On Aug 12, 10:43*am, DerbyDad03 wrote:
I have a basic side gable roof, consisting of a single layer of ~20
year old standard three-tab asphalt shingles over 3/4" T&G sheathing.
There are a number of nail pops that have lifted some tabs and some
that have actually punched through. There are a couple of spots where
the sheathing has gotten wet which I have dealt with by banging the
nails down and smearing roofing tar on the holes while I get some
estimates.
One contractor told me that while he is surprised that I have nail
pops in T&G sheathing, he is confident that he can pound the nails
back down and add a layer of architectural shingles, avoiding a tear
off.
My obvious concern is the possibility of *future* nail pops in other
locations. Even if he pounds the existing pops down, what is going to
prevent other nails from popping later? He also mentioned that nail
pops are not as big an issue with architectural singles due to their
thickness.
He is going to give me an estimate for both a tear off and a non-tear
off installation and leave the choice to me.
I’m interested in what others think about adding a second layer as
opposed to a complete tear off.
I’m also interested in what would occur if I opted for a complete tear
off. Would *all* of the old nails be removed or would they just be
pounded down anyway?
I'm not surprised that you're having nail pops with 3/4" T&G, and I'd
bet dollars to donuts that the roofer used his standard length roofing
nails (used on 1/2" plywood/OSB sheathing) and the nails aren't
protruding far enough through the sheathing. Some of the nail pops
are probably from the nails hitting the T&G gaps and not having enough
to bite into.
http://www.askthebuilder.com/487-Roo...t-Pop-Up.shtml
The remaining nails are often just swatted into the sheathing after a
tear-off. The new roofer is right that the heavier dimensional
shingles are not as susceptible to nail pops and that the nail pops
wouldn't telegraph through two layers. Dimensional shingles not being
perfectly flat also make it tougher to see minor imperfections such as
minor nail pops.
See if your new roofer would be willing to guarantee against the nail
pops telegraphing through for a couple or three years. I'm thinking
he won't, as it's your problem and you're making the choice, but you
never now.
R