asphalt shingle
A shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather.
asphalt shingle: cheapest, most common roof covering in North America
An asphalt shingle is a flat rectangle of roofing material, typically 12 inches wide and 36 inches long, designed to overlap and nail down in courses across a pitched roof. The shingle itself consists of three layers: a base mat (historically felt, now usually fiberglass), a coat of hot asphalt that binds the mat and acts as a water barrier, and an exposed top layer of colored ceramic granules.
The granule coating serves two critical functions. It protects the asphalt from ultraviolet degradation, which would otherwise reduce shingle life from 20 to 25 years down to five or fewer. The granules also provide fire resistance, weather resistance, and aesthetic choice; manufacturers offer dozens of color blends by mixing granules of different hues and sizes. The underside of the shingle is often treated with a self-sealing strip of thermoplastic asphalt that adheres when nailed and warmed by sun, reducing wind uplift risk.
Variants and performance grades
Three-tab shingles, the budget standard, have a single sealant strip and an appearance of three separate shingles due to cutouts. Architectural (or laminate) shingles use multiple layers of base mat at different thicknesses, creating shadow lines and depth; these cost more but command longer warranties, typically 30 years. Premium brands with enhanced granule retention and impact resistance (rated for hail up to 1.5 inches in diameter) are also available. The weight of a bundle varies from 60 to 80 pounds depending on mat thickness and asphalt saturation.
Failure modes include granule loss (visible in gutters or downspouts after heavy rain), buckling or curling at edges (caused by moisture vapor rising through an unvented attic), blister formation (air pockets trapped during manufacturing), and seal-strip failure allowing water infiltration at overlaps. In hot climates, shingles soften and may slide downslope if the roof pitch is below 4:12. In cold climates, shingles become brittle and crack.
The economics of asphalt shingles dominate residential roofing in North America because labor costs are low, tools are simple, and material cost per square foot runs one-third to one-half that of metal, slate, or tile. A square (100 square feet) typically costs between 25 and 80 dollars depending on grade. Disposal is straightforward; old shingles go to landfill or, increasingly, are recycled into asphalt pavement or rubberized products.