Save Money by Insulating the Foundation Walls on Your Home

The December/January issue of Family Handyman magazine suggests we all consider insulating the foundation walls (on the outside of the house) to save big on heating costs. here's what they say (sorry, I couldn't find a link -- I have the hard copy of the article):

An uninsulated foundation accounts for up to 22 percent of the energy loss in a home. So insulation panels will improve your home's energy efficiency -- and its looks.

They refer their readers to Styro, a company that makes insulation panels. The panels actually look nice (see pictures of them on the Styro homepage after all the "energy loss" pictures are shown) so they not only save energy, but add to the beauty of your house (imagine replacing those concrete foundation walls with something that actually looked good.) They also have some stuff that you can paint on as well.

I've never heard about insulating your foundation walls from the outside. Anyone done this? Good or bad experiences with it? 

Comments

[Mike]

Finally, something to help warm up the master bathroom. The cement slab makes the floor pretty chilly.

[Bryan]

Outside? That sounds a bit silly, most concrete blocks have air inside and (as we know from having storm windows) contained air is a pretty good insulator. I know I've used the "great stuff" and some scrap pieces of insulation from local construction sites to tighten up things around the foundation...

[Quizme2000]

Whoa there Mr. Green, no savings here!

I've done many estimates for foundations that include insulation. There are only a few reason to insulate the exterior of a foundation slab, retaining wall, etc. and it doesn't have anything to do with saving money on energy cost. I'm a regular reader of family handyman and I'm disappointed with this recommendation that is at best suspect.

[Smart Girl]

Yes - a friend's home had this. The problem is that it is not considered a "green" product.

[Scott Moonen]

It seems to me that a bigger source of heat loss would be the ground itself. If you have a slab foundation, aren't you feeding far more heat straight into the ground's heat sink than you are feeding into the air?

[Susan]

As a mechanical engineer that designs heating and cooling systems for a living, typical heat losses through foundation walls compared to the heat losses through the entire house are in the range of 2-7%, even lower if your house has foundation vents since the air inside the crawlspace would be the culprit instead of the walls themselves. So to expect to save 22% off your heating bills by adding more insulation to your foundation walls is a very deceitful selling tactic. I see so many of these deceitful sales practices in the name of energy savings.

[Derek]

Building Science has done research on the best insulation strategies for different homes in different climates. They do recommend foundation insulation in certain cases, mostly in new construction. See http://www.buildingscience.com/ This site also has great information for building or remodeling any part of your home.