Return to the Basements Forum | Post a Follow-Up

Question for Worthy.

Posted by cheri127 (My Page) on
Sat, May 19, 12 at 15:40

Hi Worthy. I have read and re-read Lstiburek's crawl space paper and I think I finally get it. Could you tell me if this is right? One can completely cover the wood joists with spray foam as long as one uses 3" high density foam? The reason the open pier approach works is because the crawl space isn't colder than the outside air?

If all this is true, would I be able to correct my flawed crawl space by
1) covering the floor with a 20 mil vapor barrier
2) remove batting then spray the wood with 3" of high denisty foam
3) continue to use SaniDry dehumidifier

I can't do the open pier approach because most of the crawl space is below grade.

I have read many of your posts recently they are so informative. Thanks for taking the time to share so much information.

Follow-Up Postings:

RE: Question for Worthy.

You overlooked two steps:

1) a drying mechanism--such as a supply of conditioned air from the interior and exhaust (See link--Figures 2, 3, 4)

2) insulation on the perimeter walls--spf or extruded polystyrene board (XPS)

The 20 mil barrier is overkill if you're not using the crawlspace.

Here is a link that might be useful: Conditioned Crawlspace Construction


If you're insulating the perimeter, forget insulating the ceiling.

 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