Founding on an Existing Footing
Founding on an Existing Footing
(OP)
Hello,
Not sure if there is a better section to pose this question but I thought I would start here.
I am running into a situation where we have done a foundation design (piers and footings) at a mill site and issued for construction. The owner is overseeing the excavation and the contractor has unearthed a large existing footing where we are proposing to place our new footing. The owner has contacted us and has suggested that we could possibly use the existing footing instead of demoing the footing and pouring a new one. I have expressed my concerns with the many unknowns regarding using the existing footing (no drawings available) and he has suggested that he would provide a letter taking on the risk of using that existing footing.
My question is - does anyone have an experience with this situation that could offer guidance? I am a bit unsure if what he describes is appropriate. Could we revise the drawing to indicate that that particular footing is "designed by others"? Also, we have a pier that we have designed which would need to be doweled into the existing footing, which may also cause issues of where our liability starts and ends.
Any insight into this would be appreciated! If you have any questions, please reply and I will do my best to answer them.
Thanks!
Not sure if there is a better section to pose this question but I thought I would start here.
I am running into a situation where we have done a foundation design (piers and footings) at a mill site and issued for construction. The owner is overseeing the excavation and the contractor has unearthed a large existing footing where we are proposing to place our new footing. The owner has contacted us and has suggested that we could possibly use the existing footing instead of demoing the footing and pouring a new one. I have expressed my concerns with the many unknowns regarding using the existing footing (no drawings available) and he has suggested that he would provide a letter taking on the risk of using that existing footing.
My question is - does anyone have an experience with this situation that could offer guidance? I am a bit unsure if what he describes is appropriate. Could we revise the drawing to indicate that that particular footing is "designed by others"? Also, we have a pier that we have designed which would need to be doweled into the existing footing, which may also cause issues of where our liability starts and ends.
Any insight into this would be appreciated! If you have any questions, please reply and I will do my best to answer them.
Thanks!





RE: Founding on an Existing Footing
Mike McCann, PE, SE (WA)
RE: Founding on an Existing Footing
RE: Founding on an Existing Footing
RE: Founding on an Existing Footing
RE: Founding on an Existing Footing
Mike McCann, PE, SE (WA)
RE: Founding on an Existing Footing
Would it be acceptable if I were to do a analysis using conservative properties as msquared48 suggested? Also, I would get the geotech on site to investigate the sub-grade under the footing and give me an appropriate bearing pressure.
Thoughts?
RE: Founding on an Existing Footing
RE: Founding on an Existing Footing
The client has elected to demo the existing footing and install a new one as originally planned.
Thanks for your assistance!