Hot Asphalt Roof Applications

Hot asphalt roof applications generate mixtures of solvents and high-boiling organic compounds that can permeate into indoor air, particularly if air intakes are located on roof tops. These vapor mixtures, even when present in very low concentrations, can produce eye and upper respiratory tract irritation in building occupants. 39  

---

Lynch RM, Kipen H. Building-related illness and employee lost time following application of hot asphalt roof A call for prevention. Toxicol Ind Health 1998 14(6) 857-68. 

Typical application of a BUR would be to mop or apply asphalt to a substrate to approximately 1.1 kg/m2 (23 lbs/100 ft2), or the thickness of a dime. A ply sheet would then be unrolled into the hot asphalt. Additional ply are then mopped in, with each layer offset so that the roof has three or four plies of felt over the entire roof. The amount of offset is calculated by the formula, offset = 34 in. (86.4 cm)/number of plies. Manufacturers of plies print laying lines on the felts at the correct locations to assist in laying up the roof with the correct offset. 

SBS membrane systems are generally installed in hot asphalt but can be installed using a torch like APP products or in some cold application cement systems. Like APP systems, they are generally installed in multiple layers. The undedayment layers are generally standard BUR felts or basesheets. SBS membrane sheets can also be formulated to be self-adhering. These products are no longer used in membrane applications but are used as ice and water dam materials on the eaves under shingle roofs in cold climates. 

The application of MBRs vary with the system. SBS roof systems have been developed to be applied with hot asphalt, heat or rubber-based adhesives. APP roof systems are commonly applied using heat, but may be applied by cold adhesives such as epoxies or acrylates. 

Over the years, multilayers of tar-based waterproofers replaced the hot asphalt used in roofing. In early 1900, asphalt became available from petroleum refining, and it was followed by oxidized bitumen interlaid with roofing felt and then alternated with a mineral base sheet, l" Asphalt-based materials are used extensively as binders, sealants, and waterproof coatings in diverse applications because of their low cost, inherent cohesive nature, weather-resistant properties, and ease of processing in the molten state. 

---