In CertainTeed jargon, head lap refers to the entire upper portion of a shingle covered by the succeeding course after installation — about how many inches for 12" x 36" strip shingles?

• A. About 5 inches.
• B. About 3 inches.
• C. About 7 inches.
• D. About 9 inches.

Answer: (C)

Head lap is the portion of a shingle that gets covered by the shingle above it after installation. For 12" x 36" strip shingles, CertainTeed specifies about seven inches of head lap. This amount provides enough overlap to seal the seam against wind and rain, helps hide the underlying fasteners, and keeps the courses staggered for a uniform, weather-resistant installation. If the overlap were smaller, leaks and wind uplift could be more likely; if it were larger, you’d waste material and affect appearance. So seven inches is the recommended balance for this shingle size.