Built-up roofing consists of multiple layers of modified bitumen roofing and reinforcing membrane. It is the oldest and most common type of roof system. Built-up roofs, or BURs, are generally referred to as tar and gravel roofs.
BURs have three components: a waterproofing layer, a reinforcing layer and a surfacing layer, and can be installed using asphalt, coal tar, or cold-applied adhesive. Possible surfacings include aggregate, mineral surfaced or glass fiber cap sheets, hot asphalt, or elastomeric or aluminum coatings.
Service life varies from location, but can generally range from 15-25 years
A roofing square is equal to 100 square feet. The “slope” or “pitch” refers to the incline on the roof. Generally interpreted as the number of inches rise