TO-98-13-5 -- Performance-Based Development of a Thermally Insulated Pitched Roof System ✓ Most Recent

Tiled and slated roofs in Western Europe are constructed using rafters, an underlay, counter-battens, and battens. Once the tiles or slates are fixed, thermal insulation, in most cases mineral fiber, is inserted between the rafters, a vapor and air barrier added, and the pitch finished with an internal lining. Although simple, construction nevertheless requires extra skill. Also, the hygrothermal performance is quite sensitive to poor workmanship.

This paper describes development of a new pitched roof, with the vapor retarder, thermal insulation, air retarder, and weatherproofing layer combined into one composite. This composite is fixed directly on the rafters. Performance requirements are adequate mechanical strength, high thermal resistance, good airtightness, correct moisture response, minimum thermal bridging, acceptable acoustical insulation, and acceptable fire resistance. The paper discusses the design process, with emphasis on the heat-, moisture-, and air-related aspects.

Units: SI