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RE: Footing Retrofit/Replacement Ideas

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You might try underpinning with something like these (mini-piles, helixes)

The installations generally quick (a day) and don’t disturb much of the current bearing soil. As mentioned by Ed, it is not likely to be under design load at that time anyway so you should be able to avoid shoring. The existing footing may have sufficient reinforcing to be supported at the edges already, or if you have enough room below the finished floor you could clean/roughen the footing surface and add some “hairpins” and concrete on top of the existing footing to improve “d”.

We have used both types successfully on several renovation projects, and there are an assortment of companies which make them. You might check with local “foundation repair” companies in your area about what is available.

Not being a geotech, I prefer to provide the GC with allowable and ultimate reactions for each pile and require their sub to submit singed/sealed calcs on the manufacturers system, components, and depth/torque requirements based on the geotechnical report.


Michelle Motchos, PE

Stevens & Wilkinson of SC

1501 Main St., Columbia SC 29201


-----Original Message-----
From: Ed Tornberg [mailto:ed(--nospam--at)]
Thursday, February 09, 2006 12:35 PM
To: seaint(--nospam--at)
Subject: RE: Footing Retrofit/Replacement Ideas


I suppose underpinning can mean different things, but is the shoring definitely required?  Often the maximum credible loads you will have during the retrofit will be considerably less than the total load the footing is designed for, especially if snow load is involved.


Disclaimer:  I know nothing about your soils; that may or may not be a determining factor.


Ed Tornberg

Tornberg Consulting, LLC


-----Original Message-----
From: Eknrinc(--nospam--at) [mailto:Eknrinc(--nospam--at)]
Thursday, February 09, 2006 06:50
To: seaint(--nospam--at)
Subject: Footing Retrofit/Replacement Ideas


I have a project which limits me to having to upgrade a concrete pad footing bearing area. The existing footing is 4' square x 12" deep. Here are my initial ideas:


1. Underpin (this requires shoring supported beams)

2. Demolish and replace (this requires shoring supported beams)

3. Pad extension on two sides (may run into existing reinforcement for continuous flexural reinforcement installation/coring) 


Any other ideas?


Thanks in advance.