base

[Helen E. Cejtin]

this is my first post...we are about to start building an oven on top of a concrete patio. Do I just build the concrete base on top of the concrete patio, or do I need to remove the concrete with a jackhammer and then put down concrete on ground?

[Gulf]

Hi Helen,

Welcome to the forum. That is a difficult question to answer without a whole bunch of other info. Not knowing how the patio concrete was installed or the ground underneath was prepared leaves a lot of questions. Someone in Chicago may be able to answer it better. A local contractor or concrete person may be an even better source. Truth is, DIY ovens can get very heavy. Frost heave is a problem in your climate. Do check around for some advice locally to be sure. I know that there are lots of Chicago builds on this forum. I hope some of those members will reply.

[Chach]

Hi iI'mm from chicago and I myself would not build on top of the existing patio. I would cut out where the oven would sit. I put down 8" of grade 7 stone and I poured 7" of concrete. I did that much concrete because of the weight of my build I also have a fireplace I made so that is pretty heavy at about 15,000 lbs. I kept the pad the same all the way in my project. rebar is important to reinforce the concrete. I also did that much stone to have a strong base as I compacted it in 2" lifts and also created drainage under the slab. with that crazy polar vortex we had last winter my slab did not move.