GAF Timberline shingles tend to last about 15-25 years. They may not last as long as other types, including metal, copper, and even cedar, but they make up for it in other ways. Asphalt shingles are one of the most popular roofing products on the market today for a number of reasons. They’re affordable, durable, and visually-appealing according to many GAF Timberline shingle reviews by homeowners, contractors, and home inspectors.