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Controlling moisture under metal roofs

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Abstract
For several reasons, metal is more susceptible to condensation on the bottom side of the roofing panel (where it can cause unseen corrosion) than other forms of roof coverings; metal gains and loss heat rapidly, having both high conductance and emissivity; metal roofs are often used to retrofit an existing roof, which may contain moisture from previous leaks; metal is less forgiving for some elements of improper design, such as thermal bridging to the outside through subpurlinws and other steel support members within the attic cavity. Architects need to rethink attic ventilation when using metal panels.
Date
4/1998
Author(s)
Steve Hardy
Page(s)
26-32
Keyword(s)
attic ventilation; metal roof; thermal bridging; moisture; air flow; wind flow


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