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=92m interested in what others think about adding a second layer as opposed to a complete tear off.
I=92m 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?
Thanks!