When a roofer installs shingles on a roof, they usually make sure that the layer of shingles on top covers the nails on the lower sheet of shingles. So when the roofing project is complete, you should not see any nail heads. As the roof ages, however, nail heads can become exposed, which will put your roof at risk for leaks and other issues. Here's a closer look at how nail heads become exposed and why this is such a problem.

How do nail heads become exposed?

Usually, nail heads become exposed when your roof loses some shingle tabs in a storm or high winds. At first, you're probably not too concerned when you see a single tab or a few tabs missing, since there are still multiple layers of shingles underneath it. However, if the missing shingle reveals the nails put through the lower layer of shingles, there lies the problem.

Exposed nail heads can also arise from poorly performed roof repairs. When repairs are made, you really should take the time to bury the new shingles under the old, hiding the nail heads. In an effort to save time, however, people sometimes just nail new shingles over top of the old ones. This leaves the nail heads in the new shingles exposed.

Why are exposed nail heads bad?

Exposed nail heads can make your roof look less attractive,  but that's not the main reason why they are bad. Water can seep around the edge of the nails, working its way through your roof. The resulting leak may just be a trickle, but it can cause mold growth in your attic, water damage to insulation, and so forth. If you have had water in your attic but have had trouble finding the source of the moisture, it could be coming from an exposed nail head or two.

How can you address exposed nail heads?

The easiest way to deal with exposed nail heads is to wait until a dry day, and then put a glob of roofing cement over each nail head. The cement will bind between the shingle and the nail head, stopping water from seeping in. If your roof is damaged, and that is why the nail heads are exposed, you will want to have a roofing company come make more extensive repairs. Numerous exposed nail heads and missing shingles usually indicate that a roof has reached the end of its lifespan.