| Abstract | Roofs used to be simple. The structure had to be sufficiently sloped to allow water to run off. The material couId have included asphalt but it generally contained natural fibres which had some binder mixed in to hold it all together. There were few materials and mixtures. Putting a roof together was labour intensive but labour was inexpensive. Today, millions of square meters of residential and non-residential roofs are covered with water shedding or weatherproofing assemblies. The 1495 North American roofing marketwas approximately $22 billion Canadian ($18 billion in the US [I] and $4 billion in Canada). A roof assembly contains a roof system over a roof deck. The roof system is defined as having the elements which cover, protect and insulate the roof surface of a structure against the external environment. Roof systems vary from the traditional types (e.g., shingles for sloping roofs and built-up roofing (BUR) for flat roofs) to the nontraditional roofing materials (e.g., polymer-based single-pl y or modified bitumen). Theyalso vary in the method by which the covering has been put down. The conventional method is to have the covering (e.g., membrane) above the insulation and exposed to the environment. Alternatively, in a protected system, the covering is directly above the deck and be covered with the insulation. |
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