Vapor Barrier Vapor barriers are intended to prevent the moisture vapor entering crawlspaces
area. The vapor barrier is usually comprised of sheets of 6 millimeter
polyethylene (plastic). The sheets are laid in rows over the
soil. The edges of the sheets are overlapped and tapped to form a
continuous barrier that will trap the rising moisture. In most
locations, the vapor barrier is placed only over the soil and secured with
weights. In some regions, the vapor barrier is continuous over the
foundation wall and secured to the sill plate.
Crawlspace Vents Crawlspace vents prevent moisture vapor from accumulating in the
crawlspace by providing opening for the moisture to pass to the
exterior. Vents are required on new homes. The general
requirement is one square foot of
vent opening for 150 square feet of under-floor area.
