Question

True or false? The general rule-of-thumb for moisture protection at the building envelope is to provide vapor barrier shields on the side of the wall that’s warm in the winter.

Answer

True, with the following clarification: typically in colder climates, the vapor barrier is installed on the interior side of the wall system, and in hotter climates it is installed on the exterior side. However, in marine climates, certain dry climates, and some intermediate climates, the rule-of-thumb does not hold, and a variety of factors need to be considered in determining vapor protection placement.