ABSTRACT

Built-up bituminous waterproofing membranes have been fading in popularity for several decades, supplanted by a plethora of new materials and systems. Built-up waterproofing membranes are semi-flexible laminates, comprising alternating layers of normally hot-applied bitumen and felt reinforcement. Along with their counterpart built-up roofing (BUR) membranes on low-sloped roofs, built-up membranes are the oldest waterproofing system, introduced in the nineteenth century. Built-up membranes share a minimal and decreasing part of the waterproofing market because of the relentless march of air-pollution regulations. On projects complicated by the aforementioned factors, built-up membranes become impracticable; their advantages outweighed by their disadvantages. Built-up waterproofing membranes and liquid-applied membranes are at opposite ends of the spectrum. Waterproofing bitumens are the same basic materials used for built-up roof membranes but restricted to unblown asphalts in the lower viscosity range. Built-up waterproofing membranes made from these asphalts can suffer severely shortened service lives.