Air and vapour barrier arrangements for public buildings in the Northwest Territories, Canada

A roof retrofit program instituted for replacing the roofs of buildings in the Northwest Territories in Canada failed, owing to the buildup of asphalt roofing membranes in such roofs. After a careful study, there seemed to be little point in replacing the existing roofing membrane with the same materials. The search for a less problematic and more durable solution led to a change in the choice of materials and a system which represents a shift in thinking with respect to the significance, functions, and positions of the air/vapor barrier, of the insulation, and of the water-shedding membrane.