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Narrow Concrete Foundation Walls

drstjohn's picture

Hi All,

Great forum.  First time post.  Could use some advice.  Is there any reason I can't or shouldn't have 4" wide foundation walls for a small (16x16) outbuilding, if they are sufficient to keep the soil load below the maximum permissible?  Can I use such walls without pouring a separate footing, if the bearing surface of the wall itself is suffient for the load and soil?

Narrow footing/stem wall (post #207366, reply #1 of 1)

If you are going to be building this with a building permit and meeting International Residential Code, I don't think so. The last time I looked, the minimun width of the footing is 12" no matter what the actual bearing capacity of the soil.  So if you don't want to pour a seperate footing, the stem wall will need to be 12" also.

If your thinking is that by making the footing/stem wall only 4" you will be saving a lot of money, I not sure that will be the case.  My guess is that the excavation cost would not be less.  The setting of the forms, the installation & tying of the steel may even be more difficult and costly for the 4"  stem wall.  You may save on the concrete.  On the other hand the amount that winds up on the ground after missing the narrow form opening may offset any savings.  Getting a good distribution of the concrete in the narrow  form could also be difficult.

I suppose that if you had an engineering firm test your soil and provide sealed/signed engineered drawings for submitting to your building department, you might be able to do this.  Good Luck