CSLB C-39 Roofing ContractorEstimating and PlanningEasy
A contractor is installing standard three-tab asphalt shingles with a 5-inch weather exposure on a roof section with a slope length of 30 feet from eave to ridge. How many courses of shingles are required to cover this section?
- A72 courses
- B66 courses
- C78 courses
- D60 courses
Show answer & explanationAnswer & explanation
Correct answer: A. 72 courses
Convert the 30-foot slope length to inches: 30 × 12 = 360 inches. Divide by the 5-inch exposure per course: 360 ÷ 5 = 72 courses.
Why the other options are wrong
- B. Results from an incorrect conversion of feet to inches.
- C. Overestimates by using too small an exposure value.
- D. Would require a 6-inch exposure, not the given 5-inch exposure.
Shingle Course Exposure
The exposed portion of each shingle course determines how many courses are needed to cover a given slope length.
- Convert slope length from feet to inches before dividing.
- Standard 3-tab exposure is typically 5 inches.
- Courses = slope length (inches) ÷ exposure (inches).
Memory trick: Feet to inches, then divide by exposure inches.