CSLB General Building (B) — All Questions
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215 questions
A concrete mix is batched with 620 pounds of cement per cubic yard. To hold the water-cement (w/c) ratio at a MAXIMUM of 0.45, what is the greatest amount of water that may be used per cubic yard?
- a.About 279 pounds✓
- b.About 344 pounds
- c.About 248 pounds
- d.About 310 pounds
The w/c ratio is water weight divided by cement weight, so maximum water = 0.45 x 620 = 279 lb. 248 lb corresponds to a 0.40 ratio, 310 lb to 0.50, and 344 lb to 0.55, all of which miss the specified 0.45 limit.2025 CA Building Code (CBC) Chapter 19 (Concrete)
An accelerating admixture such as a non-chloride accelerator is added to a concrete mix PRIMARILY to:
- a.Delay the initial set so concrete can be hauled a long distance before it stiffens in the drum
- b.Reduce the amount of mixing water needed for a given slump without stiffening the mix
- c.Speed up early set and strength gain, which is useful in cold weather✓
- d.Entrain microscopic air bubbles to resist freeze-thaw damage in exposed exterior concrete
Accelerators shorten setting time and boost early strength, which helps when placing in cold conditions. Reducing water is the job of a water reducer, delaying set is a retarder's role, and entraining air bubbles is done by an air-entraining admixture.2025 CA Building Code (CBC) Chapter 19 (Concrete)
During hot-weather placement with a long haul time, a set-retarding admixture is used mainly to:
- a.Provide freeze-thaw protection in cold climates by building durability into the hardened paste
- b.Delay setting so the concrete stays workable longer✓
- c.Permanently reduce the water needed in the mix
- d.Increase the concrete's final compressive strength once it has fully cured
A retarder slows the hydration reaction so fresh concrete remains workable during long hauls or hot weather. It does not raise final strength, is not a water reducer, and offers no freeze-thaw benefit.2025 CA Building Code (CBC) Chapter 19 (Concrete)
The PRIMARY purpose of an isolation (expansion) joint around a column or against an existing wall in a slab-on-grade is to:
- a.Let the slab move independently of the column or wall without cracking✓
- b.Serve as the location where fresh concrete bonds to hardened concrete when a pour is stopped and resumed
- c.Transfer bending loads directly into the column base
- d.Create a decorative pattern in the finished surface
An isolation joint fully separates the slab from a fixed element so each can move independently, preventing restraint cracking. It is not meant to transfer load, is not primarily decorative, and a bonded interface is a construction joint, not an isolation joint.2025 CA Building Code (CBC) Chapter 19 (Concrete)
A construction joint in a concrete structure is BEST described as:
- a.A saw-cut groove that controls where random shrinkage cracks form
- b.A planned interface where one concrete placement stops and the next begins✓
- c.A gap filled with compressible material to allow thermal movement
- d.A gap left around plumbing penetrations through a slab
A construction joint is the deliberate stopping point between separate concrete pours, often keyed or doweled to transfer load. A control joint is the saw-cut groove, an expansion/isolation joint uses compressible filler, and neither describes a penetration gap.2025 CA Building Code (CBC) Chapter 19 (Concrete)
Which curing method retains moisture in fresh concrete by forming a sealing film on the surface after finishing?
- a.Spraying a liquid membrane-forming curing compound✓
- b.Fogging the surface with a fine water spray to replace the moisture leaving the slab
- c.Ponding water on top of a flat slab and holding it there while the concrete gains strength
- d.Covering the surface with continuously wet burlap that is rewetted as it dries out
A liquid membrane-forming compound leaves a thin film that seals in mix water so hydration continues. Ponding, wet burlap, and fogging all cure by adding external water rather than sealing the surface.2025 CA Building Code (CBC) Chapter 19 (Concrete)
A No. 5 reinforcing bar has a nominal diameter of 5/8 inch. If the specified tension lap splice is 40 bar diameters, what is the MINIMUM lap length?
- a.About 20 inches
- b.About 25 inches✓
- c.About 30 inches
- d.About 15 inches
Lap = 40 x 5/8 in = 40 x 0.625 = 25 inches. Using 24 or 32 bar diameters would give 15 or 20 inches, and 48 diameters would give 30 inches, so only 25 inches matches the 40-diameter requirement.2025 CA Building Code (CBC) Chapter 19 (Concrete)
For a typical residential interior slab-on-ground, what is a common MINIMUM slab thickness?
- a.8 inches
- b.5 inches
- c.3-1/2 inches✓
- d.6 inches
Residential concrete floor slabs on ground are commonly required to be at least 3-1/2 inches thick. The greater thicknesses listed apply to heavier-duty slabs but exceed the ordinary minimum.2025 CA Residential Code (CRC) R506 (Concrete Floors on Ground)
When placing concrete in cold weather, fresh concrete must generally be protected from freezing until it reaches a compressive strength of at least about:
- a.1,500 psi
- b.500 psi✓
- c.3,000 psi
- d.100 psi
Concrete is vulnerable to permanent damage if it freezes before reaching roughly 500 psi, so it must be kept above freezing until that early strength is achieved. 100 psi is too low to resist damage, while 1,500 and 3,000 psi are well beyond the point where freezing is critical.2025 CA Building Code (CBC) Chapter 19 (Concrete)
During hot-weather concreting, plastic shrinkage cracking is BEST prevented by:
- a.Reducing surface moisture loss by shading, wind breaks, and prompt curing✓
- b.Delaying all curing until the next day
- c.Increasing the mixing water to raise the slump so the crew can finish the surface with less effort
- d.Adding an accelerating admixture to speed the set so the slab hardens before the crew leaves
Plastic shrinkage cracks form when the surface dries faster than bleed water rises, so limiting evaporation with shading, wind breaks, fog, and prompt curing is the fix. Adding water weakens the concrete, an accelerator worsens rapid drying, and delaying curing increases moisture loss.2025 CA Building Code (CBC) Chapter 19 (Concrete)
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Six cylindrical concrete piers are each 18 inches in diameter and 4 feet deep. Approximately how many cubic yards of concrete are needed for all six?
- a.About 1.2 cubic yards
- b.About 1.6 cubic yards✓
- c.About 0.8 cubic yards
- d.About 2.4 cubic yards
Radius = 9 in = 0.75 ft, so each pier = 3.14 x 0.75^2 x 4 = 7.07 ft^3; six piers = 42.4 ft^3; divided by 27 = about 1.6 cubic yards. The other values result from using the diameter as radius or omitting the pier count.2025 CA Building Code (CBC) Chapter 19 (Concrete)
A rectangular slab measures 20 feet by 25 feet and is 5 inches thick. Approximately how many cubic yards of concrete does it require?
- a.About 6.3 cubic yards
- b.About 11.5 cubic yards
- c.About 9.3 cubic yards
- d.About 7.7 cubic yards✓
Area = 20 x 25 = 500 ft^2; thickness = 5/12 = 0.4167 ft; volume = 208.3 ft^3; divided by 27 = about 7.7 cubic yards. A 4-inch slab would give 6.3 and a 6-inch slab 9.3, so only the 5-inch case yields 7.7.2025 CA Building Code (CBC) Chapter 19 (Concrete)
Mechanical vibration of freshly placed concrete is done PRIMARILY to:
- a.Speed up the chemical curing reaction
- b.Increase the water-cement ratio for easier finishing so the surface can be troweled smooth sooner
- c.Consolidate the mix and drive out entrapped air pockets and voids✓
- d.Add entrained air for freeze-thaw resistance
Vibration consolidates the concrete around reinforcement and expels entrapped air so the mass is dense and sound. Over-vibration actually causes segregation; it does not change the w/c ratio, speed curing, or add entrained air.2025 CA Building Code (CBC) Chapter 19 (Concrete)
Final troweling or hard floating of a concrete slab should NOT begin until:
- a.Rebar is placed at the bottom of the slab
- b.The concrete has fully cured for 28 days
- c.A curing compound has been sprayed on
- d.Surface bleed water has evaporated✓
Finishing must wait until bleed water has left the surface; working the water back in traps it under the finished layer and produces scaling and a weak surface. The other choices confuse curing timing, reinforcement placement, and curing-compound steps with the finishing window.2025 CA Building Code (CBC) Chapter 19 (Concrete)
For general-use receptacles along a dwelling wall, the spacing rule requires that no point measured horizontally along the wall line be more than what distance from a receptacle?
- a.6 feet✓
- b.4 feet
- c.8 feet
- d.12 feet
The rule places receptacles so no point along the wall is more than 6 feet from one, which is why receptacles fall at most 12 feet apart. 4 and 8 feet misstate the limit, and 12 feet is the maximum spacing between receptacles, not the distance to the nearest one.2025 CA Electrical Code (CEC) Art. 210 (Branch Circuits)
Along a kitchen countertop, receptacle outlets must be placed so that no point along the counter wall line is more than what distance from a receptacle?
- a.24 inches✓
- b.18 inches
- c.12 inches
- d.36 inches
Kitchen counter receptacles are spaced so no point along the wall counter is more than 24 inches from an outlet, meaning outlets are no more than 48 inches apart. 12 and 18 inches are too strict, and 36 inches exceeds the code limit.2025 CA Electrical Code (CEC) Art. 210 (Branch Circuits)
What is the MINIMUM headroom (vertical clearance) required for the working space about a service panel or other electrical equipment rated 600 volts or less?
- a.5 feet 0 inches
- b.7 feet 6 inches
- c.4 feet 6 inches
- d.6 feet 6 inches✓
The code requires at least 6 feet 6 inches of headroom in the working space so a worker can stand and access equipment safely. 5 feet and 4 feet 6 inches are too low, and 7 feet 6 inches overstates the requirement.2025 CA Electrical Code (CEC) §110.26 (Working Space)
A feeder must supply a continuous load of 32 amperes plus a noncontinuous load of 40 amperes. What is the MINIMUM feeder conductor ampacity required?
- a.90 amperes
- b.72 amperes
- c.76 amperes
- d.80 amperes✓
Continuous load is taken at 125 percent, so 32 x 1.25 = 40, plus the 40-ampere noncontinuous load gives 80 amperes minimum. Simply adding 72 ignores the continuous-load factor, and 76 or 90 misapply it.2025 CA Electrical Code (CEC) Art. 215 (Feeders)
When 7 current-carrying conductors are bundled together in a single raceway, their allowable ampacity must be adjusted to what percent of the base value?
- a.80 percent
- b.90 percent
- c.100 percent
- d.70 percent✓
For 7 through 9 current-carrying conductors the adjustment factor is 70 percent, because heat cannot dissipate as readily when many conductors share a raceway. 100, 90, and 80 percent apply to fewer conductors (3 or fewer, 4 to 6, respectively).2025 CA Electrical Code (CEC) §310.15 (Conductor Ampacity)
In a dwelling, 125-volt receptacles must have GFCI protection when installed within what distance of the outside edge of a kitchen or wet-bar sink?
- a.10 feet
- b.3 feet
- c.6 feet✓
- d.8 feet
Receptacles within 6 feet of the outside edge of a sink require GFCI protection because of the shock hazard near water. 3 feet is too short, and 8 or 10 feet exceed the code trigger distance.2025 CA Electrical Code (CEC) Art. 210 (GFCI Protection)
Which of the following branch circuits is MOST clearly required to have arc-fault circuit-interrupter (AFCI) protection?
- a.The circuit for an outdoor landscape light
- b.120-volt outlets in a bedroom✓
- c.A dedicated bathroom exhaust-fan circuit outdoors
- d.A 240-volt circuit serving a water heater
AFCI protection is required for most 120-volt outlets in dwelling living areas such as bedrooms, where hidden arcing in wiring is a fire risk. Outdoor and 240-volt equipment circuits are not the primary target of the AFCI requirement.2025 CA Electrical Code (CEC) Art. 210 (AFCI Protection)
A device box contains four 12 AWG circuit conductors, two 12 AWG equipment grounding conductors, and one duplex receptacle. Using 2.25 cubic inches per 12 AWG conductor, what MINIMUM box volume is required?
- a.About 13.5 cubic inches
- b.About 20.25 cubic inches
- c.About 18.0 cubic inches
- d.About 15.75 cubic inches✓
Count 4 for the circuit conductors, 1 for all grounding conductors combined, and 2 for the yoke (device) based on the largest conductor, giving 7 units x 2.25 = 15.75 cubic inches. Counting the grounds individually or the device as one raises or lowers the total incorrectly.2025 CA Electrical Code (CEC) §314.16 (Box Fill)
A 240-volt, 30-ampere dedicated circuit is wired with copper conductors. Under typical residential conditions, what is the MINIMUM copper conductor size that matches this 30-ampere circuit?
- a.12 AWG
- b.14 AWG
- c.10 AWG✓
- d.8 AWG
A 30-ampere circuit is normally served by 10 AWG copper, which carries 30 amperes under standard conditions. 14 and 12 AWG are limited to 15 and 20 amperes, while 8 AWG is larger than necessary.2025 CA Electrical Code (CEC) Art. 240 (Overcurrent Protection)
In new dwelling construction, 15- and 20-ampere, 125-volt receptacles installed in normally accessible locations must generally be:
- a.Rated for 20 amperes only
- b.Tamper-resistant✓
- c.Isolated-ground type
- d.Weather-resistant only
Code requires listed tamper-resistant receptacles in dwellings to protect children from inserting objects into the slots. Weather resistance applies to damp/wet locations, 20-ampere rating is not universally required, and isolated-ground types serve sensitive equipment, not general safety.2025 CA Electrical Code (CEC) §406.12 (Tamper-Resistant Receptacles)
For a 2-inch fixture drain, what is a common MAXIMUM developed length of the trap arm (from the trap weir to the vent)?
- a.5 feet✓
- b.3 feet
- c.8 feet
- d.12 feet
The plumbing code table generally allows a 2-inch trap arm up to about 5 feet of developed length before the vent, keeping the trap seal from being siphoned. 3 feet is overly restrictive for a 2-inch pipe, while 8 and 12 feet exceed the allowed length and risk self-siphonage.2025 CA Plumbing Code (CPC) Chapter 10 (Traps and Interceptors)
The drainage fixture unit (DFU) value assigned to a plumbing fixture PRIMARILY represents:
- a.A measure of the probable drainage load the fixture contributes to the system✓
- b.The number of vents the fixture requires on the drainage system
- c.The physical trap seal depth of the fixture in inches of water
- d.The minimum working water pressure the fixture needs to operate
A DFU is a relative measure of the discharge load a fixture places on the drainage system, used to size pipes. It does not describe trap seal depth, supply pressure, or vent count.2025 CA Plumbing Code (CPC) Chapter 7 (Sanitary Drainage)
A horizontal branch drain must carry fixtures totaling 14 drainage fixture units. If a 2-inch pipe is rated for up to 6 DFU and a 3-inch pipe for up to 20 DFU, what is the MINIMUM pipe size?
- a.4 inches
- b.2 inches
- c.1-1/2 inches
- d.3 inches✓
Because 14 DFU exceeds the 6-DFU capacity of a 2-inch pipe, the next size that handles the load is the 3-inch pipe (up to 20 DFU). A 4-inch pipe would work but is larger than the minimum required.2025 CA Plumbing Code (CPC) Chapter 7 (Sanitary Drainage)
A cleanout on a 4-inch drain line must have a MINIMUM clearance in front of it for rodding of about:
- a.18 inches
- b.12 inches
- c.24 inches✓
- d.30 inches
CPC §707.9 requires a clear space of at least 24 inches by 24 inches in front of a cleanout on piping larger than 2 inches, so a rodding tool can be used. 18 inches by 18 inches applies to piping 2 inches or smaller, 12 inches is below both, and 30 inches is more than this section requires in front of the cleanout.2025 CA Plumbing Code (CPC) §707.9
When strapping a tank-type water heater against seismic movement, the lower strap must be placed at least how far above the water heater's controls (thermostat/burner)?
- a.4 inches✓
- b.2 inches
- c.3 inches
- d.1 inch
The lower seismic strap must sit within the bottom third of the tank but at least 4 inches above the controls so it does not interfere with the thermostat or burner. Smaller clearances risk contacting the control area.2025 CA Plumbing Code (CPC) §507 (Water Heaters)
When sizing fuel-gas piping to appliances, the two governing factors are the total gas demand (Btu/hr) and:
- a.The number of shutoff valves installed on the branches feeding each appliance
- b.The ambient room temperature in the space where the appliance is located
- c.The developed (longest) length of the piping run✓
- d.The color of the pipe coating used to mark the line as fuel gas
Gas pipe is sized from a table using the total connected demand and the developed length to the farthest appliance, which together set the required diameter. Coating color, room temperature, and valve count do not govern the pipe size.2025 CA Plumbing Code (CPC) Chapter 12 (Fuel Gas)
A sediment trap (drip leg) installed in the gas supply just ahead of an appliance functions PRIMARILY to:
- a.Serve as the required appliance shutoff valve that the installer closes to work on the unit
- b.Reduce the gas pressure to the appliance down to the value stamped on its rating plate
- c.Catch moisture and debris before they reach the appliance controls✓
- d.Vent excess gas to the outdoors
The sediment trap is a short capped extension that collects dirt and condensate so they do not clog the appliance valve or orifices. It does not regulate pressure, vent gas, or replace the shutoff valve.2025 CA Plumbing Code (CPC) Chapter 12 (Fuel Gas)
A backwater valve on a building drain is required PRIMARILY where:
- a.A fixture is on the top floor of a multi-story building and drains the longest distance to the sewer
- b.The building has more than one cleanout
- c.The water heater lacks a T&P relief valve
- d.Fixtures are located below the level of the next upstream sewer manhole cover✓
A backwater valve protects low fixtures that sit below the upstream manhole rim by preventing sewage from backing up into them during a surcharge. Top-floor fixtures, cleanout count, and water-heater valves are unrelated to this requirement.2025 CA Plumbing Code (CPC) §710 (Backwater Valves)
A vent pipe that penetrates the roof in an area without significant snowfall must extend at least how far above the finished roof surface?
- a.4 inches
- b.2 inches
- c.1 inch
- d.6 inches✓
The code generally requires vents to terminate at least 6 inches above the roof so debris and water do not block the opening. The smaller heights would leave the vent too close to the roofing to function reliably.2025 CA Plumbing Code (CPC) §906 (Vent Termination)
Shower and tub-shower control valves must be pressure-balancing or thermostatic types and are required to limit the water temperature to a MAXIMUM of:
- a.120 degrees F✓
- b.130 degrees F
- c.150 degrees F
- d.140 degrees F
These anti-scald valves must cap outlet temperature at 120 degrees F to protect bathers from burns. The higher values would exceed the safe limit and defeat the purpose of the valve.2025 CA Plumbing Code (CPC) §408 (Showers)
Flexible air ducts must be supported at MAXIMUM intervals of about what distance to prevent excessive sagging?
- a.10 feet
- b.4 feet✓
- c.18 inches
- d.3 feet
Flexible duct is typically supported at intervals not exceeding about 4 feet, limiting sag to roughly a half-inch per foot between supports. Closer spacing is unnecessary and 10 feet would allow excessive sag that restricts airflow.2025 CA Mechanical Code (CMC) §603 (Air Ducts)
An air-conditioning unit is rated at 36,000 Btu/hr of cooling capacity. Since one ton of cooling equals 12,000 Btu/hr, what is its capacity in tons?
- a.3 tons✓
- b.5 tons
- c.2 tons
- d.4 tons
Dividing 36,000 by 12,000 gives exactly 3 tons of cooling. 2 tons would be 24,000 Btu/hr and 4 tons would be 48,000 Btu/hr, so only 3 tons matches the rating.2025 CA Mechanical Code (CMC) Chapter 11 (Refrigeration)
A cooling-coil condensate drain line must slope toward its point of discharge a MINIMUM of about:
- a.1/2 inch per foot
- b.3/8 inch per foot
- c.1 inch per foot
- d.1/8 inch per foot✓
Condensate drains are generally required to slope at least 1/8 inch per foot so water flows out by gravity without pooling. Steeper slopes are acceptable but not the minimum requirement.2025 CA Mechanical Code (CMC) §310 (Condensate)
An air-side economizer on an HVAC system provides energy savings PRIMARILY by:
- a.Recovering heat from exhaust air in winter
- b.Using cool outdoor air for free cooling when conditions allow✓
- c.Filtering fine particulates from the supply air
- d.Raising refrigerant pressure for faster cooling
An economizer brings in cool outside air to meet cooling loads without running the compressor, saving energy when outdoor conditions are favorable. It is not primarily a heat-recovery, pressure-boost, or filtration device.2025 CA Energy Code, Title 24 Part 6
Under the California Energy Code, a residential bathroom exhaust fan that runs continuously must provide a MINIMUM airflow of:
- a.10 cfm
- b.20 cfm✓
- c.50 cfm
- d.100 cfm
Table 150.0-F sets 20 cfm for a bathroom with continuous exhaust. 50 cfm is the rate for a demand-controlled fan that runs only when switched on (Table 150.0-E). 10 cfm falls short of the table, and 100 cfm is far above it.2025 CA Energy Code §150.0(o), Table 150.0-F
The outlet of a bathroom or clothes-dryer environmental exhaust duct must terminate:
- a.Inside a ventilated crawl space where the crawl vents can carry the moisture away
- b.Into the return-air plenum of the furnace so the blower disperses the exhaust
- c.Inside the attic space above the insulation where roof vents can carry the air off
- d.Outdoors, and a minimum distance from openings into the building✓
Environmental exhaust must discharge to the outdoors and be kept a minimum distance (commonly 3 feet) from doors, windows, and other openings so moist or lint-laden air is not drawn back in. Terminating in an attic, plenum, or crawl space is prohibited.2025 CA Mechanical Code (CMC) §504 (Environmental Exhaust)
In a dwelling, makeup air must generally be provided for a kitchen exhaust hood once its rated airflow exceeds about:
- a.400 CFM✓
- b.100 CFM
- c.50 CFM
- d.150 CFM
Hoods exhausting more than about 400 CFM can depressurize a tight house and backdraft combustion appliances, so makeup air is required above that threshold. The lower values are typical small-fan flows that do not trigger the requirement.2025 CA Mechanical Code (CMC) §505 (Domestic Range Hoods)
Condensate from a high-efficiency (condensing) gas furnace is mildly acidic, so before or as it is discharged to an approved drain it should be:
- a.Piped into the combustion-air intake so the burner draws it back through the heat exchanger
- b.Returned to the gas supply line so it leaves with the fuel on its way to the burner
- c.Neutralized or routed to an approved corrosion-resistant drain✓
- d.Discharged onto the roof surface
Condensing-furnace condensate is acidic and can corrode metal drains, so it is neutralized and/or sent to an approved corrosion-resistant drain. Routing it to the air intake, roof, or gas line is unsafe and improper.2025 CA Mechanical Code (CMC) §310 (Condensate)
A continuous membrane roof (such as built-up or single-ply) is generally required instead of shingles when the roof slope is LESS THAN about:
- a.2:12✓
- b.6:12
- c.1:12
- d.4:12
Slopes below about 2:12 are considered low-slope and shed water too slowly for shingles, so a continuous membrane system is required. Slopes of 4:12 and 6:12 are steep-slope and suited to shingles.2025 CA Residential Code (CRC) R905 (Roof Coverings)
Where an ice barrier is required, it must extend from the eave edge to a point at least how far inside the exterior wall line of the building?
- a.36 inches
- b.12 inches
- c.6 inches
- d.24 inches✓
The ice barrier must reach at least 24 inches inside the interior face of the exterior wall so that ice damming at the eave cannot force water under the roofing into the building. 12 and 6 inches are too short, and 36 inches exceeds the minimum.2025 CA Residential Code (CRC) R905.1.2 (Ice Barriers)
For asphalt shingles installed on slopes between 2:12 and 4:12, the underlayment must be applied as:
- a.Two layers (doubled) for added protection✓
- b.No underlayment is needed at this slope
- c.A continuous membrane only, without shingles
- d.A single layer, same as steeper slopes
Low-to-moderate slopes between 2:12 and 4:12 require doubled underlayment because water drains more slowly and is more likely to back up under the shingles. A single layer applies only to steeper slopes, and omitting underlayment is never allowed.2025 CA Residential Code (CRC) R905.2 (Asphalt Shingles)
An enclosed attic has 1,500 square feet of area. Using the 1/150 rule with no vapor retarder, what MINIMUM net free ventilating area is required?
- a.7.5 square feet
- b.3 square feet
- c.5 square feet
- d.10 square feet✓
Under the 1/150 rule, required vent area = 1,500 / 150 = 10 square feet of net free area. Using the 1/300 rule would give 5 square feet, which applies only when balanced venting or a vapor retarder is used.2025 CA Residential Code (CRC) R806 (Roof Ventilation)
A roof has 3,150 square feet of surface to cover. Including a 10 percent allowance for waste and hips, how many roofing squares of material should be ordered?
- a.About 31.5 squares
- b.About 33 squares
- c.About 38 squares
- d.About 35 squares✓
One square equals 100 square feet, so 3,150 sq ft = 31.5 squares; adding 10 percent gives 31.5 x 1.10 = about 34.7, rounded up to 35 squares. Ordering 31.5 or 33 ignores or underestimates waste.2025 CA Residential Code (CRC) R905 (Roof Coverings)
At the rake (gable) edge of a shingle roof, the drip edge should be installed:
- a.Under the underlayment
- b.Behind the fascia board only, so the metal edge stays out of sight
- c.Over the top of the underlayment✓
- d.Only where gutters are present
At rakes the drip edge is installed over the underlayment, while at the eaves it goes under the underlayment; this layering directs water off the edge correctly. Restricting it to gutter locations or behind the fascia does not meet the requirement.2025 CA Residential Code (CRC) R905.2.8.5 (Drip Edge)
In a basic (non-high-wind) zone, standard asphalt shingles are typically fastened with a MINIMUM of how many nails per shingle?
- a.2 nails
- b.6 nails
- c.5 nails
- d.4 nails✓
Standard three-tab shingles normally require at least 4 fasteners per shingle in basic wind areas. Two nails is insufficient, while 5 or 6 nails are used only in high-wind zones or with specific manufacturer requirements.2025 CA Residential Code (CRC) R905.2.6 (Fasteners)
A simple gable roof covers a building 24 feet by 40 feet in plan. At a 6:12 pitch (slope factor 1.118), what is the approximate total roof surface area?
- a.About 960 square feet
- b.About 1,073 square feet✓
- c.About 1,040 square feet
- d.About 1,000 square feet
The plan footprint is 24 x 40 = 960 sq ft; multiplying by the 6:12 slope factor of 1.118 gives about 1,073 sq ft of actual sloped roof area. Using 960 ignores the slope, and the middle values understate the correction.2025 CA Residential Code (CRC) Chapter 8 (Roof-Ceiling Construction)