Building on existing concrete patio

[boom]

Hi!

This looks like an amazing community. Would it be OK for me to ask some questions? First one, here goes!

I would like to build my pizza oven on an existing concrete patio at the back of the house.

Pretty much all the other builds I've seen have involved digging foundations into earth. In my case I would like to just build on top of the existing concrete.

So I guess I've got two questions...

1) The existing concrete isn't level (naturally, it slopes away from the house to drain water away from the house) - how should I obtain a level base?
a) Self-leveling concrete?
b) Shims or similar underneath the breeze blocks?
c) Cast a concrete block on top of the patio?
d) Other! Something I haven't thought of.

2) Will I NEED foundations? Or can I just 'stick' my structure onto the patio with mortar?

THANK YOU

[almondsurf]

Re: Building on existing concrete patio

I'm new at this stuff but how thick is your concrete patio? Could it support over a thousand pounds in the area of the oven?

You could always shim it up with mortar if its not too steep (tough to do though). You could drill straight into the patio and glue in some rebar to hold the concrete blocks vertically.

Also, what is the slope/grade of the patio?

[deejayoh]

Re: Building on existing concrete patio

If the concrete is at least 4 inches thick and has enough rebar in it, you're probably fine to use it. I set my oven partially on an existing slab and haven't had any issues.

As far as leveling goes - I suggest leveling it out using the cinder blocks and shim + level with mortar. Don't pour a thin layer of concrete over concrete. That will likely chip and spall over time.

Or you could cut out a section of the concrete with a rental concrete saw and pour a new level foundation.

[Tscarborough]

Re: Building on existing concrete patio

Your fat cousin exerts way more dynamic weight per square inch than a static oven ever will with the standard stand design.