Asphalt. A bitumen-based substance that is used as a waterproofing agent for many roofing materials.
Blistering. Bubbles in a shingle caused by moisture that becomes trapped under or inside the material.
Blow-offs. Shingles that are torn off a roof by high winds.
Deck. The foundation of a roof onto which roofing materials are applied, typically made of plywood, wood boards, or planks.
Dry rot. Wood rot caused by fungi that are permitted to grow due to excessive moisture resulting from roof leaks or condensation.
Eaves. The first three feet of the lower edge of a roof, extending from the fascia to the outside wall.
Flashing. Pieces of metal or other material used to waterproof around projections through a roof, such as skylights, chimneys and vents, or along other vulnerable areas, such as roof valleys.
Granules. Tiny rocks which are coated with ceramic and fired, then applied to asphalt shingle mats as protection from the elements.
Low-slope roof. A roof in which the highest point is installed at a slope of 2:12 or less. Special installations must be used for low-slope roofs to permit proper drainage.
Steep-slope roof. A roof in which the highest point is installed at a slope higher than 4:12.
Underlayment. On a roof, underlayment acts as a secondary barrier against water leaks. For most manufacturers, underlayment is necessary for a valid warranty. It typically is manufactured as an asphalt-based roll.
Valley. The area where two roof slopes meet, creating a V shape. Roof valleys channel large amounts of water and are particularly vulnerable to leakage.
Ventilation. A roofing term which refers to the movement of air within an enclosed space, such as an attic.
Warranty. A written contract between a roofing manufacturer and the purchaser of roofing materials which outlines the liability the manufacturer will assume in the event of problems with the roofing system.