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FPSF when constructing an addition

Forrest_Tucker | Posted in General Questions on


 I’m trying to figure out how to connect the FPSF to my existing footing/stem wall foundation and also how to protect it from frost heave. (Zone 6)


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  1. Expert Member


    What type of FPSF are you considering? A slab? Stem walls?

  2. Forrest_Tucker | | #2

    I plan to do slab, one unheated style for the attached garage and the other heated space style for the bedroom addition.

  3. Expert Member


    Sorry - one more question: Is the existing house a slab, or does it have a framed floor on top of the stem walls?

    1. Forrest_Tucker | | #4

      Framed on top of stem walls.

      1. Expert Member
        MALCOLM TAYLOR | | #5


        That makes things complicated. With an slab, or a slab inside stem walls, you can attach the new FPSF slab to the existing and away you go.

        With framed floors you have to figure out a) the intersection of the framing and new slab when you essentially are burying the rim joist, and b) how to build up the exterior grade under the new slab while maintaining the required clearance to the framing at the existing house.

        The garage slab is no problem, as you can pour it at the same level as the existing foundation, but the bedroom addition might be best built with a framed floor. Both could be protected from freezing using FPSF techniques.

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