The majority of homes in America use Composition Shingles. The shingles are made of a base (organic or fiberglass) that is saturated with asphalt and coated with minerals on one side to resist weathering. Composition roofs can be overlaid with a new roof if the initial roof is a single layer and in good condition. Shingles come in a wide variety of colors and depending on the rating of the shingle can last from 20-30 years.