CSLB General Building (B) — All Questions
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135 questions
A stair must rise a total of 108 inches from finished floor to finished floor. If each riser is designed at 7.2 inches, how many risers are required?
- a.14 risers
- b.15 risers✓
- c.18 risers
- d.12 risers
Number of risers equals total rise divided by riser height: 108 / 7.2 = 15 risers exactly. 12 risers would give a 9-inch riser (too tall); 14 risers gives about 7.7 inches (acceptable but not the designed 7.2); 18 risers gives only 6 inches, more than designed.
When a plumbing or mechanical run requires boring holes in load-bearing wall studs, the code limits bored hole diameter to no more than what fraction of the stud depth, unless the stud is doubled?
- a.60 percent
- b.70 percent
- c.50 percent
- d.40 percent✓
R602.6 allows bored holes up to 40 percent of the stud depth in exterior and bearing walls without further steps. Over 40 percent, the stud must be doubled, and no more than two successive doubled studs may be bored that way. 60 percent is the overall limit even then, 50 percent would still require doubling, and 70 percent is never allowed by this rule.2025 CA Residential Code §R602.6
For exterior wood decks, which material designation BEST indicates lumber suitable for the wet, ground-contact exposure of deck posts set near grade?
- a.Finger-jointed trim stock
- b.Preservative-treated lumber rated for ground contact✓
- c.Untreated standard framing lumber, since a heavy post section dries out faster than it can decay
- d.Kiln-dried interior-grade lumber
Deck posts near grade require preservative-treated lumber rated for ground contact to resist decay and insects. Kiln-dried interior lumber, untreated framing lumber, and finger-jointed trim are all unsuited to sustained moisture and will deteriorate.2025 CA Residential Code §R507.2
In a braced wall line using wood structural panel sheathing, which nailing change MOST directly increases the shear capacity of the wall?
- a.Decreasing panel edge nail spacing from 6 to 4 inches✓
- b.Using a smaller-diameter nail at the same spacing
- c.Removing nails at the panel field
- d.Increasing panel edge nail spacing from 4 to 6 inches
Tighter edge nailing, such as reducing spacing from 6 to 4 inches on center, transfers more shear per foot and increases the wall's capacity. Widening the spacing, removing field nails, or using thinner nails all reduce capacity rather than increase it.2025 CA Residential Code §R602.10.4
A common rafter has a horizontal run of 10 feet and a rise of 5 feet. What is the roof slope expressed as unit rise per 12 units of run?
- a.6:12✓
- b.12:12
- c.4:12
- d.3:12
Slope in rise-per-12 equals (rise / run) x 12 = (5 / 10) x 12 = 6, so the slope is 6:12. 3:12 and 4:12 are shallower than the actual ratio, and 12:12 would require the rise to equal the run.
In conventional roof framing with rafters bearing on exterior walls, what is the PRIMARY purpose of ceiling joists or an equivalent tie connecting opposing rafters?
- a.To provide attic storage capacity for the homeowner's belongings
- b.To align the ridge board vertically over the center of the span
- c.To resist rafter thrust that would otherwise push the walls outward✓
- d.To support the finished roofing weight only, and nothing else
Ceiling joists or rafter ties act in tension to resist the outward thrust that sloped rafters exert on the walls at their bearing. They are not solely for roofing weight, attic storage, or ridge alignment; without the tie the walls could spread and the ridge could sag.2025 CA Residential Code §R802.5
When anchoring wood ledgers or sill plates to masonry or concrete in a seismic design category, which fastener detail is MOST important for load transfer?
- a.Using properly sized and embedded anchors with edge distance and spacing per the approved design✓
- b.Using a single anchor centered on the plate, so that its pull is shared evenly toward both ends of the piece
- c.Attaching with construction adhesive alone, relying on the bond between the wood and the face of the masonry below
- d.Relying on masonry nails driven by hand, spaced closely enough that their combined grip holds the plate down
Load transfer into masonry or concrete depends on correctly sized anchors installed to the design embedment, edge distance, and spacing. Hand-driven masonry nails, adhesive alone, or a single central anchor cannot develop the required capacity and violate the engineered detailing.2025 CA Residential Code §R606
On a residential stairway, the MAXIMUM allowable variation between the largest and smallest riser height within a single flight is generally limited to what value?
- a.1 inch
- b.1/8 inch
- c.3/4 inch
- d.3/8 inch✓
Uniformity rules limit the difference between the largest and smallest riser (and largest and smallest tread) in a flight to no more than 3/8 inch, preventing trip hazards from uneven steps. 1/8 inch is stricter than required, while 3/4 inch and 1 inch exceed the limit and create dangerous inconsistency.2025 CA Residential Code §R318.7.5.1
Behind exterior cement plaster (stucco) on a wood-framed wall, the code generally requires how many layers of an approved water-resistive barrier over the sheathing?
- a.No barrier is required, because the sheathing behind the plaster already sheds water
- b.Two layers (equivalent) of water-resistive barrier✓
- c.Four layers
- d.One-half layer, with the paper run only across the lower part of the wall where splash lands
Because Portland cement plaster absorbs and holds water, the code generally requires two layers (or an equivalent) of water-resistive barrier behind stucco to protect the sheathing and framing. No barrier or a single half-layer is inadequate, and four layers is more than the code requires.2025 CA Residential Code §R703.7.3
Guards are required on a residential deck when the walking surface is located more than what height above the grade or surface below?
- a.30 inches✓
- b.24 inches
- c.18 inches
- d.12 inches
A guard is required where the deck walking surface is more than 30 inches above the grade or floor below, measured within a set horizontal distance. 12, 18, and 24 inches are all below the threshold that triggers a required guard.2025 CA Residential Code §R321.1.1
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Under conventional framing rules, solid-sawn floor joists deeper than a nominal 2x12 must have lateral support (blocking, bridging or a 1x3 strip) at intervals not exceeding what maximum spacing?
- a.8 feet on center along the joist span✓
- b.No blocking is ever required for solid-sawn joists
- c.12 feet on center along the joist span
- d.4 feet on center along the joist span
CRC R502.7.1: joists exceeding a nominal 2x12 can twist or buckle, so solid blocking, diagonal bridging or a continuous 1x3 strip must be installed at intervals not exceeding 8 feet. 4 feet is stricter than required; 12 feet exceeds the limit; claiming blocking is never required ignores the rule for deep members.2025 CA Residential Code §R502.7.1
In a wood-framed dwelling, fireblocking must be installed in concealed stud wall cavities at the ceiling and floor levels and, along the horizontal run, at intervals not exceeding what distance?
- a.10 feet✓
- b.4 feet
- c.20 feet
- d.6 feet
Fireblocking cuts off concealed draft openings so fire cannot spread quickly through wall cavities; horizontally it is required at intervals not exceeding 10 feet, plus at ceiling and floor levels. 4 and 6 feet are stricter than required, and 20 feet far exceeds the code limit, leaving an unbroken chimney-like cavity.2025 CA Residential Code §R302.11
When nailing wood structural panel subflooring or wall sheathing by hand, what is the typical fastener spacing required at the supported panel edges and at intermediate (field) supports?
- a.12 inches at edges and 24 inches in the field, a wider pattern meant to save fasteners and labor
- b.4 inches at edges and 8 inches in the field, a tighter pattern than ordinary panel attachment
- c.6 inches on center at edges and 12 inches on center in the field✓
- d.3 inches at edges and 6 inches in the field, the closest spacing used on heavily loaded panels
Standard panel attachment calls for fasteners at 6 inches on center along supported edges and 12 inches on center at intermediate supports. 12/24 is too sparse and would not develop the panel's design capacity; 3/6 and 4/8 are the tighter patterns reserved for high-load shear walls, not ordinary sheathing.2025 CA Residential Code §R602.3
In conventional roof framing, collar ties (or ridge straps) used to resist wind uplift and keep the ridge from separating are generally installed in what part of the attic space?
- a.In the upper third of the attic, near the ridge✓
- b.Flat across the bottom of the ceiling joists
- c.At the exact mid-height of the rafters only
- d.In the lower third, near the top of the exterior walls
Collar ties resist ridge separation and uplift and are placed in the upper third of the attic height, connecting opposing rafters near the ridge. Placing them low near the walls describes rafter ties (a different member); mid-height only and flat at the ceiling misstate the required location for collar ties.2025 CA Residential Code §R802
A common rafter must span a horizontal run of 8 feet and rise a vertical height of 6 feet from the top plate to the ridge. Ignoring overhang, what is the approximate line length of the rafter?
- a.14 feet
- b.10 feet✓
- c.12 feet
- d.11 feet
The rafter is the hypotenuse of a right triangle: length equals the square root of (8 squared plus 6 squared) = square root of (64 + 36) = square root of 100 = 10 feet. This is the classic 3-4-5 triangle scaled by two. 12 and 14 feet overstate the diagonal, and 11 feet does not match the exact calculation.
At the ends of a wood-framed shear wall, a hold-down device anchored to the foundation is installed primarily to resist which force?
- a.Thermal expansion of the wood framing
- b.Vertical dead load from the roof above pressing straight down through the wall to the foundation
- c.In-plane sliding of the whole wall along the sill as lateral load pushes it sideways off the plate
- d.Overturning and uplift at the wall ends during lateral loading✓
During earthquake or wind loading a shear wall tends to rotate, lifting one end; hold-downs anchor that end to the foundation to resist overturning and uplift. Gravity dead load is carried by studs and plates, sliding is resisted by anchor bolts, and thermal movement is not the function of a hold-down.2025 CA Residential Code §R602.10
For a conventional sill-plate anchor bolt set in a concrete foundation, what is the MINIMUM embedment depth of the bolt into the concrete?
- a.4 inches
- b.10 inches
- c.7 inches✓
- d.2 inches
Anchor bolts must extend at least 7 inches into the concrete or grouted masonry to develop adequate holding strength. 4 inches and 2 inches are too shallow to resist uplift and shear reliably, while 10 inches exceeds the minimum and is not the code-required figure.2025 CA Residential Code §R403.1.6
For a wood structural panel shear wall to develop its rated capacity, how must the panel edges be treated where sheets meet?
- a.Panels should be gapped and left unfastened at vertical joints so the sheets can move independently
- b.All panel edges must be backed by framing or blocking and nailed✓
- c.Edges may be left unsupported as long as the field is nailed
- d.Only the top and bottom edges need backing
Shear is transferred through fastened panel edges, so every panel edge must bear on framing or blocking and be nailed at the required spacing. Leaving vertical edges unsupported or unfastened, or backing only top and bottom, breaks the load path and drastically reduces the wall's shear capacity.2025 CA Residential Code §R602.10
Exterior wood siding, sheathing, or trim that is NOT preservative-treated or naturally durable must generally be kept at least how far above exposed earth?
- a.12 inches above finished grade
- b.1 inch above finished grade
- c.6 inches above finished grade✓
- d.Flush with grade is acceptable
To limit decay, untreated wood must be kept a minimum of 6 inches above exposed earth. One inch and flush contact invite moisture wicking and rot, while 12 inches is a larger clearance than the code minimum and is not the required figure.2025 CA Residential Code §R304.1
On a wood-framed wall receiving exterior cement plaster (stucco), a weep screed must be installed at the base of the wall at a MINIMUM of how high above adjacent earth and above paved surfaces?
- a.2 inches above earth and 4 inches above paved areas
- b.6 inches above earth and 6 inches above paved areas
- c.4 inches above earth and 2 inches above paved areas✓
- d.1 inch above both earth and paved areas
The weep screed lets moisture drain out at the wall base and must sit at least 4 inches above earth and 2 inches above paved surfaces. Reversing the numbers, using 1 inch, or requiring 6 inches everywhere misstates the code minimums that balance drainage with splash protection.2025 CA Residential Code §R703.7.2.1
When metal lath is applied to a wood-framed wall to receive three-coat cement plaster, the lath fasteners should penetrate the framing members by at least approximately how much?
- a.No penetration into framing is needed if the sheathing holds the lath
- b.1/8 inch
- c.1/4 inch
- d.3/4 inch✓
Lath must be firmly anchored so the heavy plaster does not sag or crack; fasteners should penetrate the supporting framing by about 3/4 inch. Penetrations of 1/8 or 1/4 inch are too shallow to hold the load, and relying on sheathing alone without engaging framing leaves the lath inadequately secured.2025 CA Residential Code §R703.7
Where an exterior deck beam bears on a supporting post, what is the BEST practice for the beam-to-post connection?
- a.Notch the post halfway and set the beam in the notch without fasteners
- b.Use a positive mechanical connection such as a post cap that ties beam to post✓
- c.Rely on gravity and the deck load to hold the beam in place
- d.Toenail the beam to the top of the post
A positive mechanical connector (post cap or equivalent hardware) transfers load and resists lateral displacement and uplift between beam and post. Toenailing is weak and splits wood, gravity alone provides no uplift or lateral resistance, and an unfastened notched bearing can let the beam shift or roll off the post.2025 CA Residential Code §R507.5
How many board feet are contained in 15 framing members that are each nominal 2x10 and 16 feet long? (Board feet per piece = nominal thickness in inches times nominal width in inches times length in feet, divided by 12.)
- a.375 board feet
- b.400 board feet✓
- c.300 board feet
- d.350 board feet
Each piece = (2 x 10 x 16) / 12 = 320 / 12 = 26.67 board feet. Multiplied by 15 pieces = 400 board feet. The other choices result from dropping the piece count or mis-multiplying the thickness-width-length product.
Under the raised floor of a dwelling, short stud walls between the foundation and the first-floor framing (cripple walls) exceeding a nominal height must be braced primarily to resist what?
- a.Lateral (seismic and wind) forces that could cause the walls to rack and the house to slide off✓
- b.Frost heave beneath the slab lifting the framing above it as trapped ground moisture freezes and expands in cold weather
- c.Termite entry at the mud sill, where the wood framing comes closest to the ground and is easiest for insects to reach
- d.Vertical settlement of the footing as the soil beneath it compresses and the short wall above is carried down
Cripple walls are a known weak point in earthquakes; when tall enough they must be braced with wood structural panels to resist lateral racking that can drop a house off its foundation. Settlement is a footing issue, frost heave concerns cold-climate slabs, and termite entry is addressed by other measures, not bracing.2025 CA Residential Code §R602.9
On a jobsite, prefabricated wood roof or floor trusses must NOT be treated in which of the following ways?
- a.Braced permanently and temporarily as specified by the design
- b.Stored off the ground and kept from prolonged weather exposure so the lumber and plates stay dry until they are set
- c.Cut, notched, or drilled through chords or webs to run a duct, without the truss designer's approval✓
- d.Handled with spreader bars to avoid bending during a lift, keeping the long chords straight while the crane swings them
Truss members are engineered; cutting, notching, or drilling chords or webs without the designer's approval can void the design and cause collapse. Using spreader bars, following the specified bracing, and proper storage are all correct handling practices.2025 CA Residential Code §R502.11
A residential stairway must rise a total of 105 inches from finished floor to finished floor. Using the maximum allowable riser height of 7-3/4 inches, what is the MINIMUM number of risers, and the resulting even riser height?
- a.14 risers at 7.5 inches each✓
- b.12 risers at about 8.75 inches each
- c.13 risers at about 8.08 inches each
- d.13 risers at about 7.75 inches each
Divide 105 by the 7.75-inch maximum: 105 / 7.75 = 13.5, which rounds up to 14 risers because you cannot exceed the maximum. 105 / 14 = 7.5 inches per riser, within the limit. Thirteen risers would each be about 8.08 inches, exceeding the 7.75-inch cap; twelve risers at 8.75 inches also exceed the maximum.
On a stairway that turns using winder treads, what is the MINIMUM tread depth measured at the walk line, and the MINIMUM depth at any point of the narrow end?
- a.12 inches at the walk line and 8 inches at the narrow end
- b.7 inches at the walk line and 4 inches at the narrow end
- c.10 inches at the walk line and 6 inches at the narrow end✓
- d.11 inches at the walk line and 10 inches at the narrow end
Winder treads must provide at least 10 inches of depth at the walk line (typically 12 inches from the narrow side) and never less than 6 inches at any point. The other options either overstate the required depths or allow a dangerously narrow 4-inch section at the inside of the turn.2025 CA Residential Code §R318.7.5.2.1
On an open stair with a guard, the triangular opening formed by the tread, riser, and bottom rail is limited so that what size sphere cannot pass through?
- a.An 8-inch-diameter sphere
- b.A 6-inch-diameter sphere✓
- c.A 4-inch-diameter sphere
- d.A 5-inch-diameter sphere
For the special triangular opening at the tread, riser, and bottom guard rail, the code allows a slightly larger limit: a 6-inch sphere must not pass. The general 4-inch sphere applies to other guard openings, while 5- and 8-inch limits are not recognized values for this location.2025 CA Residential Code §R321.1.3
In conventional wall framing, where two members of a double top plate are spliced (joints occur), the upper and lower plate joints must be offset by at least how much?
- a.12 inches
- b.24 inches✓
- c.48 inches
- d.6 inches
Offsetting the top-plate joints at least 24 inches ties the wall together and keeps a continuous load path along the plate. A 12- or 6-inch offset leaves the splices too close and weak, while 48 inches is more than required and is not the specified minimum.2025 CA Residential Code §R602.3.2
Behind most exterior siding on a wood-framed wall, the code requires a water-resistive barrier equivalent to at least what?
- a.One layer of No. 15 asphalt felt or an approved equivalent✓
- b.A continuous rigid steel sheet
- c.Three layers of building paper
- d.No barrier as long as the siding laps are caulked, leaving the sealant to carry water off the wall
The minimum water-resistive barrier is one layer of No. 15 asphalt felt or an approved equivalent house wrap, lapped to shed water. Three layers exceed the general minimum, a steel sheet is not a required WRB, and caulked laps alone do not replace a continuous barrier behind the siding.2025 CA Residential Code §R703.2
A roof is designed with a 4:12 slope (4 inches of vertical rise for every 12 inches of horizontal run). If the horizontal run from the wall to the ridge is 15 feet, what is the total vertical rise?
- a.6 feet
- b.4 feet
- c.3 feet
- d.5 feet✓
Rise equals run times the slope ratio: 15 feet x (4/12) = 15 x 0.333 = 5 feet. The other answers come from applying the wrong ratio or misplacing the run and rise in the slope fraction.
When notching or boring a solid-sawn floor joist for a pipe, which limitation applies to protect the joist's strength?
- a.Notches may be any depth as long as they are on the top edge of the joist, where the wood is in compression
- b.Notches at the ends may not exceed one-fourth of the joist depth, and notches are not permitted in the middle third of the span✓
- c.A hole may be drilled within 1 inch of the joist edge wherever the pipe run needs to cross the joist
- d.Bored holes may be located anywhere and up to half the joist depth, including the middle of the span
To keep bending strength, end notches are limited to one-fourth the joist depth and no notches are allowed in the middle third where bending stress peaks; bored holes are limited to one-third the depth and kept back from edges. Unlimited notch depth, half-depth holes anywhere, or drilling within an inch of the edge all weaken the joist beyond code limits.2025 CA Residential Code §R502.8.1
Fasteners and metal connectors that contact preservative (pressure) treated deck lumber must have what property to prevent premature failure?
- a.A bright, uncoated bare-steel finish, chosen for a clean look where the hardware stays visible
- b.Corrosion resistance, such as hot-dipped galvanized or stainless steel✓
- c.The lowest possible cost regardless of coating, so the fastener budget on a large deck stays down
- d.Aluminum contact directly against the treated wood, relying on the light metal to shed weight
Modern treatment chemicals are corrosive to unprotected steel, so fasteners and connectors must be corrosion resistant, typically hot-dipped galvanized or stainless. Choosing by cost alone, using bare steel, or placing aluminum in direct contact all accelerate corrosion and can fail the connection.2025 CA Residential Code §R304.3.1
In braced-wall and shear-wall construction resisting seismic loads, anchor bolts at the sill plate are commonly required to have what added component for load transfer?
- a.A steel plate washer (for example about 3 by 3 inches) between the nut and the sill plate✓
- b.A thin fender washer only
- c.No washer, because the nut alone is sufficient to clamp the sill plate down onto the foundation below it
- d.A plastic sleeve around the bolt to keep the threads clean and let the anchor turn freely in the hole
A larger square steel plate washer spreads the clamping force and keeps the sill from splitting or pulling over the bolt head during shaking, improving lateral load transfer. A plastic sleeve does nothing structurally, a thin fender washer is undersized for shear walls, and omitting the washer lets the nut pull through the wood.2025 CA Residential Code §R602.11.1
A roof rises 3 inches for every 12 inches of horizontal run. Expressed as a percentage, what is the slope of this roof?
- a.25 percent✓
- b.3 percent
- c.33 percent
- d.12 percent
Percent slope equals rise divided by run times 100: (3 / 12) x 100 = 25 percent. Thirty-three percent would be a 4:12 slope, 3 percent and 12 percent come from misreading the rise-over-run ratio.