Results 1 to 7 of 7
  1. #1
    Larry Zatopek's Avatar
    Larry Zatopek Guest

    Default 6 mil poly under exterior grade beam?

    I was asked to looking at a foundation pior to pouring within the next several days. My question...Shouldn't 6 mil. poly be located under the exterior grade beam and up to the exterior form boards?

    Similar Threads:
    NHIE Practice Exam

  2. #2
    Join Date
    Jul 2010
    Location
    Tennessee
    Posts
    60

    Default Re: 6 mil poly under exterior grade beam?

    Why would you want to inspall poly under a footing? Size and proper depth are your critical points.


  3. #3
    FIA Ranch's Avatar
    FIA Ranch Guest

    Default Re: 6 mil poly under exterior grade beam?

    Quote Originally Posted by Larry Zatopek View Post
    I was asked to looking at a foundation pior to pouring within the next several days. My question...Shouldn't 6 mil. poly be located under the exterior grade beam and up to the exterior form boards?
    It is a good practice to run poly under (and at least partly up the exterior) of the grade beam in colder climates where there can be a dew point (condensation/mold) issue.

    Other than any local AHJ requirements, I don't know of any code requirements.

    Take a look at this document - Info-513: Slab Edge Insulation — Building Science Information


  4. #4
    Darrel Hood's Avatar
    Darrel Hood Guest

    Default Re: 6 mil poly under exterior grade beam?

    The required locations of the poly should be depicted in the engineered drawing. Some engineers require it to come up to the form boards, others just under the beams.

    Darrel Hood
    DILIGENT PROPERTY SERVICES


  5. #5
    Jeff Finley's Avatar
    Jeff Finley Guest

    Default Re: 6 mil poly under exterior grade beam?

    When inspecting this, remember if the 6 mil poly goes under the beams, you are defeating the concrete encased grounding electrodes required in 2008 NEC. Section 250.52 (A)(3) requires direct contact with the earth.


  6. #6
    Join Date
    Mar 2007
    Location
    Spring Hill (Nashville), TN
    Posts
    5,847

    Default Re: 6 mil poly under exterior grade beam?

    Quote Originally Posted by Larry Zatopek View Post
    I was asked to looking at a foundation pior to pouring within the next several days. My question...Shouldn't 6 mil. poly be located under the exterior grade beam and up to the exterior form boards?
    No, you do not want it under the footers. Under the slab, if it is a slab on grade.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  7. #7
    Joao Vieira's Avatar
    Joao Vieira Guest

    Default Re: 6 mil poly under exterior grade beam?

    Many builders and architects don't know or ignore the correct procedure when installing a vapor barrier under a slab on grade. 95% of the slabs I see do not reach the wall footings and the moisture will find it's way in.


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •