With slate roofing, the overlap from one course to the next should cover nail holes of the lower course by at least:

With slate roofing, the overlap from one course to the next should cover nail holes of the lower course by at least:

• A. 1 inch
• B. 2 inches
• C. 3 inches
• D. 4 inches

Answer: (C)

Slate roofing relies on each new course overlapping the nails of the course below, so water and wind don’t have a path to the nail heads. The overlap must be large enough to fully cover those nail holes. The minimum overlap is three inches, which ensures the upper slate hides the lower course’s nails and directs water over the joint rather than into the fasteners. If the overlap were smaller, water could reach the nail heads and potentially leak or allow wind to pry the slate loose; larger overlaps are acceptable and sometimes required in high-wind areas or with specific slate sizes, but three inches is the standard minimum.

Slate roofing relies on each new course overlapping the nails of the course below, so water and wind don’t have a path to the nail heads. The overlap must be large enough to fully cover those nail holes. The minimum overlap is three inches, which ensures the upper slate hides the lower course’s nails and directs water over the joint rather than into the fasteners. If the overlap were smaller, water could reach the nail heads and potentially leak or allow wind to pry the slate loose; larger overlaps are acceptable and sometimes required in high-wind areas or with specific slate sizes, but three inches is the standard minimum.