Residential Building Inspector B1 flashcards

The IRC specifies a minimum thickness for concrete slabs-on-ground, particularly for habitable spaces, to ensure structural integrity.

• Minimum 3.5 inches (89 mm) for habitable spaces.
• Minimum 4 inches (102 mm) for garage slabs.
• Must be placed over a vapor retarder when required.

Memory trick: Habitable's half-inch more than three.

The maximum distance a floor joist can safely extend between supports without excessive deflection or failure, determined by material, size, spacing, and applied loads.

• Span limits are found in IRC tables.
• Factors include joist species/grade, dimensions, spacing, and live/dead loads.
• Exceeding span limits leads to structural failure or excessive deflection.

Memory trick: Joist Spans Require Careful Table Lookups.

A thin layer of material installed over the subfloor to provide a smooth, stable, and uniform surface for the finish flooring.

• Essential for resilient flooring (vinyl, linoleum) to prevent telegraphing.
• Helps absorb minor subfloor imperfections.
• Typically plywood, hardboard, or cement board.

Memory trick: Subfloor, Underlayment, Finish: S-U-F.

The method of applying construction adhesive between subfloor panels and floor joists to enhance structural integrity, reduce squeaks, and improve composite action.

• Required by IRC (R503.2.3) in addition to fasteners.
• Applied as a continuous bead on all supporting joists.
• Reduces squeaks by preventing movement between subfloor and joists.

Memory trick: Fasten Firmly, Adhere Actively, Resist Rattles.

The maximum on-center distance between supporting floor joists, dictated by the thickness and type of the subfloor material to prevent excessive deflection.

• Thicker subfloor allows wider joist spacing.
• Tongue-and-groove edges increase spanning capability.
• IRC tables specify maximum spacing based on subfloor type and thickness.

Memory trick: Subfloor Thickness Dictates Joist Spacing.

Diagonal or solid members installed between floor joists to provide lateral support, prevent twisting, and distribute concentrated loads.

• Enhances floor stiffness and stability.
• Prevents joists from buckling or rotating.
• Can be solid blocking or cross bridging.

Memory trick: Bridging Brings Better Bracing.

A structural member spanning across an opening in a floor system, supporting the ends of cut common joists and transferring their loads to adjacent trimmer joists.

• Used for stairways, chimneys, and other large openings.
• Orientation is perpendicular to common joists.
• Must be adequately sized and connected to trimmer joists.

Memory trick: Headers Hold, Trimmers Take, Common Cuts.

Heavy loads applied over a small area of a floor, such as those from hot tubs, pianos, or safes, requiring special structural consideration beyond typical uniform live loads.

• Often require custom engineering or specific IRC provisions.
• Standard framing is usually insufficient.
• May involve closer joist spacing, sistered joists, or structural beams.

Memory trick: Heavy Loads Need Holistic Engineering.

The minimum thickness of wood structural panel subflooring is determined by joist spacing and the type of finish flooring, to ensure adequate support and prevent deflection.

• Depends on joist spacing and finish type.
• 5/8 inch is common for 16" o.c. joists with direct resilient flooring.
• Refer to IRC Table R503.2.1.1(1) or similar.

Memory trick: Sixteen on center needs five-eighths strength.

The minimum vertical distance required by code between unencapsulated earth and the bottom of wood floor joists or beams in a crawl space.

• Prevents moisture migration into wood.
• Allows for adequate ventilation.
• Provides access for future inspections and repairs.

Memory trick: Earth to Wood: 18 for Joists, 12 for Girders.

Masonry chimney walls, excluding the flue lining, must have a minimum thickness of 4 inches of solid masonry units.

• Applies to masonry chimneys.
• Ensures structural stability and fire safety.
• Flue lining is a separate component and not included in this thickness.

Memory trick: A solid 'Four' inches of masonry makes a safe chimney wall.

For stairways with open risers, the opening between treads must be limited to prevent objects (specifically, a 4-inch sphere) from passing through, ensuring safety.

• Applies to open riser stairways.
• Prevents a 4-inch sphere from passing through.
• Ensures safety, especially for children.

Memory trick: Open risers need a '4-inch fence' to keep little ones safe.

For wood structural panel shear walls in Seismic Design Category D2, with 8d common nails at 4 inches on center at panel edges, the minimum nominal panel thickness is 7/16 inch.

• Seismic Design Category (SDC) influences shear wall requirements.
• Nail size and spacing are critical for shear capacity.
• Refer to IRC Table R602.10.4(1) for specific design values.

Memory trick: In SDC D2, a 'Seven-Sixteenths' panel with 8d nails holds strong.

Collar ties, which resist rafter separation at the ridge, have specific minimum size requirements based on code.

• Collar ties are required to be a minimum of 1x4.
• They are installed in the upper third of the rafter span.
• They resist rafter separation at the ridge.

Memory trick: Collar Ties: 'C' for 'Connect' the 'Ceiling' at the 'Top'.

1/4-inch thick wood paneling installed directly to studs requires a maximum stud spacing of 16 inches on center.

• Applies to thin wood paneling.
• Direct application to studs, no intermediate furring.
• Ensures flatness and prevents aesthetic defects.

Memory trick: Thin 'Quarter-inch' paneling needs 'Sixteen' inches of stud support.

The assumed maximum allowable vertical pressure that a specific type of soil can safely support, as listed in the IRC, without requiring a geotechnical analysis.

• IRC Table R401.4.1 provides these values.
• Used for sizing footings in the absence of a site-specific soils report.
• Clay/silt soils generally have lower bearing capacities.
• Values are conservative to ensure safety.

Memory trick: Clay and silt are weak, so remember 'fifteen hundred' for their feet.

Shaft walls enclosing plumbing or other penetrations that extend through more than one story in a residential building must have a minimum 1-hour fire-resistance rating.

• Applies to shafts not contained within a single dwelling unit.
• Prevents vertical fire and smoke spread.
• Rating is for the enclosure, not individual pipes.

Memory trick: A multi-story shaft needs 'One Hour' of fire resistance to protect the home.

The IRC specifies minimum clearance requirements for water closets to ensure accessibility and comfortable use, including a minimum distance from the center of the fixture to any side obstruction.

• Applies to water closets (toilets).
• Measured from the center of the fixture.
• Ensures adequate space for user and maintenance.

Memory trick: For the toilet, 'fifteen' inches to the side is keen for hygiene.

The smallest allowable vertical dimension for a concrete footing supporting a residential wall, as specified by building codes.

• Ensures adequate strength to distribute loads.
• Prevents punching shear failure.
• Specified in IRC R403.1.4.1.

Memory trick: For a footing, think six solid inches to stand on.

In areas with high seismic risk (Seismic Design Category D2), wood structural panel wall sheathing used for shear walls must meet a minimum thickness to provide sufficient lateral force resistance.

• Applies to shear walls resisting seismic forces.
• Thickness depends on seismic design category.
• Ensures structural integrity during earthquakes.

Memory trick: For D2 seismic, 'seven-sixteenths' is the wall's strong shield.

For 2x4 non-load-bearing interior walls with an unsupported height of 12 feet, the maximum stud spacing is 16 inches on center.

• Applies to non-load-bearing interior partition walls.
• Height significantly impacts allowable spacing.
• Refer to IRC Table R602.3(5) for specific stud spacing limits.

Memory trick: Twelve feet high, a 2x4 non-load wall needs to be 'Sixteen' inches tight.

The maximum distance between supports (rafters/trusses) that a given thickness and type of roof sheathing can span without excessive deflection.

• Determined by sheathing thickness and composition.
• Influenced by orientation (long dimension perpendicular/parallel).
• Governed by IRC Table R803.1 for wood structural panels.

Memory trick: Sheathing Span: 'S' for 'Spacing', 'S' for 'Strength', 'S' for 'Sheathing'.

The minimum nominal thickness required for an unreinforced foundation wall built from solid masonry units, based on its height and backfill conditions, as specified in the IRC.

• IRC Table R404.1.2(1) governs these requirements.
• Thickness depends on wall height and unbalanced backfill height.
• Ensures structural stability against lateral earth pressure and vertical loads.
• Unreinforced walls have stricter thickness limitations.

Memory trick: Unreinforced masonry needs 8 inches for 8 feet, like a double-8 bowling ball.

Concrete used for basement walls retaining earth must have a minimum specified compressive strength (f'c) of 2,500 psi.

• Applies to cast-in-place concrete basement walls.
• Ensures resistance to lateral earth pressure.
• Refer to IRC Tables R404.1.2(1) and R404.1.2(2).

Memory trick: For a strong basement wall, two thousand 'Five Hundred' psi is the concrete minimum.

A minimum 1/4-inch clear air space is required between moisture-sensitive exterior wall coverings and the water-resistive barrier.

• Applies to moisture-sensitive materials (e.g., wood siding, fiber cement siding).
• Promotes drainage and drying.
• Prevents moisture accumulation behind the siding.

Memory trick: Keep the 'Sensitive' walls 'Quarter' dry with an air gap.

A wall separating an attached garage from a dwelling unit must have a minimum fire-resistance rating to prevent the spread of fire. The IRC specifies materials and construction for this separation.

• Required for attached garages.
• Minimum 1/2-inch gypsum board on garage side.
• Ceilings also require fire separation if habitable space above.

Memory trick: Guard the Garage, Gypsum is Great!

2x4 studs used in load-bearing walls, supporting one floor and a roof, have a maximum unsupported height of 10 feet per 2021 IRC.

• Applies to exterior and interior load-bearing walls.
• Assumes typical residential loading conditions.
• Refer to IRC Table R602.3(5) for specific span and height limits.

Memory trick: Two-by-Four studs, supporting one floor, stand tall to 'Ten'.

The horizontal overlap required between adjacent rolls of felt underlayment, dependent on roof pitch.

• Side lap varies with roof pitch.
• Steeper pitches require less overlap.
• IRC R905.1.1 governs these requirements.

Memory trick: Underlayment Laps: 'Up' the 'Roof', 'Less' 'Overlap' for 'Side', 'More' for 'End'.

The smallest allowable internal dimension for a foundation drain pipe, as mandated by building codes to ensure adequate water flow.

• IRC R405.1 outlines foundation drainage requirements.
• Ensures sufficient capacity to remove groundwater.
• Prevents clogging and hydrostatic pressure buildup.
• A common code requirement for residential foundations.

Memory trick: A foundation drain needs a 'four-inch' pipe to keep the water flowing free.

The specific type of granular material required directly above a foundation drain to ensure proper water flow and prevent clogging.

• IRC R405.1 regulates foundation drainage.
• Crushed stone or gravel is required.
• Must extend at least 6 inches above the drain.
• Prevents fine soils from clogging the drain.

Memory trick: Drainage needs gravel on top, like a crunchy cereal, for water to flow free.

The minimum net area of ventilation openings required for a crawl space when no vapor retarder is installed on the ground surface.

• IRC R408.2 specifies ventilation requirements.
• Ratio is 1 square foot of opening per 150 square feet of crawl space area.
• Ensures proper air circulation to prevent moisture buildup.

Memory trick: Ventilation needs 150 friends to keep a crawl space dry, unless there's a vapor shield, then 1500 is fine.