sand under firebricks?

[cobblerdave]

David s
Again thanks for clearing things up... your a font of knowledge.
I think I have made a wrong asumption after reading that the slurry left with a bricksaw was a source of fireclay

Regards Dave

[david s]

Originally Posted by Poetryart

My clay is a low fire terra cotta, so it won't work, I fire it at about cone 06. Does anyone ever just set the firebricks directly on the FB board? Can I put a layer of vermiculite down? Regular sand is probably not a good idea, as one really good fire could melt it into glass? I've melted bottles in my kiln before at 06.
I really appreciate the advice - I would have never attempted building a WFO before this website. If I get the refractory/ fireplace mortar I won't need the homebrew? Is that correct?

Just use your terra cotta clay, but crush it up to powder then mix it 50/50 with sand. an 06 cone is around 1000 C you won't get anywhere near that. To melt terra cotta you would have to fire it up to stoneware temps.You canpurchase the refractory mortar, but be careful, some of them only work when fired to much higher temps than your WFO will reach, so they are then ineffective. Best to use the homebrew IMO.

[C5dad]

I am one of the guilty for using sand - I for one have not had any problems with it and feel it is serving me well. Reason I used it was the fact that getting bags of fire clay is a pain since very few here in the desert SW have fireplaces. I have to drive an hour to get a flu liner if the local masonry shop does not have them in stock.

CW

[Poetryart]

Next question. The FB board arrived and it's a softer material than I expected. Do I : 1. cut it to fit the INSIDE of the pizza oven so that only the floor of the oven sets on it?
or: 2. let it overlap the 36" interior allowing the bricks for the dome to sit on it?
If it's #1, then do I cut the floor firebricks to fit the same foot print, putting the soldier course outside of it entirely?
Our hearth is only 54" by 60", will it be a problem to make it an inch or two closer to the back edge, so that I can have a bigger landing? That means that for about 3 or 4 inches across the back, the insulation layer of concrete will be slightly thinner that other places.
Thanks! ~ Shelley

[mrchipster]

Originally Posted by Poetryart

Next question. The FB board arrived and it's a softer material than I expected. Do I : 1. cut it to fit the INSIDE of the pizza oven so that only the floor of the oven sets on it?
or: 2. let it overlap the 36" interior allowing the bricks for the dome to sit on it?
If it's #1, then do I cut the floor firebricks to fit the same foot print, putting the soldier course outside of it entirely?
Our hearth is only 54" by 60", will it be a problem to make it an inch or two closer to the back edge, so that I can have a bigger landing? That means that for about 3 or 4 inches across the back, the insulation layer of concrete will be slightly thinner that other places.
Thanks! ~ Shelley

All heated material needs to sit on the insulated board. And concrete is not insulating material so I am not sure what the insulating layer of concrete refers to.

Chip

[emsoven]

i used a layer of sand over my vermiculite floor cheep and works fine my floor is as flat as as my drive way there is no real need to use clay

[Poetryart]

I'm installing the soldier course first thing in the morning, question: do I put it ON TOP of the hearth, or outside of it? In reading the various posts, I'm really confused, do I worry about expansion of the hearth floor cracking my dome, or, if it sits on top, will everything move independently? I borrowed a wet saw and am ready to go. Please help! Thanks!

[cobblerdave]

Gudday
Don't be.... you can do it either way and yu'll still get the slip between the dome and hearth. When I did mine the thinking was the first course sat at the side of the hearth so you were able the change hearthbricks if needed. Guess what no one seems to need to change hearthbricks so current practice is the dome sits on the hearth. Makes for less cutting of the hearth brick so thats good

Regards Dave

[Poetryart]

Excellent! I'll get to work.
Next question: What happens if, after the dome is in, we surround the outside of the dome hearth with concrete to make the concrete under the hearth level with the dome floor? We haven't removed the wood form from pouring the hearth yet and could easily add to it. This would make everything nice and neat and easier for the decorative stone application. We're planning to stucco the dome after the fb blanket. There's a layer of concrete between the fb blanket and the stucco, too? Right? Hope this makes sense. :

[Poetryart]

Oh, one more thing, tell me if this is a dumb idea... I want to make a unique flue, but it won't be ready for a few months. Can I put a simple metal flue in and then just build the new one to slip around it? I'm a sculptor and can't do anything the ordinary way.... Wouldn't it be fun to make it a dragon blowing smoke or a gargoyle.? Or a woman's head and the smoke comes out her ears? Ha ha. I'd make out of terra cotta and glaze and fire it. Any suggestions on what it could be?