Not all roof leaks occur due to missing shingles or holes in the roof. Sometimes water seeps in around the edges of a shingle, resulting in a leak. Fortunately, these types of leaks may only require a small shingle repair as opposed to a total roof replacement, depending on the severity of the problem.
1. Ice Dams
Ice dams are usually caused by clogged gutters. Snow melt flowing off the roof hits the clogged gutter and flows backward beneath the shingles near the edge of the roof. Some of that water freezes and a dam of ice begins to form underneath the shingle. When the ice melts, the water seeps into the house. Keeping gutters clear and ensuring water flows smoothly off the roof prevents ice dams.
2. Debris Buildup
A buildup of debris on the roof will cause issues much like an ice dam. Moss growth is a common culprit, particularly in damp or humid climates on shade roofs. Moss also traps moisture, which can degrade a shingle from the top down while water seeps beneath it. Other debris that cause similar issues are fallen twigs and leaves from overhead trees. Cleaning the roof periodically and replacing any shingles showing signs of degradation will prevent leaks.
3. Curling Edges
As shingles age, the edges can begin to curl up, a problem that is also known as cupping. Damage from hail strikes or weathering can exacerbate the problem. Water is able to seep underneath the curled edges and leak into the house. You can simply replace the cupped shingles if only a few are showing issues. For extensive cupping, you may need to replace the entire roof.
4. Edge Failure
Along the eaves of the roof, beneath the last row of shingles, should be a drip edge or gutter apron. This is a special strip of plastic or metal that wraps around the eaves of the roof and covers the decking boards under the shingles along the edge. It's designed to prevent water from blowing under the last course of shingles. If it is missing or damaged, then replacing it may solve the problem.
5. Loose Shingles
A single loose shingle compromises all the shingles abutting it, as water can now work under their edges. Although a missing shingle is the biggest issue, even those that have lost a nail or otherwise become loose can lead to leaks. Replacing or re-securing the problem shingle should solve the leak.
Contact a roofing contractor if you suspect that it is time for a shingle roof repair.