Adjacent Footings & 2:1 Slope 1

[BSVBD]

For the past 20 years, i've enforced a 2:1 soil slope requirement for adjacent footings, but, i cannot find any current code documentation to verify this. I'm in Wisconsin which is currently under IBC 2009.

I've been looking for code documentation, on and off throughout the years as i am confronted with this every other month, but, i have not found it. Fortunately, i've been dealing with contractors who accept my, apparently reasonable enough explanations, so i haven't been forced to locate an exact reference. However, i need to find this reference for good practice.

I BELIEVE the origin of this specification came either from earlier codes or OSHA, but, i'm not coming up with anything.

Is this IBC, OSHA, ASCE or other?

Does anyone have a reference to this?

Thank you!

 

[KootK]

In my neck of the woods, the slope is specified in the geotechincal report, or should be. That said, I've never seen anything shallower than 2:1 or steeper than 1:1 in non-rock strata. 10:7 seems popular out east but they tend to have better material.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[straub46]

OSHA 1926.652 has the requirements for sloping and trenching for excavations during construction. It allows slightly steeper slopes that 2:1, see Table B-1 in Appendix B.

Go Bucks!

 

[manstrom]

Depends on the soil. The geotech should give you guidance. 2:1 is conservative.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[BSVBD]

According to OSHA Table B-1 (that straub46 directed me to), the shallowest required slope is 1.5:1 or 34 degrees, which is closely equivalent to KootK's 10:7.

 

[TLHS]

Look out, because regardless of the grade of the slope, building close to the edge can effect your bearing capacity. You end up losing confinement against bearing failure on the slope side.