Flat roofing systems

by | Jul 18, 2016 | Roofing Contractor


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A flat roofing contractor in St. Louis is experienced in numerous types and styles of flat roof systems, the most common of which is BUR; Built up Roofing. Other types that are also used are single ply membrane, EDPM which is used on low slope roofs, Thermoplastic and modified bitumen.

Built up Roofing:

A BUR roof is often called a “tar and gravel roof” although it has been many years when tar was actually used, today it is bitumen.

A typical BUR system is composed of a number of layers of bitumen and fabric, the combination of the two materials results in a membrane. The number of layers of bitumen and fabric (plies) is what denotes the roof construction. Four layers are referred to as “four plies.” Depending on the spec and the flat roofing contractor in St. Louis, the base sheet is often mechanically fastened to the underlying structure.

The bitumen that is most often used during the construction of a BUR roof system is asphalt or adhesive which is applied cold. Asphalt must first be heated until it becomes a liquid; it is then spread over the fabric by mop or a mechanical device. Cold applied adhesives do not need to be heated prior to spreading.

BUR roofing is the most common roofing system

The materials used by a flat roofing contractor when constructing a BUR roof include aggregate which can be small pea-gravel, slag or mineral granules. The cap sheets are normally glass fiber and hot asphalt which is spread over the surface.

The roof is made from a number of layers of fabric and bitumen, the result is a water tight roofing system. Although pea-gravel has been the surface material that has been used for many years, it is often being given a final elastomeric or aluminum coating which helps to reflect the harmful effects of the sun. UV rays have a tendency to cause the roof to become brittle, which eventually results in a leak. A reflective coating helps to avoid this problem.

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