Modified Bitumen Roof Systems

The SBS Modifier

SBS modifier when combined with asphalt, produces rubberized properties. By adding 10%-15% SBS to the asphalt it is then able to be stretched six times its normal length and then can return to its original size once relaxed. This helps deal with the stresses of normal expansion and contraction of a roof. Reinforcements for SBS modified asphalt include fiberglass, polyester, or a combination of both. These membranes are most commonly applied with hot asphalt or cold adhesive. There are also self adhering SBS membranes, which contains an adhesive backing.

• Hot Asphalt application – Hot Asphalt is applied to the felts or substrate with the use of a machine or is physically mopped down and then the membrane is laid over the hot asphalt. The hot asphalt acts as the adhesive and allows the membrane to bond to the substrate.
• Cold Adhesive – The modified membrane is set in a cold process using specially formulated asphalt based adhesives as it is being applied.
• Self Adhered – The bottom surface of the membrane is covered with an adhesive and release paper. Once the paper is removed the adhesive allows the membrane to adhere to the substrate without the use of additional adhesives.

There are numerous surfacing options for APP and SBS modified roofs including factory applied mineral surfaces, gravel surfaces, smooth surfaces, and “cool roof” coatings, which are highly reflective coatings that can help save on cooling costs.

Modified Bitumen (MB) roofing is an asphalt-based, close cousin of the Built-up-Roof (BUR) designed for buildings with low-slope or “flat” roof structures. Engineered modified bitumen roofing membranes originated in Europe in the mid 1960′s and have been used successfully in the United States and Canada since approximately 1975.