Nail Pops on Your Roof: What They Mean and When to Worry

What a nail pop is

Over time, roofing nails can back out of the sheathing a fraction of an inch at a time. When that happens, the nail head pushes up against the shingle above it and creates a small raised bump. That bump is a nail pop.

Left alone, the nail eventually tears through the shingle or breaks the seal, and rainwater runs straight down the nail shank into your attic.

Why nails back out

Two main reasons: wood movement and improper installation. Sheathing expands and contracts with temperature and humidity, and every cycle gives nails a tiny bit of room to walk. If a nail was driven slightly short, angled, or over-driven into a soft spot, it walks faster.

Older roofs with smooth-shank nails are more prone to popping than newer roofs installed with ring-shank nails, which grab the deck much more firmly.

Signs of active nail pops

Look at the roof from the ground with binoculars after a warm afternoon. Small raised bumps in a regular pattern across a slope are almost always nail pops. From inside the attic, you may also see shiny nail points sticking down further than they should.

How they get fixed

A single nail pop is a simple repair. The shingle is carefully lifted, the old nail pulled or driven flush, a new ring-shank nail set nearby, and the hole sealed with roofing cement. The shingle is re-bonded with sealant and re-set.

When nail pops are widespread, it is usually a sign the whole roof is entering its last few years and a full replacement should be planned.