Getting clear on vapour barriers and underlays
A wall or roof underlay is very different from a vapour barrier. One lets moisture through and out of a building and the other doesn’t. Using the wrong one will trap moisture where you don’t want it.
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A wall or roof underlay is very different from a vapour barrier. One lets moisture through and out of a building and the other doesn’t. Using the wrong one will trap moisture where you don’t want it.
Older houses may have no building paper. Should it be installed during renovations, and how can this be done?
Underlay is an essential part of roofing installation, but there still appears to be some uncertainty about its use and installation.
The number of calls to the BRANZ Helpline suggest there is still a lot of confusion around when wind and air barriers are needed under the New Zealand Building Code.
Drained and vented cavities differ in width for masonry veneer and those behind other types of cladding. It’s important to understand these differences.
An aura of confusion often exists around air and vapour barriers. So, what are they, what do they do and when should we install one or the other?