Insulation in the basement seems like a foolish thing to do. After all, what could provide better protection then a very thick and heavy wall? The truth is that concrete has one of the lowest values of insulation. In fact I am certain that everyone who has spent time in basements has noticed a drop in temperature. This is not merely because it is below grade. This is the result of poor or no insulation. The basement is a conditioned space and should be comfortable just like the rest of the house.
Insulation values are rated as R-values. The higher the R-value, the better the insulation. Current energy code requirements state that exterior walls must have an insulating value of R-19 or better. This is so the expense of heating a home is not lost (or at least is greatly reduced) due to thermal failure in the walls. The same should hold true for basements. One should not “put up” with the discomfort of a chilly basement simply because that is the way it has always been.
This brings me back to R-values. Standard Batt insulation for a 2x6 exterior wall has a value of R-19. Compare that to concrete which has a value of R-0.08 for every inch. For a typical basement foundation wall of 8” that is a total value of R-0.64. YIKES!! Why wouldn’t you want to insulate your basement when so much energy is being lost through the walls? The best way to prevent this loss is to provide furring (built-out framing – more on this in a future post) at the perimeter wall and fill the cavities with insulation, just as you would any exterior wall above grade. The expense will be well worth every penny when you can spend every moment in your basement in comfort.