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Thermal and moisture performance of a sealed cold-roof system with a vapor-permeable underlay

Ojanen, T.
2001
Proceedings Exterior Enevelopes of Whole Buildings VIII, Clearwater Beach, Florida, December 2-7

Ojanen, T., (2001), "Thermal and moisture performance of a sealed cold-roof system with a vapor-permeable underlay", Proceedings Exterior Enevelopes of Whole Buildings VIII, Clearwater Beach, Florida, December 2-7.
Abstract:
A sloped-roof structure, having only one ventilation airspace, is studied in this paper. In this cold-roof system, the underlay foil forms a nonventilated airsace above the thermal insulation, which improves the thermal performance of the roof. The internal moisture loads can be transported by diffusion through the highly vapor-permeable underlay to the ventilation cavity. The sealed underlay system works also as a additional resistance against air leakages. The thermal and moisture performance of the sealed and conventional roofs were studied in field experiments dones in a test building in southern Finland. different roof sections have been studied for three heating seasons. The experiments show that the sealed roofs have as good a moisture performance as conventional roofs. With similar air leakage paths and pressure differences, the sealed underlay systems could decrease the leakage airflow rate by 15% and the total heat losses through the ceiling by 23% when compared to a conventional roof.

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Author Information and Other Publications Notes
Ojanen, T.
Tiiomo Ojanen Senior research scientist VTT Building Technology, Finland.
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