Building scientists have come to realize that the practice of installing an interior vapor barrier is not appropriate to most climates in North America, and that, in fact, in many climates, putting plastic on the inside of a wall can cause serious problems.

That risk is becoming significant throughout the United States. In the past, summers in the northern tier of states generally weren’t warm and humid enough to create problems with interior vapor barriers. But over time, a majority of homeowners outside the southern tier, and even in the cooler regions of New England have gone using no air conditioning to using one window-rattler a couple of weeks a year to using central air conditioning for weeks on end. Adding air conditioning to buildings with interior vapor barriers poses a serious risk of moisture problems.

In this article in Remodeling's sister publication, JLC, Doug Horgan, vice president of Best Practices at D.C.-metro-based BOWA, Doug Horgan's first recommendation is to stop using Class 1 vapor barriers anywhere in the continental U.S. Learn why as Doug sleuths out the causes and solutions to a number of difficult condensation-related callbacks.

Read more.