- 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.