Product Brochure
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When there is a pressure difference, air will find every penetration point into and out of a home, which is why proper
air sealing must create a continuous seal. Small gaps can add up. A typical 1970s home experiences enough air
leakage to equal an 11.4” diameter hole in the wall. Because of air leakage and its drying potential, those homes,
while not energy efficient, did not experience large-scale moisture issues. As we decrease air leakage, moisture vapor
management will become critical.
Equivalent hole size for typical leakage rates
Multi-Comfort House
Diameter: 3.3"
2012 IECC
Diameter: 7.5"
Minimal Renovation
Diameter: 9.5"
Typical 1970s Home
Diameter: 11.4"
Managing Moisture:
The Challenges of Vapor Retarder Solutions
The wall was built tight, so where does the water come from? How does it get in?
We all have to accept it at some point—there is no such thing as a waterproof wall. Moisture gets into a wall in many
different ways, but it can be narrowed down to two primary types of moisture flow:
Weather-resistive barriers have greatly improved the way we are able to manage bulk water infiltrating our walls, but
these systems are still prone to failure: joints can fail, seals can break and moisture finds its way into the wall. This is
why we must develop systems that will allow that excess moisture to escape the assembly.
Airborne moisture movement is tied to two key principles of building physics—diffusion and air leakage. Diffusion is
often noticed when an improperly installed vapor barrier begins showing signs of condensation on the material.
Air movement between the interior and exterior side of the wall can transport significantly higher amounts of water
vapor through the same wall. In colder climates during the heating season, 1/3 quart of airborne water passes through
a sheet of gypsum board via diffusion, whereas 30 quarts of water can be transported through a small hole in the wall.
It is for these reasons that air flow and moisture flow must be managed simultaneously.