Sealing a Crawlspace
Close the vents and let a heavy-duty vapor barrier keep moisture, mold and radon out of the living space.
Synopsis: This article explains how unwanted moisture — in the form of water or water vapor — can enter a crawlspace with a dirt floor, and describes the materials and methods the author uses to prevent this from happening. A sidebar explains the problems that damp crawlspaces can cause in the home.
Dirt crawlspaces are never-ending sources of moisture. Even if the dirt’s surface is dry, digging down a little bit reveals moist earth. Moisture ruins houses by providing a hospitable environment for the fungi, mold and insects that destroy wood framing. Moisture in a crawlspace affects not only the floor system directly above it but also the entire house. Warm air in a heated building rises. As it rises, replacement air is sucked from the lowest part of a house. This natural air movement, called the stack effect, is how chimneys work. Consequently, whatever is in the air at the lowest…