Common Roof Problems

Shingle deterioration: When shingles are old and worn out, they curl, split and lose their waterproofing effectiveness. Weakened shingles easily are blown off, torn or lifted by wind gusts. The end result is structural rot and interior damage.
A deteriorated roof system only gets worse with each day, and should therefore be repaired as soon as possible. 

Trees and leaves: Tree branches touching a roof will scratch and gouge roofing materials when the branches are blown by the wind. Falling branches from overhanging trees can damage, or even puncture, shingles and other roofing materials. Leaves on a roof system’s surface retain moisture and cause rot, and leaves in the gutters block drainage. 

Missing or torn shingles: The key to a roof system’s effectiveness is complete protection. When shingles are missing or torn off, a roof structure and home or building interior are vulnerable to water damage and rot. The problem is likely to spread-nearby shingles also are ripped easily or blown away. Missing or torn shingles should be replaced as soon as possible.

Flashing deterioration: Many apparent roof leaks really are flashing leaks. Without good, tight flashings around chimneys, vents, skylights and wall/roof junctions, water can enter a home or building and cause damage to walls, ceilings, insulation and electrical systems. Flashings should be checked as part of a biannual roof inspection and gutter cleaning.

Excerpted from the National Roofing Contractors Association
http://www.nrca.net/consumer/fyi.aspx