Description

Roof underlays constitute the second line of defence of the roof envelope and they are an essential element of the interstitial moisture management strategy in roof spaces.

This report, which is the second in a series of reports, describes some of the experimental results obtained during the study of roof underlays aimed at investigating which of their physical properties are required to fulfil the task of managing moisture in interstices.

The report describes the physical properties of a range of roof underlays and other building wraps, the layout and instrumentation of a test house built to test them and some of the experimental results obtained.

Two phenomena which could give rise to interstitial condensation are investigated: condensation generated by night sky radiactive cooling and condensation drive by solar radiation.