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Normal dimensions of grade-beam (edge) for monolithic slab?

SierraWayfarer | Posted in General Questions on

I am wondering how big (depth and width) the thickened edge of a monolithic slab is for a single story house on good soil?

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  1. tallpinescabin | | #1

    In my 20x30 single story build, I asked for 12" thick, 12" wide, down to 4" in the field. I think I got about 10" thick, not positive how wide exactly, probably 10-12", and about 3 1/2" in the center, I think.

    Not too hard to do the math on what you'd need, depending on building width, snow loads, etc.

  2. plumb_bob | | #2

    12"x12" at the footing is typical for a smaller building, keep in mind that under some (most?) codes a structural slab is required to be engineered and the EOR will determine the dimensions and reinforcement.

  3. Expert Member


    As plumb-bob said, the dimensions largely depend on how the slab is engineered. Some monolithic slabs are not thickened at the perimeter at all.

    Structural concerns aside, you need a certain dimension from grade to the top of the slab (typically 6" to 8"), and a certain depth below grade to accommodate perimeter drains and rock with some soil above, so those dimensions may dictate the total depth.

  4. SierraWayfarer | | #4

    Nate, Plumb-bob, and Malcolm,

    I am going to work up slab/wall detail which I will post to see if concrete guys could form and pour it and what people think about it in general.

    Also needed to get an idea on concrete costs for my slab.


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