Flat roofs can be vulnerable to leaks, ponding, punctures and blistering which prevent proper water drainage from the roof. The result could mean costly damage to property, possessions and, even worse, severe injury to tenants or occupants.
Flat, built-up roofing is the most popular material used on low-slope roofs. A built-up roofing is composed of several layers of bitumen surfaces, and finished up with an aggregate layer or coating. The fabrics or layers used on built-up roofing are called ply sheets which incorporate a rigid insulation layer as part of the built-up roofing. These sheets are commonly made durable with fiberglass mats or organic mats, depending on their application. Ply sheets are generally produced in a standard size about 36 inches width.