Composition Roof: What It Is, Types and How Long It Lasts
Updated · By the Roof to Footing editors
A composition roof is a roof covered with composition shingles, which is the industry term for asphalt shingles. "Composition" refers to what they're made of: a fiberglass mat coated with asphalt and topped with ceramic-coated mineral granules. It's the most common roof in the United States, and when an insurance policy, home inspection or listing says "comp roof," this is what it means.
Types of composition shingles
| Type | Look | Typical lifespan | Notes |
|---|---|---|---|
| 3-tab | Flat, uniform rectangles | About 15 to 25 years | Lowest cost; being phased out by many makers |
| Architectural (dimensional, laminated) | Two layers for a shadowed, textured look | About 25 to 30 years | Today's standard; better wind ratings |
| Designer or luxury | Thick, made to look like slate or shake | 30 years and up | Heaviest and most expensive |
| Impact-resistant (Class 4) | Architectural or designer with a modified asphalt | Similar to architectural | Can lower insurance premiums in hail states |
Lifespans depend heavily on climate and attic ventilation. A roof in hot sun with a poorly vented attic ages faster than the same shingle up north.
Ratings worth checking
- Wind: look for ASTM D7158 Class H or D3161 Class F ratings in high-wind areas. Architectural shingles commonly carry ratings for 110 to 130 mph when installed with the maker's high-wind nailing pattern.
- Impact: UL 2218 Class 4 is the highest hail-impact rating. Many insurers in hail-prone states give a discount for it.
- Algae resistance: shingles with copper-containing granules resist the black streaks common in humid climates.
Minimum pitch
The International Residential Code (R905.2.2) allows asphalt shingles on slopes of 2/12 and steeper. From 2/12 up to 4/12, the code requires a double layer of underlayment. Below 2/12, shingles aren't allowed; use a membrane or standing seam metal instead. Not sure of your pitch? See roof pitch to degrees.
Composition vs. other roofs
- vs. metal: metal lasts two to three times longer and sheds snow, but costs more upfront and can dent in hail.
- vs. tile or slate: much lighter and cheaper, but shorter-lived.
- vs. wood shake: better fire rating and far less maintenance.
Parts of a composition roof
A full system includes the deck, underlayment, ice barrier at the eaves in cold climates, drip edge, starter strip, field shingles, flashing at walls and chimneys, vents, and hip and ridge cap shingles. Manufacturers' best warranties usually require using their accessories across the system. The ridge is a common weak spot; see our guide to the roof ridge cap.
Signs a comp roof is near the end
- Granules piling up in gutters and downspout splash areas
- Curling, cupping or cracked shingles
- Bald spots where the black asphalt shows
- Shingles lifting or missing after wind
- Daylight or stains on the attic side of the decking
One or two of these on an older roof is the time to start getting quotes, before leaks start.