Q.How do I fasten cedar shingles to sidewalls covered with rigid foam?A.Paul Eldrenkamp, owner of Byggmeister, a custom remodeling firm in Newton, Mass., responds: That depends partly on the thickness of the foam. If it's 1 1/2 inches or less, we apply Cedar Breather over the taped foam to provide back venting, and fasten the shingles to the structural sheathing beneath with 2 1/2- or 3-inch stainless steel nails. That approach has worked fine in our area, but we aren't subject to big wind loads. If you're not comfortable using the surface of the foam as the drainage plane, you...

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