Built-Up Roofing System Options

Graveled Surface
This system consists of a traditional roof mat, comprised of four layers of asphalt moppings and four layers of reinforcing felts. There are two grades of reinforcing felts—the standard type IV felt plies can be warranted up to 12 years. Premium type VI felts have a higher tensive strength, and therefore can be warranted up to 20 years. Modified bitumen base flashings are installed at perimeter and curb flashings, adding additional redundancy of crucial locations. The roof is then flooded with hot asphalt and roofing gravel is broadcast into the asphalt providing a protective surface for both traffic and ultra violet rays from the sun.

Modified Bitumen Cap Sheet (Mop in place)
Similar in construction to a built-up roof, the roof mat is comprised of multiple layers of asphalt and reinforcing felts, either type IV or type VI, depending on warranty periods. The main difference is in lieu of the graveling process, the entire roof system including the field and base flashing locations are covered by a layer of 160 mil mopped in place modified bitumen. This system works well for mid to high-rise buildings where access is difficult.