A Look At Modified Bitumen Installation Methods

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. It features increased resistance to brittleness at cold temperatures, greater flow resistance at high temperatures, and increased elasticity can be achieved by blending synthetic rubberized polymers with asphalt. But did you know this interesting fact? It has a variety of installation methods. Take a look at four of the most common.

Hot-Asphalt Method
Modified bitumen systems can be installed in conventional hot asphalt, allowing the use of common ‘BUR’ equipment and application techniques. The most popular application method, RAMCON crews are utilizing this installation method every day.

Torch Applied Method
This application method is probably the second most common.
When this application is to be used, a manufacturer typically increases the thickness of modified bitumen on the backside of the roll and adds a thin plastic burn-off film. The additional bitumen and burn-off film melt under the application of a propane-fired torch, and they adhere the membrane to the roof insulation or substrate. Torch application does not require the use of hot asphalt, eliminating the need for an asphalt kettle. In areas where asphalt fumes become an issue or where asphalt cannot be transported to a roof, torch installation is a valuable option.

Cold-Adhesive Method
This third application option is gaining in popularity. In locations where hot asphalt cannot be used due to fumes or accessibility restrictions and where torch application might not be allowed or prudent, cold-adhesive application might be more appropriate. In such applications, the modified bitumen membrane is installed in the manufacturer’s cold adhesive.

Self-Adhesive Method
‘Peel and stick’ modified bitumen products have been available for more than 20 years. Most self-adhered membranes have been used on steep-slope roofing and as an underlayment for eaves and valleys. Manufacturers have now developed a membrane that has a very sticky surface on the back of the roll. A release paper is mated to this sticky side during manufacturing. When installing a self-adhering membrane, RAMCON technicians unroll the membrane, position it, peel off the backing, and then press it into place. The appeal of self-adhering roof membranes is related to concerns about asphalt fumes, torch safety and solvents in cold adhesives. Self-adhering membranes eliminate the need to lift asphalt, propane or adhesives to the roof, making it perhaps more suitable for hard-to-reach locations.