Polymer-modified bitumen roof systems have been installed in the U.S. for more than three decades. During that time, polymer-modified sheet membranes traditionally have been mopped in hot asphalt or torch-applied; however, safety, health and environmental concerns associated with the use of hot asphalt and torch-applied membranes have led to more frequent use of alternative application methods. As a result, contractors increasingly are using cold adhesives to install polymer-modified bitumen membranes.
Defining cold adhesives
Cold adhesives first were used in Europe during the 1960s and were later introduced in the U.S. These early adhesives, typically used in re-cover and resaturant processes, have evolved into the current generation of cold adhesives that are used to install polymer-modified bitumen membranes.
Cold adhesives, as the name implies, are bitumen-based adhesives that do not require heat to be installed. Generally used to secure polymer-modified bitumen membranes to substrates, cold adhesives are composed of asphalt or coal tar that has been thinned, or cut back, with solvents or mineral spirits and blended with fillers and, sometimes, modifiers.