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Polystyrene under a footing or load-bearing wall?

B_T_Student | Posted in General Questions on

Hey guys, what are your experiences with putting a 100 psi polystyrene under a footing to help eliminate as much thermal bridging as possible? This is for a residential setting. It would be in the center of the house the load of the first and second floor and possibly the roof would be on it.
Can anyone recommend a engineer that may have experience in this?

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  1. GBA Editor
    Martin Holladay | | #1

    Here is a link to an article that address the question: Foam Under Footings.

  2. wjrobinson | | #2

    x100lb/""/2 compression factoring
    =5000 pound load capacity, which residentially is a high load.

    In my area we frame with SPF which across grain PSI is limited to less than 500 PSI (330 for example in one use in one chart)

    Square inches added up can carry thousands of pounds even derated 50% of otherwise for various reasons of safety and compressability, vibration, earthquake, hurricane and asteroid landings yadda yadda.

    Mechanical engineering added factoring... is fun... the icing on the cake... Amazing that Roebling his son and daughter-in-law designed and built the Brooklyn bridge... while the father was dead, and the son was sick, she was there behind the scenes gettin err done. Three people, 1883 still looking good in 2014, figuring loads on paper with sharp pencils.

  3. jinmtvt | | #3

    100psi polyst foam, almost a solid block of plastic :p

    even my 40ft high 8" ICF walls wouldn't exceed this rating
    ( 36" wide base footings on 4500psf soil )

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