CSLB C-39 Roofing ContractorEstimating and PlanningMedium
A roofing crew is installing clay tiles on a roof that has a slope length of 28 feet from eave to ridge. The tile manufacturer specifies a 12-inch headlap and an average exposure of 10 inches per tile course. How many tile courses will be required for this slope length?
- A34 courses
- B28 courses
- C32 courses
- D30 courses
Show answer & explanationAnswer & explanation
Correct answer: A. 34 courses
The slope length is 28 feet, which is 28 * 12 = 336 inches. The first course typically requires the full tile length plus headlap, but for subsequent courses, the effective coverage is the exposure. However, when calculating courses for a slope length, you divide the total slope length by the exposure. 336 inches / 10 inches/course = 33.6 courses. Since you can't have a fraction of a course and must cover the entire length, round up to 34 courses.
Why the other options are wrong
- B. This would be if each course covered exactly 12 inches, not 10 inches.
- C. This is close but still an underestimation, possibly from miscalculation.
- D. This is an underestimation, likely from an incorrect calculation of exposure or rounding down.
Tile Course Count by Exposure
Determining the number of tile courses needed for a given roof slope length by dividing the total length by the tile's effective exposure per course.
- Exposure is the visible portion of a tile.
- Headlap is the portion covered by the next course.
- Always round up to ensure full coverage.
Memory trick: Slope Length divided by Exposure gives Courses, like slicing a loaf of bread.