Vapor Retarders and Vapor Barriers
What is the difference between a vapor barrier and a vapor retarder?
A vapor barrier stops more vapor transmission than a vapor retarder. A vapor barrier is usually defined as a layer with a permeance rating of 0.1 perm or less, while a vapor retarder is usually defined as a layer with permeance greater than 0.1 perm but less than or equal to 1 perm. Synergy’s North American partner, W.R Meadows, beats the lowest in the industry with 0.002 perms.