How long should I expect my roof to last?
eventually wear out. How quickly that happens depends on several factors, including pitch of the roof, quality of materials and installation, level of attic/roof ventilation, and the climate in your area.
What causes a roof to wear out?
Several factors combine to affect roof deterioration
. These may include ultraviolet radiation from the sun; temperature extremes in your area; inadequate ventilation; exposure to wind, snow, ice and rain; and poor installation techniques, such as the use of stapes or too few nails in the shingles. Dark shingles may have a shorter service life than light-colored ones.
Splitting and cracking of the wood occurs naturally as part of the aging process, largely due to shrinking and swelling caused by moisture and subsequent drying.
Can an existing roof be covered with another?
prone to heavy snowfall, strong winds or hail, or when an existing roof is wood or tile, overlay may not be appropriate. In some locales, when a composition roof is replaced, the roofer may not be able to apply the new material directly on the old layer, depending on its condition.
Multiple roofing layers tend to decrease a roof’s resistance to hail. Check your local building codes before overlaying an existing roof covering. Some building codes and ordinances restrict the number of roofing layers a house may have.