Are exposed nail heads on a roof a problem?
Short answer. Yes, unsealed exposed nail heads are a leak risk. A few are normal in specific places, such as the last ridge cap or some flashing, where they must be sealed; elsewhere, nails showing through or pushing up shingles mean high nailing, nail pops from decking movement, or shingles that slipped, and they should be properly re-fastened.
Where you might see them
- Last ridge cap: the final cap piece at the end of a ridge is face nailed. The heads should be covered with sealant.
- Flashing and vents: some vent flanges and flashings have exposed fasteners, which also need sealant or neoprene washers.
- Nail pops: nails backing out of the deck lift the shingle above, sometimes breaking through.
- High nailing or short courses: nails left exposed where a shingle was set wrong.
Why nails pop
- Decking expanding and contracting with heat and humidity.
- Nails that missed the rafter or truss and are held only by the sheathing.
- Underdriven nails left proud by the nail gun.
- Wet or soft decking that no longer grips.
Why it matters
Water runs down the nail shank into the deck. Exposed heads rust, and a raised nail can puncture the shingle above it as it heats and cools. Over time that means a stain on the ceiling and rot in the decking.
The right fix
- Pull the popped nail, or drive it flush if it is sound and in the right spot.
- Add a new nail nearby into solid wood, under the shingle above.
- Seal the old hole and any required exposed heads with roofing sealant.
- Replace any shingle the nail damaged.
A dab of caulk over a popped nail without re-fastening is temporary. See common causes of roof leaks and OSB vs plywood roof decking.