Vapor Retarders
Vapor retarders are an integral component of any metal building
insulation system. The vapor retarder, in combination with
the correct insulation value for your regional weather conditions
and appropriate airflow is your first line of defense against
condensation. Vapor retarders key features are classified
by permeance, strength and light reflectivity.
"Permeance" or "perm" rating is a measure used
to quantify the rate of water vapor transfer through the facing
into the fiberglass and onto the metal skin of the building.
There are three basic perm levels offered by the facing suppliers:
.02, .09 and 1.0. Lower perm facings reduce the amount of
moisture entering the fiberglass, which helps to save energy,
reduce condensation and avoid future moisture related problems.
Theoretically*, in a 50,000 sq. ft. building, a .02 perm
facing will allow 1 gallon of water to pass through the facing
in one week. This compares to 5 gallons for a facing with
a .09 per, and 50 gallons for a facing with a 1.0 perm rating.
The strength on a vapor retarder is measured by the
following tests:
- Mullen - a measure of the force required for a blunt object to rapture the facing.
- Beach - a measure of the energy required for a sharp object to puncture the facing.
- Tensile - resistance to breaking while being pulled.
Below is an overview of our product lines:
*Test conditions: ASTM E96 procedure A-73° F and 50% RH on one side of the vapor retarder, and 73° F and 0% RH on the other side.
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