In addition to our Research and Testing Facility we also have a Mobile Test Lab (MTL) that has been used for many years in different locations in Alaska. Today, the MTL is configured to test 9 different wall sections. We build the walls with variations in each section and test them outdoors during the winter while heating and humidifying the interior. We look at worst-case scenarios with humidity levels to determine if they will grow mold. We’ve asked questions about double barrier effect (water vapor passing through layers) which prevents the wall from drying out on the other side – condensing on materials and causing mold. You want to make sure water can’t condense inside your wall system and how much insulation do you need.
A general rule in Interior Alaska is at least 2/3 of the insulation should be outside the vapor barrier, and no more than 1/3 should be inside, and proper vapor barrier usage and installation is the key to success.
Should we be reliant on ventilation to keep humidity levels down instead of using different building practices?