Modern roofing options are the result of eons of invention and experimentation. Some, such as slate and wood shakes, have remained virtually unchanged for centuries. Others, such as asphalt/fiberglass composites, lightweight concrete, and coated-metal tile, are products of the technological revolution. Each has slightly different durability, appearance, cost, and ease of application.
Although most modern roofs appear to be made almost entirely of shingles or tiles, they are actually waterproofing systems, made of components that work together. These systems include framing, sheathing, underlayment, flashing, and finish roofing.
Asphalt shingle roofs cap about 80% of American houses. They may be applied directly over older asphalt shingles, roll roofing, or roofing felt on solid sheathing. The asphalt/fiberglass varieties are more fire-resistant than the organic asphalt types.