The design of Styrofoam Wallmate
insulation was the answer to the perennial
demand for a simple way to insulate
and finish basement space. The
manufacturer put a 3/4-inch-deep by
11/2-inch-wide rabbet along each long
edge of a 2x8 piece of 11/2-inch-thick
extruded polystyrene board. When
two sheets are butted together, the
rabbets form a 3-inch-wide vertical
channel. When used to insulate an
entire wall, the rabbets form a series of
2-foot on-center channels that are just
big enough for 1x3 furring strips, which
can then be fastened through the insulation
and into the wall with Tapcontype
screws. The furring strips hold the
insulation in place and act as a screw
base for drywall.
Wallmate has an R-value of R-7.5
and