This roofing system is commonly known as a “tar and gravel” roof. Built-Up Roof (BUR) systems are composed of several layers of bitumen alternating with piles of reinforcing felts. These additional layers provide extra protection that perform well in extreme weather conditions. The surface of the roof is covered with a gravel application, a mineral cap sheet, or a weather resistant coating that protects the bitumen and felts.
Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation. The bitumen generally used in a built up roof system is coal tar, asphalt, or cold-applied adhesive. The coal tar or asphalt is heated in a kettle or tanker and then applied by mop or mechanical spreader.
A Built-Up Roofing System Consists Of:
BASE SHEET | Preventing cracks and splits in your roof starts with a sturdy foundation. A high-strength base sheet is first installed, specifically engineered to bond the membrane together. This base layer helps eliminate the possibility of fracturing or splitting later on, and acts as a flame-retardant protective shield.
FELTS OR FABRICS | Bitumen layers alternate with reinforcing felts. These felt layers provide insulation and flexibility to the bitumen, enhancing its performance in extreme weather conditions.
BITUMEN | Bitumen is an asphalt-based, adhesive-backed sheet that is extremely durable. In a built-up roofing system, multiple layers of bitumen are added.
SURFACING | There are a number of surfacing materials we work with, including crushed rock and gravel. Natural elements prevent deterioration of the bitumen and provide extra protection against harmful sun rays, heavy rain, high winds, and foot traffic.
Advantages of a BUR System:
The surfacing and materials used on BUR systems are varied and depend entirely on your project and its budget. Ballasted asphalt is being used more regularly than before because it can provide an excellent finished surface and the material is a better fire retardant agent.
Flame-Retardant Highly Durable Long-Lasting