Should roofing nails be exposed in the attic?
Why the nails come through
The residential code and shingle manufacturers call for roofing nails that penetrate at least 3/4 inch into the deck or through its full thickness, whichever is less. On the usual 7/16 inch OSB or 1/2 inch plywood, that means the tips stick out below the wood a little. A roof with no nail tips showing anywhere in the attic may have been nailed with fasteners that were too short, which can contribute to shingles blowing off.
What the tips tell you
- Clean, dry tips: normal.
- Rust stains around the tips: moisture has been condensing on them over time. Common causes are bath fans venting into the attic, air leaks from the house, and weak ventilation.
- Frost or ice on nail tips: on cold, clear north Georgia nights the nails are the coldest things in the attic and frost forms there first. When it melts, it drips onto insulation and can look exactly like a roof leak.
- Shiners: a nail that missed its mark and shows from below with no shingle tab holding anything. These sometimes show as raised bumps on the shingle surface too.
Are they a hazard?
Mostly to your head. Wear a hat and move carefully in the attic. There is no need to cut or clip the tips, and hammering on them from below can loosen shingles. If drips line up with nail rows after a cold night, look at ventilation and air sealing before blaming the roof covering. See roof ventilation basics and OSB vs plywood roof decking.