Return to the Basements Forum | Post a Follow-Up

XPS or No....I noticed this

Posted by andrelaplume2 (My Page) on
Wed, Sep 17, 08 at 16:29

I have been struggling with weather or not to use XPS. I was in my Dad's 22 year old 4 star energy efficient PPL home with finished basement an noticed that his poured concrete walls were insulated as follows:

Pourced Concrete Wall, Plastic Sheet directly against that, white 1/2" styrafoam against that. Thats it! He does have a section drywalled. I assume they just studded in front of the foam. I found the plastic in between the foam and concrete interesting.

Of course the styrafoam of 22 years ago is likely different than the XPS of today.

It seems the methods are always changing.

Follow-Up Postings:

RE: XPS or No....I noticed this

The white foam is probably expanded polystyrene (EPS) like the stuff in coffee cups. If they had omitted the plastic it would have been perfect, though lacking in R-value. If the plastic runs right to the top, there's no way for the wall to dry either way. At least, the foam should be essentially undamaged by any condensing vapour on either side of the plastic. Nowadays Fire/Building Codes require the foam to be covered by a 15-minute thermal barrier.

Twenty years ago, I was using the worst but most common method: fiberglass batts with poly to the inside and often poly against the wall too. But I would run the concrete-side poly down under the drywall, which was cut an inch above the floor. The idea was that any condensing vapour would then run back into the finished space. I learned of that technique somewhere in the "expert" literature of the time.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Basements Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here