Another benefit to covering the outside of a wall with foam is that it moves the dew point farther from the framing. Adding 2 in. of foam to the outside of a house in a cold climate is often enough to move the dew point somewhere inside the foam, and therefore a place where interior humidity can’t get to. This means that cavity insulation won’t get wet and mold won’t grow inside your walls.
Download the full article on how thermal bridging works from Fine Homebuilding magazine.
Plus, browse articles at GreenBuildingAdsvisor.com to learn a lot more about how insulation works and why it matters:
Insulating Roofs, Walls, and Floors