Contractor's General Building

1. Question 1 · Planning and Estimating

   A contractor is bidding a new two-story building that contains four apartments. Which part of Title 24 governs its structural and fire-safety design?
   • A.California Existing Building Code
   • B.California Building Code
   • C.California Residential Code
   • D.California Green Building Standards Code
   Show answer and explanation

   Answer: B. California Building Code

   The California Residential Code is limited to detached one- and two-family dwellings and townhouses not more than three stories above grade plane, with their accessory structures. A four-unit apartment building is a Group R-2 occupancy and is designed under the California Building Code. CALGreen adds green-building measures but does not set structural or fire-safety design.

2. Question 2 · Framing and Structural Components

   A gable roof has a 6-in-12 slope and a building span of 24 ft. Ignoring the ridge board thickness and any overhang, what is the line length of a common rafter?
   • A.26 ft 10 in.
   • B.18 ft
   • C.13 ft 5 in.
   • D.12 ft 4-1/2 in.
   Show answer and explanation

   Answer: C. 13 ft 5 in.

   Run = span ÷ 2 = 12 ft. Rise = 12 ft × 6/12 = 6 ft. Line length = √(12 × 12 + 6 × 6) = √180 = 13.42 ft, about 13 ft 5 in. Using the full 24 ft span as the run gives 26 ft 10 in., and simply adding rise to run gives 18 ft.

3. Question 3 · Core Trades

   A 50-amp, 240-volt branch circuit supplies an electric vehicle charger, which is a continuous load. What is the MAXIMUM load the charger may draw?
   • A.4,800 W
   • B.7,680 W
   • C.9,600 W
   • D.12,000 W
   Show answer and explanation

   Answer: C. 9,600 W

   A continuous load may not exceed 80% of the branch-circuit rating under the California Electrical Code. 50 A × 0.80 = 40 A; 40 A × 240 V = 9,600 W. Skipping the 80% step gives 12,000 W, applying it twice gives 7,680 W, and using 120 V gives 4,800 W.

4. Question 4 · Core Trades

   According to the California Building Code, what is the MINIMUM laboratory-tested sound transmission class (STC) rating for a wall separating two dwelling units?
   • A.STC 60
   • B.STC 45
   • C.STC 50
   • D.STC 55
   Show answer and explanation

   Answer: C. STC 50

   The California Building Code requires walls, partitions, and floor-ceiling assemblies that separate dwelling units from each other or from public areas to have an STC of at least 50 when laboratory tested, or 45 when field tested. Floor-ceiling assemblies must also meet an impact insulation class (IIC) of 50, or 45 if field tested.

5. Question 5 · Finish Trades

   According to the California Residential Code, what is the MAXIMUM height above the floor for the bottom of the clear opening of a bedroom emergency escape and rescue window?
   • A.36 in.
   • B.42 in.
   • C.44 in.
   • D.48 in.
   Show answer and explanation

   Answer: C. 44 in.

   The California Residential Code requires the bottom of the clear opening of an emergency escape and rescue opening to be not more than 44 in. above the floor. The opening must also meet minimum net clear area, height, and width dimensions, and it must be operable from the inside without keys or tools.

6. Question 6 · Planning and Estimating

   Under the California Residential Code, a retaining wall that supports no surcharge is exempt from a building permit when it is not over 4 ft high. How is that height measured?
   • A.Lower finished grade to top of wall
   • B.Bottom of footing to top of wall
   • C.Top of footing to top of wall
   • D.Upper finished grade to bottom of footing
   Show answer and explanation

   Answer: B. Bottom of footing to top of wall

   The permit exemption in the California Residential Code applies to retaining walls not over 4 ft in height measured from the bottom of the footing to the top of the wall, unless the wall supports a surcharge. A wall with 4 ft of exposed face is taller than that once the footing is counted, so it needs a permit.

7. Question 7 · Framing and Structural Components

   A 1,500 sq ft attic is vented at a ratio of 1 sq ft of net free area per 150 sq ft of attic. Half of the vent area is placed at the soffits. How much net free area is required at the soffits?
   • A.60 sq in.
   • B.360 sq in.
   • C.720 sq in.
   • D.1,440 sq in.
   Show answer and explanation

   Answer: C. 720 sq in.

   Total net free area = 1,500 ÷ 150 = 10 sq ft. Convert: 10 × 144 = 1,440 sq in. Half at the soffits = 720 sq in. Stopping at 1,440 sq in. ignores the split, using a 1-to-300 ratio gives 360 sq in., and multiplying square feet by 12 instead of 144 gives 60 sq in.

8. Question 8 · Core Trades

   An electrician measures 12 ohms across a 240-volt water heater element. How much power will the element draw?
   • A.57,600 W
   • B.4,800 W
   • C.2,880 W
   • D.1,200 W
   Show answer and explanation

   Answer: B. 4,800 W

   Current: I = E ÷ R = 240 V ÷ 12 ohms = 20 A. Power: P = E × I = 240 V × 20 A = 4,800 W. Multiplying volts by ohms gives 2,880, using 120 V gives 1,200, and squaring the voltage without dividing by the resistance gives 57,600.

9. Question 9 · Core Trades

   A dwelling's basement wall will retain earth on a site with a known high water table. According to the California Residential Code, what treatment is required on the exterior of the wall?
   • A.Waterproofing membrane up to finished grade
   • B.Polyethylene sheet on the interior face only
   • C.A cement parge coat without any membrane
   • D.Dampproofing coating up to finished grade
   Show answer and explanation

   Answer: A. Waterproofing membrane up to finished grade

   The California Residential Code requires dampproofing on foundation walls that retain earth and enclose interior space, but where a high water table or other severe soil-water condition is known to exist, the wall must be waterproofed up to finished grade. Dampproofing resists soil moisture only; it does not resist water under hydrostatic pressure.

10. Question 10 · Finish Trades

    According to the California Residential Code, the door between an attached garage and the dwelling must be equipped with which of the following?
    • A.Self-closing and self-latching hardware
    • B.Weatherstripping and a raised threshold
    • C.A keyed deadbolt and a door viewer
    • D.Panic hardware and a kick plate
    Show answer and explanation

    Answer: A. Self-closing and self-latching hardware

    The California Residential Code allows a 1-3/8 in. solid wood door, a 1-3/8 in. solid or honeycomb-core steel door, or a 20-minute fire-rated door between the garage and the dwelling. California also requires the door to be self-latching and equipped with a self-closing or automatic-closing device.

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