New 1/2″ plywood got put on over the old plank roof sheathing when I had my roof re-shingled. They were going for nailing into the rafters but I see a lot of misses. The line of nails just wonders off the rafter by an inch in places. Two questions: is this a serious issue and how do I trim the nails? They’re in the way of constructing insulation baffles and I don’t want to singe the shingle underlayment from below if I start cutting the nails with an angle grinder.
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Replies
It's annoying that roofers aren't more careful about nailing, but I've never seen it cause trouble. Cutting the nails off with an angle grinder won't cause enough heat to damage the shingles, but it would be better to just bend them over with a hammer, so they'll hold the new sheathing more securely.
Why are you "constructing insulation baffles?" Why not buy them? They don't cost much.
Not as annoying as when they BS you about it.
Why construct: irregularly spaced rafters, premade baffles seem flimsy, hard to seal, and don't leave a big enough vent channel. I see a lot of recommendations to build them out of plywood or rigid foam.
How are you supposed to not miss the rafters if they are irregularly spaced. Cut off the nails with an end cutter.
To be fair. Overlaying on top of existing makes it a bit harder to tell if you are hitting joist with nail gun. It’s to be expected in some areas. Everywhere on the other hand, is a lack of trying completely. Just bend them over, not worth the effort to cut them. While it might be a little unsightly it will be fine.
Bending the nails over sounds reasonable but won't that mean the planks will get destroyed if and when the plywood gets replaced? Or is that just so far in the future that it's moot?
Based on the limited areas I can see, 30% or more of the nails missed the rafter.
When you bend nails over it tends to loosen them. 30% misses isn't too spooky, not ideal but even the misses are held by a plank. I wouldn't bend them over.
If you need to cut off the shiners I'd try a good pair of nail nippers first, it may be easier than grinding. Only drawback is you'll have a little bit of nail still below the planks whereas with a grinder you can make them flush.
I think it’s a lot of work for something that doesn’t matter much at all. If you were to only have 1/2” ply or osb like most roofs you would have nails penetrating through the sheathing all over the place from shingling. Proper install on 1/2” ply actually calls for nails to go through the sheathing. If you bend the nails make sure to drive them sideways and not up, it will be fine. I don’t know how far they are penetrating, but I might consider not doing anything to them at all. Shiners in an attic space aren’t that big of a deal.