Why isn't plastic cement used on wood shingles?

Why isn't plastic cement used on wood shingles?

• A. It rusts
• B. Wood will expand and force the cement off
• C. It is too expensive
• D. It dries too quickly

Answer: (B)

Wood shingles change size with moisture and temperature. They swell and shrink, so any material used to seal or attach must be able to flex with that movement. Plastic cement is relatively rigid once it sets, so it can’t follow the wood’s expansion and contraction. As the wood moves, the cement bond fails and detaches, leading to cracks, lifting, and leaks. The other options don’t address this movement issue—rust only concerns metal, cost isn’t the primary failure mechanism, and drying speed isn’t the real problem here.

Wood shingles change size with moisture and temperature. They swell and shrink, so any material used to seal or attach must be able to flex with that movement. Plastic cement is relatively rigid once it sets, so it can’t follow the wood’s expansion and contraction. As the wood moves, the cement bond fails and detaches, leading to cracks, lifting, and leaks. The other options don’t address this movement issue—rust only concerns metal, cost isn’t the primary failure mechanism, and drying speed isn’t the real problem here.