Nearly four-fifths of American homes have asphalt shingle roofs. The two basic types are composition and fiberglass-base shingles. Composition shingles have a core of organic “felt” made from wood and paper fibers. Fiberglass-base shingles have a core of manmade fiberglass matting.

Both composition and fiberglass-base shingles are soaked in asphalt, but the fiberglass base shingles are more fire- resistant than the organic ones. Asphalt shingles have mineral granules embedded in their surfaces to offer protection against wear and the sun’s ultraviolet radiation. When you find these granules washing away it’s a sign that you need to repair or replace your shingles.

Four types of asphalt shingles are manufactured: strip shingles, laminated shingles, interlocking shingles, and large individual shingles.

Strip shingles are the conventional type. They’re made in both standard and metric sizes. Those made for the American market are 12 inches wide by 36 inches long. Of these, “three tab” shingles are the most common. With these, a cutout distinguishes each tab, making it look like an individual 12-inch-wide shingle. Depending on how you align these tabs, you can create a variety of patterns of shadow and light on the roof.

Laminated shingles, also known as architectural or three-dimensional shingles, vary in the size, number, spacing, and thickness of the tabs. They have more character and visual depth than standard strip shingles.

Interlocking shingles, excellent for heavy-wind areas, are designed to fasten to one another.

Large individual shingles are generally used in specialty situations. Their shapes tend to be either hexagonal or rectangular and they don’t have tabs.

The portion of a shingle that shows is called “exposure,” and the lower edge is referred to as the “butt.” Shingles come in a variety of weights. Generally speaking, the heavier the shingles, the longer they last.

Choosing from the wide assortment of available colors, textures, patterns, and weights can be daunting. Most homeowners prefer premium-weight shingles, which may weigh 430 pounds per square (a 10-by-10-foot roof area), compared with standard shingles at about 230 pounds per square. Because premium-weight shingles are more three-dimensional, they do a better job of mimicking the texture of real wood shingles.