42" build in Arizona

[xvandish]

Hello all,

First, a thanks to all for the information and guidance in other threads, it's helped immensely.

Last week, finished the walls and finished filling every other core with rebar/cement. This week I've been buying some materials - chimney pipe and insulation.

I'm planning on a 4" concrete hearth pour with 1/2" rebar through the whole thing and 1/2" weep holes over the oven part of the hearth. I know the 1/2" rebar is pretty big, but It's what I've already bought, so rolling with it. The foundation slab is ~6-7" of concrete with 1/2" rebar through it as well, spaced at a 0.5'-1' grid depending on the spot.

Once the hearth is done, there will be a layer of mosaic tile, over which I'll place 6" of ceramic fiber board. Been raining and I need another pallet of concrete, but hopefully I can get the hearth poured this weekend!

The plan is counter/table on the left, oven on the right, so the foundation was shaped that way to save on some CMU and concrete for the counter since I figured the load would be minimal. In retrospect, not worth the time and complexity its caused whatsoever, although my slightly crooked forms didn't help matters either. Oh well, live and learn.

[UtahBeehiver]

Great start, what do you envision how the oven will be used, ie pizza, roast, etc or high volume bread production. Why I ask, 6" of CaSi board is really a lot of this high tech and expensive material. 4" is more than adequate. Be sure the CaSi has a compressive strength of at least 75 psia at 5% compression. There are some softer CaSi boards out there that don't have the compression strength to support a brick oven (there heavy)

[xvandish]

Thanks! Sure, thanks for pointing that out. I went with 6" as I'd like to fire the oven over the weekend and then use it throughout the week without having to re-fire. I'm imagining heavier tasks closer to the firing day (roasted veggies, fish, etc) and lighter tasks by the end of the week like warming up bread. And for intended use on the firing day, any and everything! Once it's built we'll probably adapt our cooking to the heat patterns during the week. Especially looking forward to using the oven during the summer, so we don't have to turn on the indoor oven/stovetop and heat up the house/kitchen.

I bought my board from Skyline Components and just checked their spec sheet, they list "Flexural Strength" for my board at 0.5 MPa which comes out to ~73PSI, which hopefully is close enough. One thing I'm regretting now is not getting the bio-soluble equivalent which actually costs the same. If you're interested I bought the B12T50A board listed here - (spec sheet link is at the top of that page too).

[Buzzard Bluff]

Looks like a lot of thought went into your design and planning. It will be fun to follow your progress.

[xvandish]

Looks like a lot of thought went into your design and planning. It will be fun to follow your progress.

Thanks Buzzard! It will be fun following yours as well.

Update - making decent progress on the internal framing, re-did it since I wasn't happy with the first attempt.

Before I pour the hearth I've got to: finish up the leftmost portion (out of frame) of interior framing, do the exterior framing which will take some time since I have counter and bar sized overhangs), lay down & cut the rebar, create a form for the sink that's going in on the leftmost side, cut the pvc for the weep and faucet holes aaand do some sanity checks.

Gonna be a full day tomorrow.

[xvandish]

I finished up the internal framing and started cutting the hardieboard and the external framing.

What would you guys recommend for covering the non-filled CMU holes? I've run out of concrete bags, and don't think I"ll get enough new empty bags to fill as I pour the hearth.

[Gulf]

Beer cans have been used by some. Just about anything can be used to keep from wasting concrete. Fill the holes up mostly with empty bottles and cans. Then just use a small amount of paper to seal off the top block.

[xvandish]

Thanks Gulf for the tip. Sorry for the late response. I ended going up with rocks, plenty of them here in AZ. Big rocks at bottom, finer on the way up. Worked well enough.

The heart is now poured! I finished pouring it Monday night, 30ish 80lb bags of concrete, took me about 7 hours solo. Still standing and looking good enough! Finishing the outside framing took forever - I added a bar overhang and some overhangs on the pizza oven side and that added lots of complexity in lots of places, plus even with best efforts the lumber I got had warps and curves that made leveling rough.

I sealed everything up with a combination of caulk and silicone sealant, which seemed to work ok, no leaks on any side, and I had some decent size gaps between cement board and block edge in places. I went with 3 weep holes on the right, and the sink form is 3" from edge, with faucet/soap-dispenser cutoffs 1" from edge of form.