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Video: Installing Rigid Foam Under Footings

This construction site video of the Karuna House in Yamhill County, Oregon, demonstrates installation of a geofoam foundation that will superinsulate the bottom of the building envelope and help the project achieve Passive House and Minergie-P-ECO certifications.

Lead Carpenter Scott Gunter narrates the process of:

  • screeding out gravel,
  • back dragging with rake as needed,
  • compacting gravel,
  • marking outside foundation wall line on foam,
  • setting and aligning geofoam, and
  • drilling and pinning geofoam into place.

The Karuna House is designed by Holst Architecture and built by Hammer & Hand.

For more information on this topic, see Foam Under Footings.

Installing rigid foam under a footing in Yamhill County, Oregon

Karuna Passive House – geofoam foundation installation with Hammer & Hand’s Scott Gunter from HammerAndHand on Vimeo.


  1. John Klingel | | #1

    What psi foam is used? It
    What psi foam is used? It would be nice to see how they build the footer forms, etc, as well.

  2. Skylar Swinford | | #2

    Foam PSI

    Thank you for checking out the video. Under the footings we are using 2.40-2.50 lb/ft3 EPS39 (Geofoam title) or Type XIV (EPS title). Under the slab we are utilizing 1.35 -1.50 lb/ft3 EPS22 or Type II.

    More info can be found on the project website:,_delivered/

    Hopefully by next week we will have a video of the next steps in the process. Our intent is to document the project each step of the way.

  3. Tom Gocze | | #3

    Is my concern of ants, termites or critters living in this amount of insulation founded?
    We have done foam panel foundations, but wrapped the foam in 65mil EPDM. I was still a littler nervous about something getting in.

    I wonder if building an uninsulated foundation system is more prudent and then superinsulating inside the basement or on top of a slab and decking over that. I don't know but wonder if it makes sense.

  4. Kevin Dickson, MSME | | #4

    Two Big Reasons for "Outsulation"

    Insulating the outside provides at least two hidden cost savings, in addition to adding beneficial thermal mass:

    1. The concrete can be stained and polished for a durable, almost free floor surface.
    2. Insulating the outside and applying Frost-Protected-Shallow-Foundation principles, the thickened edge slab can be only 16" deep throughout the US.

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