I just purchased a house that was built and finished this year.

My house is backed up to a hill, and the foundation walls get shorter from the front of house (8 feet) to the back (a little over 2.5 feet), with above ground windows. There is foil type installation around the wooden wall areas and a white blanket around cement areas about halfway down the wall from start of foundation at top. The back area where the foundation is only 2.5 ft tall there is no white blanket installation. Just the foil type covering with pink installation around the above ground area and around windows.

Should there be insulation around the cement for this shallow area too? I live in Illinois, an hour from Chicago.



  • 2
    Your city or town almost certainly has a building department that would be happy to answer your question about local codes. – Yehuda_NYC Dec 22 '16 at 0:15

All areas that are above ground should have insulation. R-20 would be about the minimum - what you should ever do. You can ask your local inspector and they will possibly differ and want more or less. I myself do about R-30ish for basements and live close to you.

I just did my own basement 4 years ago and used Roxul at about R-30 depth and only did the portion about one foot below grade (my basement only shows 1 foot) and my basement is an oven now in the winter, even when we close vents.

In our region the biggest concern isn't the insulation on the outer wall concrete, it is making sure the joist area is packed and no air gaps. Just doing that will be 80-90% of the conservation of energy. The walls, while doing them is fine, remember that for all of the warming effects in the winter, you will lose cooling effects during the other seasons. You have way more basement above grade than I do so what you have seems OK, but I would check the joist area.

  • Thanks for the response. That's the thing too.. It gets pretty cold in the basement, for the amount of insulation there is. Especially in that area.. Mostly around the windows, I know there is a weep hole for the window that lets a draft in which I plugged with some paper towel for now, just to stop cold air flow a little. The frame around the window isn't really insulated up or anything. I will update with a picture. – eaglei22 Dec 22 '16 at 22:48
  • You should tape around your windows then insulate. Windows should get insulation 1 foot past all around. But still joists are the main culprit. Just know that insulating against pure concrete is hardly effective unless you are much more north and in that case you do it from the outside or at least R40. But yes windows we overinsulate the area after we get rid of the air gaps. – DMoore Dec 22 '16 at 22:53
  • Okay, how do you insulate around the windows, would it be the blanket type or just put the R-30 and wrap it in that tin foil wrap.. I have never done any of this but just in case I have to do this myself. Thank you. – eaglei22 Dec 22 '16 at 23:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.