Sun: Heat and ultraviolet rays cause
roofing materials to deteriorate over time.
Rain: When underneath roofing, water can work its way to the
deck and begin to cause rot.
Wind: High winds can lift the roof edges and force water
underneath.
Condensation: The buildup of relatively warm, moisture laden air
in a poorly ventilated attic promotes decay of the wood sheathing and
rafters.
Shingle deterioration: When shingles get
old and worn out, they curl, split, and lose their waterproofing
effectiveness and are more easily blown off, torn, or lifted by wind gusts.
Flashing deterioration: Many apparent roof
leaks are really flashing leaks around chimneys, vents, skylights, and
wall/roof junctions.
Moss can grow on wood shingles and shakes if they are kept moist
by poor sunlight conditions or bad drainage. Once it grows, moss holds
even more moisture to the roof surface, causing rot, and its roots
actually work their way into the wood.
Algae also grows in damp, shaded areas on wood or asphalt
shingle roof systems. Besides creating an ugly black-green stain, algae
can retain moisture, causing rot and deterioration.
Trees should be trim mined away from the
house to eliminate damp, shaded areas, and gutters should be kept clean to
ensure good drainage. Tree branches touching the roof will scratch and
gouge roofing materials as they are blow back and forth. Leaves retain
moisture and cause rot.
