# Concrete form over uneven surface



## gregzoll (Dec 25, 2006)

Have you tried putting a level down to see how much difference there is between areas? If there is seepage after you pour, you would just grind or chisel for clean up. Otherwise you can chisel before you do the pour. Any chance of a picture of the area that you are dealing with, showing what you are talking about.


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## Ron6519 (Mar 28, 2007)

Depends on how bumpy. Slight irregularities will not be an issue. Just keep the mix away from the soupy side. A standard consistancy will leak a bit, but not much. If it's more then 1/2", use backer rod for the gaps and hold it down with a second piece of wood on the outside.


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## pls8xx (May 2, 2009)

Run duct tape along the uneven concrete with the edge even with the inside of where the form board will be (shown above in black. Run a second strip of duct tape as shown in blue. Set the form and fill the space between form and tape with spray foam. After the foam sets, use a sharp knife to trim the foam even with the inside of the form. Remove the excess foam and tape from the inside of the forming.


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## user1007 (Sep 23, 2009)

Not sure I fully understand what you are trying to accomplish. But why be mindset on concrete for the repair? Would an epoxy compound work? I use this stuff all the time for concrete repairs. It is lighter and stronger when cured. You can sculpt it as you go with some practice. 

www.abatron.com

Not sure about standing up to heat in a hearth though. You would have to ask the company I guess.


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## cvbrewer (Aug 16, 2011)

thanks everyone. I got the form made, and there only seem to be moderate gaps between the form and the existing concrete pad. I am going to try tape on the inside and spray foam or caulk on the outside.


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## oh'mike (Sep 18, 2009)

Pack the gap with plumbers putty.


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