Hi Foundations Experts,
I had a foundation on a 1915 house underpinned. A structural engineering did up the drawings and as the house is in an earth quake zone I believe some of the features were to seismically upgrade it.
The original concrete foundation wall was painted white. In order to underpin the wall and tie it into the old wall holes were drilled horizontally into the wall and rebar pins were epoxied in place. Vertical and horizontal rebar was then tied into the pins and 4 foot sections of the wall were formed using dirt on one side under the wall and plywood 2x construction on the other.
My first is should the original concrete wall have been wire brushed to remove the paint or will the rebar and pin tie in system properly allow the new overlapping and underpinning concrete to form a strong enough bond. I had a gc who took care of the project but the biggest problem I had with him was to do with his direct employees who were little more than labourers and his lack of supervison on the project which led to imperfect work.
Project is done but I am interested to hear what professionals would have done. Is it too small a detail to wire brush the paint to ensure a proper concrete bond?
Thanks,
Learner
Replies
Not a big deal at all. Bonding of concrete surface to surface creates almost no lateral strength. Any strength you get comes from your rebar.
As long as they installed the proper spacing of rebar and all the earth under is virgin you will be fine.
Edited 3/15/2007 12:47 pm ET by AllTrade
I'm looking at a similar project on my own home. Any advice on finding an engineer to do the design? What kind of engineer did you look for and how did you select the engineer?
I had a gc running the project and he had done several underpinning jobs in the past and presumably used the same engineer for this one. The engineer actually only lived a few blocks from the project which made getting documents and having him inspect it quite convienent.If I had to find one on my own I'd probably open up the yellow pages and locate some that are close to my house and then call them up and ask them if they have done any underpinning jobs in the past. I imagine they'd be listed under structural engineers.