ASTM E96 -Standard Test Methods for Water Vapor Transmission of Materials
ASTM E96 states, “These test methods cover the determination of water vapor transmission (WVT) of materials through which the passage of water vapor may be of importance, such as paper, plastic films, other sheet materials, fiberboards, gypsum and plaster products, wood products and plastics.”
There are two terms to quantify water vapor transmission: permeability and permeance. Water vapor permeance is the Time rate of water vapor transmitted through a unit area of material Induced by unit vapor pressure difference between the two exposed surfaces of the material.
Permeance is used in performance evaluation, while permeability is a product of a Material.
There are two basic methods for measuring the permeance of a material such as fiberboard, gypsum, paper, plastic products, or plastic film: Desiccant method or the water method. Both methods utilize a test dish where the material under test is placed and sealed to the dish opening and then subjected to high vapor pressure or low vapor pressure.
Below you will find a video demonstration of the ASTM E96 testing process to determine permeability, performed at ICC NTA’s own A2LA Accredited Test Lab. This test method is used to determine the perm rating, or the amount of water vapor that will diffuse through a material in the presence of a vapor pressure difference. This test is often performed to ensure code compliance of building products such as moisture barriers and house wraps. You can learn more about Water Vapor testing by contacting us.