# footings below water table



## abacab (Sep 16, 2009)

I'm wondering if anybody can give me advise on a foundation below the water table. This is actually a garage attached to the house with living area above the garage. The existing house is old and has only about a 1' footing. This structure is on a lake and the water table is 12-18" below the ground level. I want to put in a 4' foundation wall on top of a 12" or more footing about 32" wide. The building inspector so far says no, and that I need an insulated shallow foundation with an engineers stamp. The problem I see is that there is about 4' of loamy soil that I am trying to get beneath, and good sand underneath. Does anybody have experience with a footing sitting below the water table? Hydrostatic pressure would be the same on both sides of the wall, I'm not trying to create a dam to keep water out of a basement or anything.

P.S. this is Michigan, near Kalamazoo


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## TimberlineMD (Jan 15, 2008)

This may help...

http://www.deckmagazine.com/Images/Building a Stationary Dock_tcm122-1384394.pdf


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## CompleteW&D (May 28, 2011)

That was an interesting read.... Thanks for sharing.


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## Chris Johnson (Apr 19, 2007)

You need an engineer to start, the shallow footing detail works, but only on solid virgin soil with proper bearing capacity, so the inspector is right but also wrong based on your claim of the soil.

You will need piers or helicoil to get solid from the lower ground thru the loam to underside of footing, the footing will then become a grade beam and then your foundation wall or stem wall will be on that, sometimes the grade beam can be built to also be the stem wall in one. Your soon to be hired engineer will help you make that decision.


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## CarpenterSFO (Dec 12, 2012)

abacab said:


> ...The building inspector so far says no, and that I need an insulated shallow foundation with an engineers stamp. .....


Go have the $200 conversation with an engineer. You're going to need the engineer's stamp either way.


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## fear4freedom (Aug 23, 2015)

What type of floor you going to do and how thick?


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## abacab (Sep 16, 2009)

We are going with the helical piers, about 26,000 to do the house and garage. The garage floor is 4" thick.


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