A contemporary roof, regardless of shape or surface material, consists of a variety of components: wood framing, sheathing, underlayment, flashing, gutters and-of course-the shingles or other finished surface. The illustration shows how these materials go together to make a sound roof.
Roof deck is made up of sheathing and, in most cases, underlayment that's called roofing felt. The type of deck used depends on the finished roof material. Most call for solid plywood or oriented strand board (OSB) panel sheathing; wood shingles and some tile or metal roofs call for spaced board sheathing.
Roofing felt is sandwiched between the sheathing and the surface material on most roofs. This heavy, fibrous black paper saturated with asphalt helps repel any water that might find its way past the roofing material.
Roof surface material must be able to withstand wind, rain, snow, hail and sun. A wide variety of roof surface materials is available.
Flashing helps repel water wherever the roof surface is broken by dormers, intersecting roof planes and protrusions and along the roof's edges. Flashing is made from galvanized steel, aluminum or vinyl.