Which of the following is not a suitable decking substrate for an asphalt shingle roof?

Which of the following is not a suitable decking substrate for an asphalt shingle roof?

• A. 1" x 6" solid
• B. 1" x 6" spaced
• C. plywood
• D. solid wood planking

Answer: (B)

A shingle roof needs a solid, continuous deck to provide a stable nail line and uniform support for every shingle. When the decking has gaps, like spaced 1x6 boards, the surface isn’t continuous enough to nail into properly and to support the shingles evenly. Those gaps can cause shingles to lie unevenly, allow water or moisture to reach underlayment or sheathing, and make the deck less resistant to wind uplift. Tight, continuous surfaces—such as solid 1x6 boards laid close together, plywood, or solid wood planking—give the shingle system the stable base it requires.

A shingle roof needs a solid, continuous deck to provide a stable nail line and uniform support for every shingle. When the decking has gaps, like spaced 1x6 boards, the surface isn’t continuous enough to nail into properly and to support the shingles evenly. Those gaps can cause shingles to lie unevenly, allow water or moisture to reach underlayment or sheathing, and make the deck less resistant to wind uplift. Tight, continuous surfaces—such as solid 1x6 boards laid close together, plywood, or solid wood planking—give the shingle system the stable base it requires.