C-39 Roofing exam questions, with answers
10 practice questions for the CSLB Roofing trade exam, each with the answer, a plain explanation and the source it rests on.
These are not real exam questions. CSLB does not release its test questions or answer keys, and nobody else has them. We write our own questions from the C-39 outline and the codes, standards and references CSLB lists for the exam. Each answer names its source so you can check it.
The C-39 exam has 5 sections. The questions below are grouped by section, with the share of the exam each one carries. Read the question, pick an answer, then open “Show the answer”. The other questions of the free test, scored section by section, are in the free 25-question C-39 test.
Planning and Estimating · 22% of the exam
Planning roof projects; estimating roof projects.
1. The roof over a homeowner's rear addition has a slope of 1 1/2:12, and the owner wants a covering other than a membrane. Which of these coverings does the California Residential Code permit at that slope?
- Wood shingles over 1x4 spaced sheathing
- Mineral-surfaced roll roofing over solid sheathing
- Asphalt shingles over two layers of felt underlayment
- Clay tile over two layers of underlayment
Show the answer
Answer: B. The code minimums are: roll roofing 1:12, asphalt shingles 2:12 (two underlayment layers from 2:12 up to under 4:12), clay or concrete tile 2 1/2:12 and wood shingles 3:12. At 1 1/2:12 only roll roofing qualifies; adding underlayment layers does not lower a covering's minimum slope.
2. Your bid for a 6:12 gable roof is $15,930. The plan (horizontal) area is 1,900 sq ft, and IKO's pitch factor table gives 1.118 for 6:12. The owner compares bids by price per square of actual roof area (1 square = 100 sq ft). What is your price per square, to the nearest dollar?
- $682
- $750
- $838
- $937
Show the answer
Answer: B. Actual roof area = plan area x pitch factor = 1,900 x 1.118 = 2,124.2 sq ft, or 21.24 squares; $15,930 / 21.24 = about $750 per square. $838 divides by the plan area (19 squares), $937 multiplies by the factor instead of dividing by it, and $682 adds 10% waste that is not part of the measured roof.
Job Site Preparation for Roof Projects · 13% of the exam
Protecting surroundings; correcting problems; tearing off existing roofing.
3. A large reroof starts with a week of tear-off, which will produce far more debris than the installation weeks that follow. What does Caltrans's solid waste management BMP (WM-5) advise for this demolition phase?
- Plan for extra containers and more frequent pickups
- Pile the overflow beside the bin until the next pickup
- Keep one container and have the crew compact each load
- Use bins without covers so the hauler can top them off
Show the answer
Answer: A. WM-5 tells the contractor to plan for additional containers and more frequent pickup during the demolition phase. It accepts only watertight dumpsters, and waste not in such dumpsters must be covered against wind and rain, so loose piles beside the bin or uncovered bins are the wrong approach.
4. Before a reroof in a mountain town where ice and snow last for weeks, you find a sagging 30-ft gutter with rusted and missing hangers, and you will rehang the whole gutter. HUD's inspection guide spaces gutter hangers no more than 3 ft apart, or no more than 18 in apart where ice and snow are long lasting. With a hanger at each end, what is the fewest hangers you can use?
- 10 hangers
- 11 hangers
- 20 hangers
- 21 hangers
Show the answer
Answer: D. Use the 18-in spacing because the snow is long lasting: 30 ft = 360 in, and 360 / 18 = 20 spaces, which need 21 hangers when there is one at each end. 20 forgets the hanger at the far end, and 11 (or 10) uses the 3-ft spacing meant for areas without long-lasting ice and snow.
Source: Section 2.8 Gutters and Downspouts, HUD Residential Rehabilitation Inspection Guide (2000)
Low-Slope Roof Projects · 17% of the exam
Installing flashings, ventilation and underlayment; installing various low-slope roof systems; repairing low-slope roof systems.
5. You are detailing emergency overflow for a home's flat roof enclosed by parapet walls, and the owner prefers scuppers through the parapet to a second set of drains. Which scupper design meets the California Residential Code?
- 2 times the primary drain size, at least 4 in high, inlet right at the low point
- 3 times the primary drain size, at least 6 in high, inlet 1 in above the low point
- Same size as the primary drains, at least 2 in high, inlet 4 in above the low point
- 3 times the primary drain size, at least 4 in high, inlet 2 in above the low point
Show the answer
Answer: D. The code lets you use overflow drains the same size as the primary drains, or overflow scuppers 3 times the size of the roof drains, at least 4 in high, with the inlet 2 in above the roof's low point. An inlet at the low point would act as a primary drain, and the other heights and multipliers are not in the code.
6. A building owner asks how single-ply membrane roofs are held in place. According to HUD's rehabilitation inspection guide, what are the three basic ways single-ply roofs are installed?
- Torch-applied, hot-mopped, or set in cold-process adhesive
- Heat-welded, seam-taped, or solvent-welded at the side laps
- Fully adhered, mechanically attached, or loose laid with ballast
- Spot-mopped, strip-mopped, or solid-mopped to the roof deck below
Show the answer
Answer: C. HUD lists three basic installation methods for single-ply roofs: fully adhered, mechanically attached, and loose laid with ballast. Torching and hot mopping are ways to apply modified bitumen and built-up roofs, and welding or taping describes how seams are joined, not how the sheet is held to the roof.
Source: Section 2.6 Low-Slope Roof Coverings, single-ply membrane roofing
Steep-Slope Roof Projects · 26% of the exam
Installing flashings, ventilation and underlayment; installing various steep-slope roof systems; repairing steep-slope roof systems.
7. You are checking how a new crew member's nailer is setting the nails in laminated asphalt shingles. According to ARMA's nailing bulletin, which nail is driven correctly?
- Straight, with the head sunk slightly into the shingle to lock it down
- Angled slightly up the roof, so the head grips more of the shingle mat
- Straight, with the head left just above the shingle so it can move
- Straight, with the whole head bearing tightly on the shingle surface
Show the answer
Answer: D. ARMA says nails go in so the entire head bears tightly against the shingle; they must not be underdriven, overdriven so they break or cut into the shingle, or driven crookedly. A sunk head cuts the shingle, a raised head can keep the shingle above from sealing, and an angled nail is a crooked nail.
8. On an older cedar shingle roof, many shingles have dried out, cracked and curled. According to HUD's rehabilitation inspection guide, when should the wood shingles be replaced rather than spot-repaired?
- When more than two-thirds show deterioration
- When more than one-half show deterioration
- When more than one-tenth show deterioration
- When more than one-third show deterioration
Show the answer
Answer: D. HUD says wood shingles and shakes dry, crack and curl as they age and should be replaced when more than one-third show signs of deterioration. Below that, damaged pieces can be repaired; waiting for half or two-thirds lets leaks and rot spread.
Safety · 22% of the exam
Personnel safety; job site safety; fall protection.
9. Your crew runs long compressed-air hoses from the compressor to the nailers on the roof. Besides hearing and eye protection, what does OSHA's roofing guide call for at the hose connections?
- A regulator at every coupling, set to the compressor's top pressure
- Whip checks or wire connections, so the hoses cannot separate
- Hose clamps every 10 ft, so the hose cannot slide off the roof
- Tape wrapped over each quick coupler, so it cannot be bumped loose
Show the answer
Answer: B. For compressed air the guide lists hearing and eye protection, a whip check or wire connections to prevent the hose from separating, and pressure adjusted to suit the tool. Tape is not a restraint, the pressure should match the tool rather than the compressor's maximum, and clamps along the hose do nothing at the couplings.
10. Your company will install tile on a new tract of homes. The builder's framing crews use roof anchors while they sheath the roofs. According to OSHA's fact sheet on installing tile roofs, what should you ask for at the preconstruction meeting?
- That the builder seal the anchor holes so water cannot reach the sheathing
- That the builder leave its roof anchors and fall gear in place after sheathing
- That the builder keep its crews on the roof until your own anchors are in place
- That the builder pull all roof anchors so the tile can lie flat on the roof deck
Show the answer
Answer: B. OSHA's tile-roof fact sheet says to ask the building contractor, at a preconstruction meeting or the first site meeting, to leave roof anchors or other fall protection equipment in place after sheathing is done. That way protection is ready before the roofers arrive, instead of each trade rigging its own.
Where to go from here
How the license works, from experience to fees: how to get a C-39 license. Everything about the course: the C-39 exam page.
Questions from our free C-39 test, written from CSLB License Examination Study Guide, Roofing (C-39), form 13E-39 (03-2026), for examinations scheduled on or after January 1, 2023. CSLB notes that the percentages are approximate. Reviewed 14 October 2026. Study guidance only; we are not affiliated with CSLB or PSI.