| The best way to accomplish this is by selecting below-slab moisture protection of extremely low permeance. |
| Where a single product provides all these functions, there is no risk of trapping moisture between two functional barriers with low water vapour permeance. |
| One board was a low air and vapour permeance material while the other was a high air and vapour permeance material. |
| Temperature is the predominant physical factor influencing the permeance of a barrier. |
| Water vapor permeance is a measure of how quickly water vapor is transmitted through a material and can be determined according to the ASTM E96 Standard Test Method for Water Vapor Transmission of Materials. |
| While the permeance of membranes is typically constant for ideal gases, this behavior changes for non-ideal gases and vapors. |
