Posted on August 8, 2011 by Scott Gibson
Peter Fusaro is building a high-efficiency house on spec, and his plans include insulating the foundation walls. The question is how.
One option is to apply rigid foam to the outside of the foundation. That would leave roughly 1 ft. of insulation above grade, and Fusaro is concerned about how durable the foam would be.
Another possibility is to use a sandwich of 2 in. of foam between two outer faces of concrete, each 4 in. thick, making an assembly with both structural and thermal properties. He’s been told a wall built that way would have an effective R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor.