The distance that adjacent shingles overlap horizontally is called what?

The distance that adjacent shingles overlap horizontally is called what?

• A. Sidelap
• B. Exposure
• C. Toplap
• D. Headlap

Answer: (A)

Sidelap is the horizontal overlap between adjacent shingles. As shingles are laid in courses, each piece covers part of the shingle beside it along the width, creating a side-to-side seam. This horizontal overlap helps seal the roof against wind-driven rain and keeps the pattern uniform across the roof. By contrast, exposure is the portion of the shingle that remains visible above the next course, and the vertical overlap between courses is typically called headlap (sometimes referred to as top lap). Understanding sidelap ensures proper weatherproofing and roof appearance.

Sidelap is the horizontal overlap between adjacent shingles. As shingles are laid in courses, each piece covers part of the shingle beside it along the width, creating a side-to-side seam. This horizontal overlap helps seal the roof against wind-driven rain and keeps the pattern uniform across the roof. By contrast, exposure is the portion of the shingle that remains visible above the next course, and the vertical overlap between courses is typically called headlap (sometimes referred to as top lap). Understanding sidelap ensures proper weatherproofing and roof appearance.