Friday, April 3, 2009

Life Expectancy of Roofs

How long should your roof last? The American Society of Home Inspectors provides the following estimates for the life expectancy of different roofing materials:
• Asphalt shingles: 15-30 years
• Wood shakes-shingles: 10-40 years
• Clay-cement tiles: 20+ years
• Slate: 30-100 years
• Metal roofs: 15-40+ years.

Rain isn't an ally either. Water will naturally take the path of least resistance. For this reason, minor roof leaks can result in extensive damage in various locations throughout a home. Aside from the obvious water-stained sagging ceiling, prolonged leakage will likely result in rot to framing members in the roof, ceiling, walls and floor.

High winds can lift the edges of shingles and force wind-driven rain and debris beneath them. Extremely high winds can tear random shingles from the roof, leaving the roof spotty or even bare in some locations. Properly anchored shingles will minimize this damage.

Snow, ice and hail also do their share to shorten the roof's life. Melting snow often will freeze over the roof's overhang where the surface is cooler creating an "ice dam" which blocks drainage to the gutter, and results in water backing up under the roofing material.

Gutters and downspouts also can freeze, preventing proper drainage. Eave-heating devices can prevent ice buildup. Check with your local hardware store or home center for the one that will work best for you.

Mildew, moss and lichen can accumulate on roofing materials if they remain damp as a result of poor drainage or little sunlight. Once it grows, moss holds moisture to the roof surface causing rot or poor watershed.

One of the best ways to rid the roof of moss and fungus is with a good power washing. (This may be best left to a roofing contractor or roof care professional.) Another way is to apply a solution of one quart of liquid chlorine bleach in a gallon of hot water to the affected areas, using a stiff nylon brush.

Prevent minor problems from becoming major repairs by inspecting your roof in the late fall and early spring. Using binoculars will give you a good view of the roof while keeping traffic on the roof to a minimum. Look for loose shingles or shakes, or, if you have a tile or slate roof, cracked or missing tile. On shingle roofs, look for curling, fraying and tears at the edges.