Underpinning Foundations
Underpinning Foundations
(OP)
Fellows,
Is there an underpinning expert out there?
I was just wondering if concrete underpinning less than 4'-0" deep, for an existing concrete foundation wall, needs to be reinforced (I believe more than 4'-0" deep needs to be?!!).
If so, what is the best configuration of reinforcement: spliced horizontally; vertical reinforcement; other??
Thanks,
Hercul3es
Is there an underpinning expert out there?
I was just wondering if concrete underpinning less than 4'-0" deep, for an existing concrete foundation wall, needs to be reinforced (I believe more than 4'-0" deep needs to be?!!).
If so, what is the best configuration of reinforcement: spliced horizontally; vertical reinforcement; other??
Thanks,
Hercul3es






RE: Underpinning Foundations
I've never had to reinforce a 4' underpin. They usually end up being about 2' thick and compressed by axial load so it's never been necessary by the numbers. That said, you should run the numbers for your particular situation. Vertical rebar is not a big deal but horizontal reinforcing is pretty terrible constructibility wise.
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.
RE: Underpinning Foundations
www.PeirceEngineering.com
RE: Underpinning Foundations
RE: Underpinning Foundations
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.
RE: Underpinning Foundations
RE: Underpinning Foundations
Just one more question: do you recommend formwork (side-to-side) to pour the concrete piers?
Thanks again!
RE: Underpinning Foundations
RE: Underpinning Foundations
Installing reinforcing bars that jike mentioned may work for piers less than about 4 feet deep but they will greatly interfere with excavating for deeper underpinning piers. How can a worker fit inside a 4' wide pit if there are 2' long dowels coming at him from both sides? Also, what purpose is this reinforcing really serving? If the underpinning consists of continuous, adjacent piers, the underpinning is designed for overturning and sliding on a per linear foot of wall basis and there should be no shear between adjacent piers. If the underpinning consists of individual, spaced piers; there are no adjacent piers to dowel into. There is rarely a good reason to install reinforcing in underpinning piers.
www.PeirceEngineering.com
RE: Underpinning Foundations
Thank you so much for your help guys!
RE: Underpinning Foundations
"It is imperative Cunth doesn't get his hands on those codes."