Return to the Basements Forum | Post a Follow-Up

 o
XPS under radiant floor? open vs. closed-cell spray foam walls?

Posted by infohound2006 (My Page) on
Mon, May 11, 09 at 5:13

Hi folks,

I have two important questions regarding insulation for our basement which will be our rec / media room.

1. Should we insulate the concrete floor by extruded polystyrene (XPS) below our radiant heating panels? (the current plan is a thin poly sheet, Rehau Raupanel, + floating engineered wood).

2. We want to foam the cold concrete-block walls, and our GC is recommending open-cell spray foam rather than closed-cell foam, "so that the concrete can dry to the inside". (Now that I've read Building Science articles, I'd have gone for XPS panels there too, but our GC has already built a framework of metal studs in front of the concrete, and Paraseal waterproofing memmbrane on the outside)

I know that the cc is a vapor retarder, not a barrier, but I'm especially skeptical of the open-cell foam below-ground because it can absorb moisture. Am I right? Can someone point me to a Building Science or other respectable reference?

3. For sound-control of the ceiling, what are the relative costs of QuietRock, open-cell foam, and ???. (remember, this will be a pool / media room)

Thanks,

PS. We're in the high-labor-cost SF Bay Area.


Follow-Up Postings:

 o
RE: XPS under radiant floor? open vs. closed-cell spray foam wa

According to Dr. Joe, either type of foam is acceptable.

See "Understanding Foundations" (See Link) p. 6 .

I prefer cc foam because its higher R Value means it uses less space. Also, when applied on cold surfaces, the oc foam shrinks back.

Here is a link that might be useful: Understanding Foundations


 o
RE: XPS under radiant floor? followup

For soundproofing, use soundproofing materials--either constrained layer damping drywall, such as Quietrock brand or multiple drywall layers and Green Glue. Before the constrained layer drywall was invented, I used multiple layers on resilient channel. Lots of labour that can be easily short-circuited by just one wrong fastener, research shows.


 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