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Q.A year ago, I removed an old wood shingle roof and replaced it with asphalt shingles. In many places, we replaced sections of the old board sheathing with new rough-sawn lumber. Now, the 8d common sheathing nails holding the new 6- to 12-inch-wide boards are popping up. Several nails have worked through the new shingles. What might be causing this problem, and how can it be corrected?

A.The problem was probably caused by using green rough-sawn lumber. Rough-sawn lumber is rarely dried. It will shrink during the first year or two, leaving nail heads sticking up from the surface of the boards. If the nails were not fully driven below the surface, this will be enough to cause a problem. The boards may also have cupped somewhat as they dried from the inside, pulling some of the nails, then flattened out as the outside dried with time, leaving the nail heads sticking up.

As far as repair is concerned, the nails can be driven down with a small punch, and the resulting hole in the shingle sealed with roofing cement. An alternative is to sandwich the top shingle between two putty knives — one slipped beneath the shingle and over the nail head and a second one on top of the shingle — and strike the top knife with a sharp hammer blow. This will re-drive the nail at least as far as the top of the second layer of shingle without damaging the weather face.

Next time, use dry lumber and ring-shank nails.