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Community and Q&A

Alternative to a Frost-Protected Shallow Foundation

John Ranson | Posted in Green Building Techniques on

I wanted to build my house with a Frost-Protected Shallow Foundation. I’ve got a set of plans that I’ve been running by builders, and most don’t have any experience with them. The general response is “Foundations need to go down 42 inches around here.”

The general design for the house is:
Single floor
12″ Double walls with a bearing exterior wall.
FPSF Monolithic slab with full sub-slab insulation
Rochester, NY Climate Zone 5

I have a couple motivations for the FPSF:

1. I want the house to be accessible (not too many steps)
2. I don’t really want a basement.
3. I’m happy with a concrete floor.
4. It takes less excavation and concrete than a full basement.

Here’s the question: What should I consider as an alternative foundation that’s energy efficient, and keeps the house low to the ground and accessible?

–John

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    John,
    You don't need a different foundation plan. You need a contractor with an open mind.

  2. Stephen Sheehy | | #2

    John: you describe my house in your four points, but we opted for a typical four foot deep foundation. Is a FPSF significantly cheaper, given that most contractors are unfamiliar with the concept?
    That said, Martin is right. Any smart contractor should have no trouble building what you want.

  3. John Ranson | | #3

    Stephen,

    I agree, it's not clear it will save me money.

    With a standard foundation, how far above ground is your front door?

    --John

  4. Expert Member
    Malcolm Taylor | | #4

    John,
    Using a conventional foundation with a slab inside should make no difference to the height above grade. That distance is determined by the building code.
    Stephen did blog his build here on GBA. There are sections explaining how everything comes together.

  5. John Ranson | | #5

    Oh, I was being dense and thought he had a framed floor. Nevermind that.

    --John

  6. Expert Member
    Malcolm Taylor | | #6

    No, he has a very nice polished concrete floor:
    https://stephen1147.wordpress.com

  7. Stephen Sheehy | | #7

    John: my front door is under a roofed open porch. The floor is about six inches above grade. We designed it so if we ever needed a ramp, it would be easy to install.

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