The Average Life of an Asphalt Shingle Roof

Travel down almost any residential street and you'll see multiple homes with asphalt shingle roofs. Asphalt shingles are the most common material for residential roofs in the United States, according to Cornell University's Department of Human Ecology. They are long-lasting, easily installed and relatively inexpensive. The shingles are composed of a mat core coated with several layers of asphalt. Granulated minerals contained in the final layer's topside protect shingles from ultraviolet rays.

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Light-colored shingles absorb less heat and last longer.

Life Span

Asphalt shingles generally last 15 to 30 years, according to U.S. Inspect. Their life span depends on several factors, including shingle weight, roof slope (to shed water), sun exposure, shingle color (light colors absorb less heat and last longer) and climate. How shingles are stacked in storage also matters. They should be protected from weather, stored flat and not be stacked higher than two pallets to prevent bottom pallets from becoming damaged by the weight of the top pallets.

Weather

Weather is a prime factor in shingle life span. U.S. Inspect notes that in hot climates, such as in Florida, asphalt shingles often deteriorate in 12 to 14 years. And, in northern states, such as Massachusetts, asphalt shingles on houses with high, sloped roofs and an eastern and or northern exposure can last 25 years. In light of regional climates, Roofhelp.com reports that the average life span for shingle roofs with a 20-year warranty in Phoenix, Arizona, is approximately 14 years, in Minneapolis, Minnesota, approximately 19.5 years and in Reading, Pennsylvania, approximately 20.8 years.

Warranties

Because of the many variables affecting shingles, warranties are not always a good indication of how long shingles actually last. However, shingles, which are available in different weights, colors and designs, are priced according to their warranty length, which is commonly 20, 25 and 30 years. Most asphalt shingles used on homes are three-tab shingles, which weigh approximately 240 pounds per 100 square feet of area and commonly have warranties of 15 or 20 years. Shingles with 30 or 40 year warranties are laminated shingles, also called architectural shingles, and are much more expensive than three-tab shingles, according to Cornell.

The Best Shingles

Shingle quality and durability depends on the quality of the materials used in their manufacturing, such as the asphalt and mat core, and the manufacturer's care in making shingles. To find the best shingles in your area, Cornell recommends asking building suppliers and roofers which manufacturers routinely produce high-quality shingles.

Deterioration

Shingle curling, cupping, splitting and loss of granules are signs that it's time for replacement. Loss of granules between shingle tabs is the strongest evidence that shingles are worn out, according to U.S. Inspect. Your options are to apply new shingles over the existing roof, if existing shingles are laying reasonably flat, if there is only one layer and the roof can hold the additional weight, or to remove existing shingles and then apply new ones.