Great post. As the recommended insulation values have changed over the years, most houses do not have enough insulation by current standards. We added insulation to our attic two years ago and the cost paid for itself in one year’s savings on heating oil (we cut our oil use in half).

The one place my house is lacking is the walls… we have 2×4 construction, so the cavity space is limited. I am planing on re-siding the house in the next year, at which point we may add R4 to the sheathing. In any case, good information as always.