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opinion on exposed roofing nails


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they have backed out on low slope with 11/2" rigid insulation onto 2x6" douglas fir t&groove deck. They haven't started leaking yet. 20 year old bur, old school like me. thx bb steve

Just so I understand the question. You have a "flat" roof with a 2x6 t&g decking, 1-1/2" of insulation board, and a ???-ply built-up roof with, I assume, no gravel and no granule-coated cap sheet. Is this correct?

Now some of the nails are backing out, up through the top layer like tiny little mushrooms wearing little black hats, right?

If this is happening uniformly across the entire deck, then the reason that this is happening is because the roofer used nails that are too short. The individual nail holes are easy to fix - just pull out the nail, press the end of a caulk tube against the hole, squirt it full of mastic, and embed a small bit of fiberglass mesh in mastic over the hole. The difficulty with this fix is that more nails will start to back out and it'll start to turn into a game of whack a mole.

Now, if it's just a few nails and they're in neat little lines, what you're seeing is the nails that hit the T&G section of the deck and never really bit into the wood on day one. There are a limited number of such nails and patching those holes is more realistic.

The larger problem is that tiny nail-shank-sized holes in a flat roof usually don't lead to visible leaks in the ceiling below. They just ooze small amounts of water -- enough to soak roof decking. Oftentimes, your first clue that the roof is leaking is when you discover a big rotten section of decking.

Aside from the backing-out nails, what's the condition of the rest of the roof covering? A nicely installed BUR in Orinda ought to last a good 30 years.

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