Chris' Sierra Build

[SableSprings]

Just another note of consequence here, the fact you have used 6:1 precast p/vcrete means it will not be as good an insulation as the "normal" 5:1 mix. This would make me much more strongly advise putting the CaSil on top (just below the cooking floor). I honestly don't know where you got the lime addition info, it's used in homebrew mortar and renders not the base insulation. It certainly won't hurt, but you shouldn't experience temps in the subfloor layer high enough to break down the Portland but might in the dome. The Hydrated Lime can tolerate higher temps and is slightly flexible when cured and thus more resistant to cracking. Portland cement will indeed break down under temps within the range of pizza oven firing, so the lime addition in the mortar is recommended. Once the dome is completed, it is self-supporting and could lose or have most of its mortar cracked and still be structurally sound (see photo below of Sorrento, Italy oven I once used).

Yes, your pcrete sections probably still contain a significant amount of water which needs to be driven out by the multiple, stepped curing fires, and in many cases just more time being used after curing.

[Travelinman]

Mike:

I really appreciate your time and feedback.

For Pcrete floor insulation, I used a 6:1 precast adding .5 part lime. So 12:2:1 Perlite, Portland Cement, Hydrated Lime. Why lime? I read somewhere here that high heat will breakdown Portland, not lime bonding. Also the Coliseum was build with lime and rock, only.
Anyway, it turned out pretty strong although crumbly on the edges. I can lift the quarter sections and move around. It is much heavier than I expected; maybe water retention??

I will consider your thoughts and balance against mine. Either way I will test temps with a temp gun. I will share results.

You are making me think about the design and that is good.

Thanks, Chris.

[SableSprings]

Not sure what the reason is for the hardware cloth, it's just more work and won't provide easier access/flow to weep holes. I also don't understand your question about separating the Casil without p/vcrete. Normally, the order of the base layers from the top hearth slab is water gap, CaSil board, possibly a thin layer of sand/clay mix for leveling, and finally your cooking floor bricks. It is also good practice to fully & equally insulate the oven to minimize uneven thermal stress during use. Resting your outer dome perimeter bricks on the lower proposed CaSil & then raising your cooking floor up on the p/vcrete sets up an uneven heating expansion situation. Probably not a major problem, but why take the risk?

In answer to your base insulation order, p/vcrete in precast sections can be difficult & fragile to handle (no lateral strength). So, most builders pour it in place first, allow it to dry, then place the much lighter, easier to handle, CaSil on top. Since your insulating concrete are dry sections, the order of base insulation layers would make no difference in total insulation value... However, heat will move down twice the distance in p/vcrete than it will in CaSil. This means although the "total insulation" is the same, more heat will transfer into the p/vcrete. I would guess the actual heating difference would be relatively minor...but if it's simply a matter of the placement order in your build, why not go for the optimum, recommended order?

These are really minor fine points and your oven is still going to produce great pizza as you're planning & give you plenty of excellent baking options like bread & roasts.

[Travelinman]

I attached a photo of my rough drawings, to show insulation.

I understand the suggestions about separating the CaSi from the bottom for avoiding moisture.

My question is this: Since it was recommended to use all CaSi, how would you separate without any pcrete or vcrete?

I honestly thick the 2 inches CaSi on the bottom with 4 inches of pcrete on top, is not different from 4 inches of CaSi, from a moisture standpoint. Am I missing something?

In either case, I want to use galvanized hardware cloth, then tile, then 2" CaSi, then 4" pcrete.

Thanks for you help!

[UtahBeehiver]

CaSi board is the best insulation under the fire bricks then the pcrete under it. The K value of CaSi is much better. Second, having the pcrete on the concrete hearth first raised the CaSi higher off the hearth making it less exposed to water ingressing into the hearth since it is so water absorbant; I believe Mike (aka SableSprings) said the same thing.

[Travelinman]

Thanks for your suggestions!

I already built a 2 inch layer of CFI, with the idea of placing the soldiers on top with an inch extra to stop sprawling. Then the 4 inch Perlcrete on top of CFI. The 42" precast Perlcrete inside the soldiers and on top CFI. Why would that be a bad idea? Why does CFI have to be on top?

Thanks, again

[SableSprings]

The weep holes are only through the concrete slab. If you get water seeping in, it will be traveling along the top of the concrete layer. If that does happen, you want to give it a little channel towards the weep hole...you don't need to take a hammer to the tiles (although using smaller tiles helps provide more "channels"). That's why I like to see the use of mosaic tile sheets used, laid upside down with the backing mesh supporting the pcrete. Because your cast pieces of pcrete are dry, you don't need to worry about blocking the channels with a pour of wet pcrete. Any moisture will be either forced down during the curing process or be able to exit up or down when just " air drying". Hope that makes sense.

[Travelinman]

SableSprings:

Thanks, I appreciate the response. I will follow your guidance.

My only question about this the the drip hole alignment. We are trying to provide a drain for water and steam and elevate the insulation. Since water and steam will find their way out, why line up the holes? I can drill holes in the perlcrete near the drip holes, since that will be under CFI. I take also take a ballpeen hammer to tiles and create more cracks.

The photo of bricks laid out, might be the non FB bricks I laid to mold the perlite 4" insulation in advance. It was a fast and effective mold.

Chris

[SableSprings]

Looks like a great start Chris. I would suggest placing your perlcrete sections on top of the tile and the CFI between the cooking floor bricks and the perlcrete. The CFI offers much better insulation value per inch and your perlcrete sections will be the secondary layer to retain any heat passing through the CFI. Do make sure to align the spaces between the tiles to your holes in the slab. I assume you are going to be cutting those full length bricks laid out as the dome base in your picture so they are all the basic half-brick length.

Again, the recommended layer order is concrete slab (with weep holes), tile pieces (gaps aligned with weep holes), perlcrete, CFI (possible thin layer of sand/clay for leveling), & finally the cooking floor bricks. Also don't forget to attach some insect screen to the underside of the weep holes to keep critters from exploring or making it home.

[Travelinman]

I have been going slowly, but here are some photos of my 42" Tuscan Dome.
I made a mold using loose bricks to pour the 42" perlcrete slab. This will be place in four sections. Used perlite due to comments on this forum about strength and water retention. I could have gone both ways, I just had both.
I used 4" tiles, I had left over, for the moisture separation. I put 5-6 1/2" holes in slab at pour.
Next:
I just put 2" CFI Board on top of tiles, to be followed by the perlcrete pre-cast sections. BUT
Todays big question:
What order should I put down the floor insulation?
Should I layer tile, then CFI, then Perlcrete, then fire brick?
Or, tile, Perlcrete sections, then CFI, then brick.
I am ready to lay down both, so I could use your advice.

Just saw Stanley Tucci's first episode of his Italian Food Tour. Lots of great NAPLES food and history. i.e. the sad reason Neapolitans loved or needed pizza. Reminded me of Naples and my foodie trip. I even got to cook in WFO ovens! Chris

[david s]

Before you do your floor insulation make some holes in the supporting slab to allow underfloor moisture somewhere to escape by.

[MarkJerling]

Well, I started. No going back! Next Phase is floor and soldiers.

Cool! It's a nice feeling to be out of the ground and up to slab level. Now the fun job begins!

[MarkJerling]

Looking good I'd love to take on a project like this but feel like I'd be in over my head.

You can do it. If I can, you can. I've never laid a single brick in my life before building my oven. Good luck!

[Travelinman]

Spizzaboy, it really is over my head too. The easy part is over for a novice!

[apizzaboy]

Looking good I'd love to take on a project like this but feel like I'd be in over my head.