We recommend using rigid foam insulation in most cases because it has a high R-value and will boost your energy savings. It's recyclable when you need to replace it, and it's more affordable than some other high-R-value insulations.

Costs vary significantly by size of the home, location and accessibility of added insulation, etc., but you can expect the cost of a professional job to be two or three times more than just the cost of the materials you'd need to do it yourself if you purchase fiberglass or mineral wool insulation.