Air-gap membranes have been
used in Europe and Canada for
years. Manufacturers claim that
combined with a good footing
drain the membrane
provides
dry, odor-free
basement living space. I recently had the
opportunity to install one of these products
on a new foundation in northern
Vermont. The membrane, called Delta-
MS, is made by Cosella D¨orken, a German
company with North American offices in
Ontario (888/433-5824).
The membrane is a 6-mm-thick (24-mil)
high-density polyethylene (HDPE) with a
matrix of round dimples, about 5/8 inch in
diameter, vacuum-formed into the sheet
(see Figure 1, next page). The dimples are
installed against the foundation and cause
the membrane to stand off the concrete by
about 5/16 inch, leaving an air space
between the membrane