When should you replace asphalt shingles?

How asphalt shingles wear out

A shingle is a fiberglass mat soaked in asphalt and coated with ceramic granules. The granules shield the asphalt from ultraviolet light. As the sun and heat work on the shingle, the asphalt slowly loses the oils that keep it flexible, granules loosen and wash into the gutters, and the newly exposed asphalt ages even faster. That is why wear speeds up in the later years.

The stages you can see

1. Early granule shedding. Some loose granules in the first year are normal.
2. Thinning color. Slopes look faded or blotchy as granule cover thins.
3. Blistering. Small raised bumps that pop and leave bare spots, often linked to a hot attic.
4. Curling. Edges turning up or middles lifting, which lets wind get underneath.
5. Cracking and brittleness. Shingles snap instead of bending and break off in storms.
6. Seal failure. Tabs no longer bonded to the course below lift and flap in wind.

Once stages 4 through 6 show on more than one slope, replacement is usually the better investment. Hail bruises, which look like random dark spots with missing granules, can reach that point overnight on any age of roof.

How replacement is done

A full replacement strips the old shingles to the deck, repairs decking, and installs new drip edge, leak barrier, underlayment, flashing, ventilation, shingles and caps, usually in a day on an average house. Why the Georgia climate is so hard on asphalt is explained in heat and humidity and roof life, and the attic's role in attic heat and shingles.