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Author Topic: Pizza oven build insulation questions  (Read 224 times)

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Offline stevon

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Pizza oven build insulation questions
« on: April 08, 2021, 02:00:34 AM »
Guy's,

Novice here and have a few general wood fired Pizza oven build questions. Oven is a Dome Oven DIY Segmented Model - Large Pizza Oven KIT. My masonry oven stand isn't built yet so I can still adjust the finished oven floor height. I'm working with a contractor who never built a pizza oven (this will be his first). We have had problems communicating already. At first he dug or "scratched the earth" down 1.5 inches for the slab on the ground while I wasn't there. We had agreed to a 4.5 inch rebar slab beforehand. Came home from work and was so angry at what he did that I got out my hammer drill and dug down/shoveled out the pad hole to a 6" depth in the rock hard clay after work. I figured that 1.5" gravel + 4.5" finished slab top to be installed at ground level (no step). This was all agreed to before he got a deposit and I believed that he understood. When he came back on the weekend with his crew it was done right, see pictures. Before the cinder/cement block is laid I have instructed him to build the block height to 36" with a 4" rebar reinforced slab to be poured on top. But I think this is too high with extra insulation. Stand top design now is at 40", planned to add 2" ceramic fiber board + 2" fire brick floor makes the oven floor height already at 44"  Which is the absolute max I could cook with. I have read here and elsewhere that 4" insulation under the oven floor is only "OK" but on the other hand I can't just keep making changes to the plan or my contractor will walk when he comes by this weekend. Guess I'll have to figure (negotiate) a reasonable block height  of 32" to 36" of installed block height under the a slab top of 4" thick. Question: Will 2" of perlite/cement and the 2" ceramic fiber board be adequate insulation? then to place aluminum foil on top of the perlite/cement as a vapor barrier under the Cement fiber board? then add 1" sand then place oven floor? I have no experience with this stuff but want to do it right or not do it at all.

Stephen
« Last Edit: April 08, 2021, 02:36:18 PM by stevon »

Offline stevon

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Re: Pizza oven build insulation questions
« Reply #1 on: April 08, 2021, 02:36:42 AM »
Actual measurements planned now.

Stephen

Offline Jon in Albany

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Re: Pizza oven build insulation questions
« Reply #2 on: April 08, 2021, 09:15:28 AM »
The rule of thumb for oven floor height is about your elbow. Lower than that and you are bending over to look in. But it is definitely a personal preference. I would recommend stacking some blocks or creating a setup to try out a floor height with a peel. Keep in mind you will be looking through the oven entry and not just down at the peel. Ideally, you won't have to constantly hunch over to look inside. I'd skip sand on top of the insulation board unless it was needed for leveling. If you are level under the insulation board, the top will be level too. Probably easier to place the floor pieces on something solid than dealing with sand. Are the insulation instructions that come with the kit? I've never heard of this particular oven.

Another thing to think about is keeping your insulation dry. I'm not sure how you plan to enclose everything, but you will want to keep your insulation dry.

And lastly, I'm hoping "cement fiber board" is a typo and you meant ceramic. You had ceramic in your other post. Cement board like Wonderboard is not what you want under the oven.

Offline stevon

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Re: Pizza oven build insulation questions
« Reply #3 on: April 08, 2021, 10:04:07 AM »
My Plans.....

Stephen

Offline stevon

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Re: Pizza oven build insulation questions
« Reply #4 on: April 08, 2021, 11:11:02 AM »
Jon in Albany,

Thanks for the knowledgeable advice, this has become quite the project! Yes the "Cement board" is actually Ceramic Fiber Board insulation that I bought locally at McGills warehouse supply (1 - case 2" Ceramic Fiber Boards (two sheets) hf102 $79.22) I hope this is the right stuff.
It is a little short so I will be using trimmed sections from the curved floor with some perlite/cement mix to put under the tongue section for insulation and support, also bought some ceramic Fiber 4 x 9 inch blocks from eBay. Yes water proofing is part of my planning along with a ceramic fiber blanket, then rendering and final finish. providing a roof or at least tie down of covering tarp is planned but that's a ways from being a major concern at this point....

Stephen
« Last Edit: April 08, 2021, 01:08:50 PM by stevon »

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Offline stevon

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Re: Pizza oven build insulation questions
« Reply #5 on: April 21, 2021, 02:40:22 PM »
Guy's,

Some progress and built the framing myself because the contractor (laborer) said he had no idea how to do it. Purchased some scrap galvanized steel angle iron and put Hardi board (cement board) as the bottom, temporarily supported by extra  Cement blocks (purchased a full pallet 90 blocks, saves $0.21 per block). The frame is welded together (have welders available) The contractor is leaving me hanging for a couple of days now. I don't know if he will show up to finish the slab top or not, picked up the concrete needed Home Depot "expert" calculated how many bags I needed and added one bag of "plastic" cement. This is used for the top coat to float out smooth later. Promise to tally up the total cost of materials and labor when I'm done.

Stephen

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