Water in masonry walls creates numerous problems: freeze-thaw fractures, cracks form, efflorescence appears, wall stains, insulation failure, material swelling, wood warp, gypsum decay, metal corrosion, paint peels, mold grows, mildew forms, and odors reek. Much thought is given to warding off wind-driven rain by using wall drainage cavities, flashing, and weep holes; however, little attention is given to interstitial condensation that is often just as damaging.

This articles explains how an air barrier system can help alleviate this problem.