a bored hole must be at least 5/8 inch from the edge of the stud. Where the hole or notch exceeds limits, the stud must be doubled with no more than two successive doubled studs bored.

Headers over openings in bearing walls must be sized per the IRC span tables and supported on jack (trimmer) studs sized to the opening width. Single members are not permitted where the table requires multiple plies.

Connections such as joist-to-sill, top plate laps, stud-to-plate, and sheathing nailing are governed by the IRC fastening schedule table. On the open-book exam, locating Table R602.3(1) quickly is more valuable than memorizing every value.

Rafters must bear at least 1.5 inches on wood/metal. Where rafters are not tied to ceiling joists or rafter ties, a structural ridge beam (not just a ridge board) is required to resist outward thrust at the walls.

Net free ventilating area must be at least 1 square foot per 150 square feet of attic space, reducible to 1 per 300 sq ft when 40-50% of venting is in the upper portion (with the balance at eaves) or a Class I/II vapor retarder is used.

An attic access opening is required where the attic area exceeds 30 square feet and has a vertical height of 30 inches or greater. The rough-framed opening must be at least 22 inches by 30 inches.

Fireblocking is required in concealed stud/joist spaces at floor and ceiling levels, at stair stringers (top and bottom), and around vent/pipe/duct openings to cut off concealed draft paths between stories and concealed spaces.

The garage must be separated from the residence by minimum 1/2-inch gypsum board on the garage side (5/8-inch Type X under habitable rooms). Doors between garage and residence must be solid wood 1.375 inches thick, solid/honeycomb steel, or 20-minute fire-rated; no opening directly into a sleeping room.

Smoke alarms are required in each sleeping room, outside each sleeping area, and on every story including basements, interconnected and hardwired with battery backup in new construction. CO alarms are required outside each separate sleeping area where fuel-fired appliances exist or an attached garage is present.