A rotting roof is one where moisture has penetrated the decking beneath the shingles. This moisture then leads to wood rot in the decking, which can also cause the shingles to deteriorate.
1. Persistent Leaks
Leaks are the most common cause of rot on a roof. Missing or torn shingles, curled shingle edges, or actual roof punctures all lead to moisture leaking into the main roof decking and causing wood rot to take hold. Leaks don't just rot decking; the shingles themselves begin to deteriorate from the underside due to the trapped moisture. Promptly fixing leaks or replacing a badly damaged roof is the only way to prevent problems.
2. Flashing Pinholes
The aluminum flashing around chimneys and vents, or along roof valleys, can look fine from the ground, but it may actually contain small pinholes that allow water in. This problem occurs on older flashing that has begun to corrode. Once the moisture makes its way in, roof rot becomes a possibility. Inspect flashing annually for signs of damage, and then have it replaced or resealed before rot sets in.
3. Peeling Paint
Homes with wooden eaves are more prone to rot issues than those with vinyl or metal eaves. If the paint peels or fades too much, then moisture can seep into the wooden eaves. This causes the eaves to rot, along with anything in contact with — such as the edges of the roof decking. Paint eaves regularly so bare wood is always covered. Better yet, replace old wooden eaves with modern vinyl or metal options.
4. Poor Airflow
Poor airflow under the roof decking can result in rot from condensation on the underside of the decking boards, which is the attic ceiling. The cause is usually insufficient attic ventilation, which leads to moisture-laden air being caught in the attic. Every roof needs vents under the eaves and along the roof ridges. Large or complicated roofs may also need additional vents on the main roof plane.
5. Debris Buildup
Moss, fallen leaves, and clumps of small branches and twigs on a roof may only seem like an aesthetic issue. Unfortunately, this debris traps moisture against the shingles, which increases the chances of shingle rot and eventual leaks. Clean debris off the roof regularly, at least in fall and spring. It's also helpful to trim back trees so that air can flow better across the exterior roof surface.
Contact a roofing service like Coldstream Exteriors if you notice any issues with your roof, inside or out.