HOW TO INSULATE BASEMENTS

Install rigid foam insulation in basements, both on the exterior and the interior.
Extruded polystyrene (sometimes called beadboard) is an economical choice for
larger areas, and it forms its own vapor retarding layer when properly installed and
sealed. High-density polystyrene and isocyanruate are denser insulation boards with
higher R-values. Isocyanurate usually has one or two foil faces. It is used to seal rim
joists but is a good choice for any basement wall location.

Improve insulation and thermal seals in attics and other parts of your house to
keep basements warmer in winter. By reducing the amount of warm air that escapes
through the roof, you will reduce the amount of cold air that is drawn in through the
basement walls to replace the air.

Seal furnace ducts to reduce air leakage. Use a combination of UL 181-rated duct
tape (foil tape) and duct mastic. If cold-air return ducts leak, for example, they will
draw air from the basement into the air supply system. As with heat loss through the
attic, this will cause fresh cold air to enter the basement and lower the ambient
temperature.

What is a Dry Wall

When building experts warn never to insulate a wall that isn’t dry, they
have something very specific in mind. A wall that appears dry to the
touch may not be classified as dry if it is constantly evaporating small
amounts of moisture that will be blocked if you install any kind of
vapor retarder (as is likely the case). A dry wall (suitable for interior
insulation) is one that is superficially dry to the touch and also meets
these criteria:
• Has a positive drainage system capable of removing water that
accumulates from any source (this is typically in the form of a sump
pump).
• The foundation wall and floor are structured to provide drainage of
water away from the house, often through the use of drain tiles and
footing drains.