Basement wall thickness

Originally Posted By: mike sheyngauz
This post was automatically imported from our archived forum.


We're building a house. Our plan calls for a 10" thick and 9'6" height basement walls. It was poured two months ago. Now we just discovered that the thickness ranges from 9" to 9.5". Does anybody know if this might be a potential problem for anything? Are there any standards how much this thickness can vary from the one that an architect/engineer calculated?

Today we also spoke to our contractor about it and he was trying to defend himself by saying that it's only a form that's 10" thick. So therefore the actual wall comes out thinner (0.5"-1"). Is this true? This doesn't look right to us.

Thanks to everyone in advance!

Originally Posted By: mboyett
This post was automatically imported from our archived forum.

Can the architect/engineer be asked that question? If so, then that’s what I would do. I would also ask for the answer in writing with his PE stamp as well.

Mike Boyett

Capital City Inspections

Austin, Tx

Originally Posted By: clawrenson
This post was automatically imported from our archived forum.

Check the local building code requirements. Although most home inspectors are not required by the SOP to determine the answer to your question - the local building authority could best provide your answer.

The thickness of a foundation wall is based on the distance of lateral earth pressure relative to unsupported height. The width or thickness depending on foundation wall material is determined by height and the location of the lateral support.

Example in Ontario Canada - based on your 9'-6 it would not meet code. The 9 1/2" wall would be inadequate. The maximum height for a foundation wall laterally supported at the top can only be 7'-7" and requires a 11 3/4" thick minimum wall thickness.

Ontario Home Inspections Inc.

Originally Posted By: ckratzer
This post was automatically imported from our archived forum.


The soil type and backfill height is the determining factor here.

This will take some research on your part because the IRC chart is too extensive to explain here but relatively simple to understand when you see it.The information you seek is on page 72 of the 2003 IRC book,table R404.1.1(1). Also page 61 explains soil types in chart R401.4.1Your builder should have access to a copy. It can also be found at a book store.