Built-Up Roofs

Built-Up Roofs In most instances, a good built up roof consisted of one ply of a heavy base felt followed by three to four plies of a lighter weight felt, all bonded together with saturated hot asphalt to form a thick waterproof membrane approximately 1/4" to 3/8" thick. These membranes could be installed over a dry felt nailed to a wooden deck or a rigid wood fiber insulation board.