Extended Footings

[BearcatEngineer]

Geotech is recommending extended footings to establish adequate bearing for a single story building. Anybody have some specs they recommend using. I think in the past we have used a 100 psi lean fill. Looking for a little advice.

 

[BigH]

I take it that you are extending the footings deeper to a more suitable stratum. You could use lean concrete (k-krete, flowable fill, etc.) 100 psi is fine. You could also use well graded crushed stone, etc. The concrete, though, is "more elegant" in that you don't have to worry about compaction and the headaches of working in confined spaces, etc. The extra cost of the lean mix would be offset by the time cost of placing small areas of fill in layers, compaction, in situ density testing, etc. Of course, this is all predicated on a "reasonable" depth. If you are talking of extending to, say 10 ft, then I would look at other options - short drilled shafts or similar.