Condensation and moisture transport in cold roofs: effects of roof underlay

Emmanuel A. Essah, Chris H. Sanders, Paul H. Baker, Angela S. Kalagasidis

    Research output: Contribution to journalArticle

    Abstract

    Cold pitched roofs, with their form of construction situating insulation on a horizontal ceiling, are intrinsically vulnerable to condensation. This study reports the results derived from using a simulation package (Heat, Air and Moisture modelling tool, or HAM-Tools) to investigate the risk of condensation in cold pitched roofs in housing fitted with a vapour-permeable underlay (VPU) of known characteristics. In order to visualize the effect of the VPUs on moisture transfer, several scenarios were modelled, and compared with the results from a conventional bituminous felt with high resistance (200 MNs/g, Sd = 40 m). The results indicate that ventilation is essential in the roof to reduce condensation. However, a sensitivity analysis proved that reducing the overall tightness of the ceiling and using lower-resistance VPUs would help in controlling condensation formation in the roof.

    Original languageEnglish
    Pages (from-to)117-128
    Number of pages12
    JournalBuilding Research and Information
    Volume37
    Issue number2
    DOIs
    Publication statusPublished - 1 Jan 2009

    Keywords

    • condensation
    • cold pitched roofs
    • construction

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