Building knowledge and connections

Ribbit Resource: Reverse Vapor Drive

August 16, 2017

What Is 'Reverse Vapor Drive'?

'Reverse vapor drive' or 'inward solar vapor drive' is used to describe the inward vapor movement due to solar heating of an absorptive cladding such as brick veneer, stucco, and manufactured stone.

In the 1990's air-conditioned homes with poorly ventilated brick veneer were showing signs of condensation on the interior vapor barriers during the summer months. In the investigations that followed it was clear that the summer time condensation was in part due to reverse vapor drive.

A ventilated wall system-sometimes referred as a rain screen-provides a drainage and venting cavity for the wall system.

VaproShield's Installation Best Practices requires a rain screen or ventilated cladding design that 'vents off' the resulting vapor pressure when present. This practice prevents reverse vapor drive and allows effective drying in both directions of the wall system.

Review the complete Ribbit Resource on Reverse Vapor Drive on our website.


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