About to lay floor bricks

[Wheels1974]

I have tried to lay my floor fire bricks on a insulated board (Cal sil) which is almost 1 inch thick.
Under the 1 inch insulated board is a 4 inch Refractory cement slab. I would prefer to lay the floor fire bricks on the (Cal sil) insulated board as it helps a great deal with keeping it all level, not to mention I have it already.

My query is should I first lay a 5mm layer of refractory cement mixed with water like a fondue and spread it over the (Cal sil) insulated board, then lay my floor fire bricks on top?

Or should I just add a little dry refractory cement on the (Cal sil) insulation board and lay the floor fire bricks evenly on top?

Or should I lay the floor fire bricks directly on the (Cal sil) insulated board?

I have already tried doing it with the refractory cement and mixed it with water till I got a fondue mixture but as soon as I put the wet refractory cement mix on the (Cal sil) insulated board, the wet mix goes dry immediately.

What is the right way of laying the floor fire bricks on the Calsil insulated board?

Any advise would be appreciated.

Regards
Wheels1974

[ThisOldGarageNJ]

My query is should I first lay a 5mm layer of refractory cement mixed with water like a fondue and spread it over the (Cal sil) insulated board, then lay my floor fire bricks on top?

If you would like to do it this way , make your slurry in a bucket. and butter your bricks seperately as you lay them down,, a very fine butter shoud do well... Mostly you only want to do this just to level out your floor.. I built my dome on top of the brick, this encsures that the weight of the dome holds the floor in place as well..

And if you do have ny bricks that ar euneven, they can always be sanded or ground down...

Cheers
Mark

[Wheels1974]

Thanks Mark,
We are also building our dome on top of the floor fire bricks. How did you lay your floor bricks, did you use a refractory mortar to stick your floor fire bricks to the bottom?
Did you use Cal sil insulated board? Or a Insulated cement mix below your floor bricks?

Regards
Wheels1974

[ThisOldGarageNJ]

Hey Wheels,,

did you use a refractory mortar to stick your floor fire bricks to the bottom?

I Had 4 inches of vermicrete under the floor bricks.. It wasnt too level so i used a premix refractoy cement for boiler repair (usually not recommended) it was an air set mortar... I buttered each brick with a thin coat and more or less if needed to level them out.. they set down hard as a rock after a day or to, to this day they dont move or wobble. but the ash that compacts between them also holds them in place.. (the reason most dont use the premix is that it can be water soluble)

I then Built my dome on top of the fire brick floor... the weight of the dome wont let it move... I put some pics below to give you an idea,,,

Cheers
Mark

[dmun]

Just as a note: Cal-sil, unlike the more common mineral fiber refractory insulation board, does have a tendency to suck up water. You may be better using your leveling medium dry. You may not need a leveling medium at all. A lot of us have laid our floor bricks directly on the insulation boards.

Also: Do you have any underfloor insulation other than the cal-sil board? Is the refractory mix under it an insulating castable product? The reason I ask is that one inch (25mm) of insulation board is about half what's recommended. There's no time like the present to make sure your oven has proper insulation under the floor: There's no going back once your dome in built.

Insulate! Insulate! Insulate!

[Wheels1974]

Originally Posted by dmun

Just as a note: Cal-sil, unlike the more common mineral fiber refractory insulation board, does have a tendency to suck up water. You may be better using your leveling medium dry. You may not need a leveling medium at all. A lot of us have laid our floor bricks directly on the insulation boards.

Also: Do you have any underfloor insulation other than the cal-sil board? Is the refractory mix under it an insulating castable product? The reason I ask is that one inch (25mm) of insulation board is about half what's recommended. There's no time like the present to make sure your oven has proper insulation under the floor: There's no going back once your dome in built.

Insulate! Insulate! Insulate!

Dmun,
Thanks for your reply mate. We first made a 4 inch foundation of concrete and Rio for structural support just as the FB instructions recommend.
After about 3 weeks, we then poured another 4 inch of Refractory mortar (SHERLITE) on top of the standard concrete Rio slab.

Regards
Dean

[Wheels1974]

I almost forgot the Cal-cil we have has obvioulsy been wet due to us trying the soft refractory mortar which didn't work so there are parts of the Cal-cil board that we hosed down to clean it up. Does wetting the Cal-cil board matter at all?

Regards
Dean

[Wheels1974]

Originally Posted by ThisOldGarageNJ

Hey Wheels,,
I Had 4 inches of vermicrete under the floor bricks.. It wasnt too level so i used a premix refractoy cement for boiler repair (usually not recommended) it was an air set mortar... I buttered each brick with a thin coat and more or less if needed to level them out.. they set down hard as a rock after a day or to, to this day they dont move or wobble. but the ash that compacts between them also holds them in place.. (the reason most dont use the premix is that it can be water soluble)

I then Built my dome on top of the fire brick floor... the weight of the dome wont let it move... I put some pics below to give you an idea,,,

Cheers
Mark

Mark,
Thanks a TON for that info and those photos mate, it looks great.
I took Dmun advice and we are laying the floor fire bricks directly on the
Cal-cil and using a little dry refractory mix where needed to make the floor bricks as level as possible.
I could of done what you done also Mark as I have 4 inches of refractory mortar below this Cal-cil board, but I already had the Cal-cil board here so I thought I may as well use it. As they say you can NEVER over insulate.

Regards
Dean

[ThisOldGarageNJ]

Dean,,
No problem.... as we say here.... you can never over build, over insulate....

Cheers
Mark

[dmun]

Does wetting the Cal-cil board matter at all?

It shouldn't. Cal-sil is the most stable of the insulating boards. All your insulation material will get more or less wet as you build your dome. It will dry out as you cure and dry your oven.