CSLB C-39 Roofing Exam Practice
Question and Correct Answers –
New Update 2026/2027
Section 1 — Planning and Estimating
Question 1. Calculating roofing squares
A rectangular roof section measures 30 feet long and 40 feet wide. Ignoring slope and
waste, how many roofing squares are required? One roofing square covers 100 square feet.
A. 8 squares
B. 10 squares
C. 12 squares
D. 14 squares
Correct answer: C. 12 squares
Detailed rationale: Calculate the area: \(30 \times 40 = 1{,}200\) square feet. Divide by 100
square feet per roofing square: \(1{,}200 \div 100 = 12\) squares. This is the flat-plan area
only. Actual roof surface area may be greater on a sloped roof, and the material estimate
should account for waste and the manufacturer's coverage specifications.
Question 2. Estimating material waste
A roof has a measured surface area of 2,400 square feet. The contractor estimates a 10%
allowance for cutting and waste. What total area should be used for the preliminary
material estimate?
,A. 2,400 square feet
B. 2,500 square feet
C. 2,640 square feet
D. 2,800 square feet
Correct answer: C. 2,640 square feet
Detailed rationale: Ten percent of 2,400 is \(2,400 \times 0.10 = 240\) square feet. Add the
allowance to the measured area: \(2,400 + 240 = 2,640\) square feet. The appropriate waste
allowance varies with roof geometry, valleys, penetrations, material type, and installation
pattern.
Question 3. Roof pitch
A roof rises 6 inches vertically for every 12 inches of horizontal run. What is its pitch?
A. 3:12
B. 6:12
C. 12:6
D. 18:12
Correct answer: B. 6:12
Detailed rationale: Roof pitch is commonly expressed as vertical rise per 12 inches of
horizontal run. A rise of 6 inches over a 12-inch run is a 6:12 pitch. Pitch affects material
selection, installation methods, drainage, and safety requirements. It is not the same as
the roof's angle in degrees.
Question 4. Labor estimating
A roofing job is estimated to require 96 labor-hours. A crew of four worḳers can each
contribute six productive hours per day. How many worḳing days are estimated?
, A. 2 days
B. 3 days
C. 4 days
D. 6 days
Correct answer: C. 4 days
Detailed rationale: The crew's daily production is \(4 \times 6 = 24\) labor-hours. Dividing 96
labor-hours by 24 labor-hours per day gives \(96 \div 24 = 4\) days. Therefore, the correct
answer is C. 4 days.
Question 5. Roofing material selection
Which factor is most important when determining whether a particular roofing material is
suitable for a project?
A. The material's color alone
B. The contractor's personal preference alone
C. Roof slope, structural capacity, climate exposure, manufacturer requirements, and
applicable codes
D. Whether the material is the least expensive item available
Correct answer: C. Roof slope, structural capacity, climate exposure, manufacturer
requirements, and applicable codes
Detailed rationale: Roofing materials have different limitations and performance
characteristics. For example, some systems require a minimum slope, some impose
structural loading considerations, and others have special requirements for wind, fire, or
moisture exposure. Material selection must account for the entire roofing assembly and
applicable regulations, not just appearance or purchase price.
Question and Correct Answers –
New Update 2026/2027
Section 1 — Planning and Estimating
Question 1. Calculating roofing squares
A rectangular roof section measures 30 feet long and 40 feet wide. Ignoring slope and
waste, how many roofing squares are required? One roofing square covers 100 square feet.
A. 8 squares
B. 10 squares
C. 12 squares
D. 14 squares
Correct answer: C. 12 squares
Detailed rationale: Calculate the area: \(30 \times 40 = 1{,}200\) square feet. Divide by 100
square feet per roofing square: \(1{,}200 \div 100 = 12\) squares. This is the flat-plan area
only. Actual roof surface area may be greater on a sloped roof, and the material estimate
should account for waste and the manufacturer's coverage specifications.
Question 2. Estimating material waste
A roof has a measured surface area of 2,400 square feet. The contractor estimates a 10%
allowance for cutting and waste. What total area should be used for the preliminary
material estimate?
,A. 2,400 square feet
B. 2,500 square feet
C. 2,640 square feet
D. 2,800 square feet
Correct answer: C. 2,640 square feet
Detailed rationale: Ten percent of 2,400 is \(2,400 \times 0.10 = 240\) square feet. Add the
allowance to the measured area: \(2,400 + 240 = 2,640\) square feet. The appropriate waste
allowance varies with roof geometry, valleys, penetrations, material type, and installation
pattern.
Question 3. Roof pitch
A roof rises 6 inches vertically for every 12 inches of horizontal run. What is its pitch?
A. 3:12
B. 6:12
C. 12:6
D. 18:12
Correct answer: B. 6:12
Detailed rationale: Roof pitch is commonly expressed as vertical rise per 12 inches of
horizontal run. A rise of 6 inches over a 12-inch run is a 6:12 pitch. Pitch affects material
selection, installation methods, drainage, and safety requirements. It is not the same as
the roof's angle in degrees.
Question 4. Labor estimating
A roofing job is estimated to require 96 labor-hours. A crew of four worḳers can each
contribute six productive hours per day. How many worḳing days are estimated?
, A. 2 days
B. 3 days
C. 4 days
D. 6 days
Correct answer: C. 4 days
Detailed rationale: The crew's daily production is \(4 \times 6 = 24\) labor-hours. Dividing 96
labor-hours by 24 labor-hours per day gives \(96 \div 24 = 4\) days. Therefore, the correct
answer is C. 4 days.
Question 5. Roofing material selection
Which factor is most important when determining whether a particular roofing material is
suitable for a project?
A. The material's color alone
B. The contractor's personal preference alone
C. Roof slope, structural capacity, climate exposure, manufacturer requirements, and
applicable codes
D. Whether the material is the least expensive item available
Correct answer: C. Roof slope, structural capacity, climate exposure, manufacturer
requirements, and applicable codes
Detailed rationale: Roofing materials have different limitations and performance
characteristics. For example, some systems require a minimum slope, some impose
structural loading considerations, and others have special requirements for wind, fire, or
moisture exposure. Material selection must account for the entire roofing assembly and
applicable regulations, not just appearance or purchase price.
