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Excavation and concrete question

joenorm | Posted in General Questions on

I have recently dug for a perimeter foundation, found the soils to be pretty heavy in clay but very homogenous and solid, difficult to pound a stake into when dry.

It’s spring here in the Pacific Northwest and it has been pretty wet since the dig, needless to say the site has some standing puddling water even though it does drain to daylight.

Of course the uppermost clay layer becomes soft and and there would not be much to cure that besides waiting quite awhile for the site to dry out.

I could hire a geotechnical engineer to come out, but that’s another $3K added onto a budget build. All the local contractors do not have much concern with the clays in our area, even when when. They say “go for it, no problem”

Any thoughts on this situation, it just feels criminal to pour concrete onto a squishy 2 inches of basically mud. Or is this just par for the course in wet areas?

I suppose that is why a footer is 16 inches wide, to distribute that pressure.

My concern is not so much the soils I am in, but the fact that at the moment they are wet and will not be able to dry before we pour if we want to keep any sort of schedule.


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  1. GBA Editor
    Martin Holladay | | #1

    In many areas of the country, contractors spread a 3-inch or 4-inch layer of crushed stone in a hole like yours before they set up the footing forms. Check with your local code official to see if that's acceptable in your area. (Some inspectors take the words "undisturbed soil" literally -- but I'd rather see some crushed stone in a hole like yours rather than mud.)

  2. Peter Yost | | #2

    Hi Joe -

    If the soils don't have expansive clay, I have never heard of how wet the soil is affecting when a footing is cast. If you have expansive clay, then there are code considerations, such as Soil Testing (R401.4), Foundations on Expansive Soils (R403.1.8).


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