Clarification on 2G90 cooking floor

[GreenBldr]

I'm constructing the Casa 2G90 oven on a concrete slab in an indoor location.

The "Installation and Operating Manual" specifies laying the cooking surface bricks on a "3/8" layer of fine sand using a notched trowel" and "butting the joints tightly together".

However, the "Online Instructions" describe laying them loosely and using the refractory mortar to bed the surface with "a thin layer of refractory mortar using a 3/8" notched trowel."

Furthermore, it instructs "Fill the joints between the cooking surface elements with refractory mortar."

What is the proper 2G90 method?

Using "fine sand", which I presume is common sand available locally, or using the mortar?

Butt the brick elements tightly together, leaving a space around the outside near the oven wall, or take up the room by spacing them all equally?

Fill the spaces with sand or mortar or just allow ashes to collect there?

[SableSprings]

Re: Clarification on 2G90 cooking floor

I helped a friend install a CasaG90 in Canada this summer and we used sand between the insulation board and hearth "plates". We found that using moistened builder's sand (do use a notched trowel and don't just use beach sand) under the tiles allowed us to level them a lot more easily.

My understanding is that when you are using bricks for the hearth, the sand is the way to go for two reasons; 1) if a brick is damaged it can easily be replaced--not realistic with the kit hearth pieces and 2) the sand allows some movement for expansion during firing but the mortar does not. I'd go with the sand again if I did another install. We butted the hearth pieces together as closely as we could and assumed it would be better to have a small gap between the outer dome pieces and the hearth floor.

Also found out that when you place the outer formed pieces on the base, the weight and movement needed to get them in position can make you "lose your level" on the hearth tiles. It was nice to be able to tap & work them back into a relatively flat position with the sand underneath. After the dome and hearth were in place, we brushed sand in to partially fill around the outer edges. Ashes have completed the fill-in now and sealed off the sand from the pizza.

[GreenBldr]

Re: Clarification on 2G90 cooking floor

What excellent and complete advice! Makes a lot of sense.

Thank you for the timely response. I'm literally doing it right now and was going to have to wing it!

[GreenBldr]

Re: Clarification on 2G90 cooking floor

Well, it's done now. I set it up with the hearth plates on a bed of sand, level and as close together as possible. Since the oven is inside an enclosure, it got tricky trying to stand around the edges of the concrete hearth on my toes. I had to use a block and tackle to pull up the pieces to the hearth height and then woof them into position by myself. The hearth plates got a little disturbed while setting the three dome pieces in place, but I was able to reach through the opening using an aluminum pry bar and tap and lever them pretty much back into position.

There is about a half inch gap between the edges of the hearth bricks and the shell of the dome. I didn't want my sand bed to squeeze up in there and allow the plates to become uneven, so I brushed sand into the gaps (very fine white silica sand). Lots of tapping everywhere with a rubber mallet and the hearth plates seemed to firm up some and become more stable as the sand settled. After I brushed some sand into the very narrow gaps between the plates, nearly all the movement stopped and I'm pretty happy with it.

I'm hoping that the very fine sand has enough give so it won't lock up when the plates and dome start expanding with heat. The 100# bag of silica sand was about USD8.00 or so at the orange box store.

[SableSprings]

Re: Clarification on 2G90 cooking floor

Great to hear you got the floor set and dome pieces in place. I'm impressed you got the dome pieces set by yourself...there were two of us and we really could have used a third person. I'm sure the sand will be fine and once you start firing it up, the ash will fill-in & make the "gaps" invisible. I suspect that the sand will take/make the expansion during firing a "no issue" issue. Congrats & welcome to the next phase...actually using the oven!

[GreenBldr]

Re: Clarification on 2G90 cooking floor

Seedy barley loaves? Bleu Cheese Souffle?

OMG :-)

It's all I can do to wait a week before firing and I don't even have the pipe on yet.

[HeidiL2011]

Re: Clarification on 2G90 cooking floor

GreenBldr,

Glad you hear your oven is coming along. We look forward to photos once it is completed.

You can add fine sand around the edges of the cooking floor to fill the gap or over time it will fill up with ashes and the gap will not be noticeable.

Please feel free to contact by email at Heidi@fornobravo.com or by phone 1-800-407-5119 ext 14, if you have any questions.

Thanks,
Heidi