Fire Brick Thickness

[RossSA]

Hi All,

I am busy palnning my refactory cast WFO, and am sourcing the fire bricks for the base. I can source 3in and 1.5in thick fire bricks, the price of the 3in bricks is double the 1.5in brick price.

Any thoughts on saving costs to go for the 1.5in bricks? I know the thermal mass will be halved, but if the wall thickness of the cast dome is also in the range of 1.5in will it influence the operation of the oven?

[deejayoh]

Re: Fire Brick Thickness

Ross -

The majority of the ovens built of bricks on this forum are 4.5" thick in the dome, and 2.5" thick in the floor. The bricks are cut in half and set flat. It would be good to know the other dimensions of the bricks you are considering in order to better answer your question.

[RossSA]

Re: Fire Brick Thickness

They are 230x114x76 or x38 mm (9x4.5x3 or 1.5 in).
Thanks

[deejayoh]

Re: Fire Brick Thickness

I would recommend the 3" bricks then.
- A bit more thickness laid flat on the floor gives you more thermal mass.
- 3" is not so thick that when building the dome that it would make it difficult to get the right arc
- added bonus is that you'll have ~15% fewer courses of bricks to lay because each course is thicker than a normal build!

[GianniFocaccia]

Re: Fire Brick Thickness

If the bricks are the same cost per exposed-sq", it's obviously less work (and mortar to go with the 3" bricks.

If you decide to go with the 1.5" bricks (splits), you will have the opportunity to construct a top-flight oven. Personally, I think ovens built with thin bricks make for a very handsome oven. And remember, thin bricks cut easier and faster.

Here's a previous look into thin bricks:

http://www.fornobravo.com/forum/f6/w...ick-17446.html

[david s]

Re: Fire Brick Thickness

Not only that, an oven that is thinner will heat faster and use less fuel to heat it. Most cast ovens are pretty thin, around 2". If you use the 1.5" bricks for the floor and you want to increase the floor thickness you could lay a 1" slab of concrete containing plenty of lime, between the insulation and your 1.5" floor bricks. That would bring the floor to 2.5" and you can then cast your refractory dome to the same thickness.

[RossSA]

Re: Fire Brick Thickness

Thanks, all. It appears the general opinion is to go for a higher thermal mass floor. IMO it might be easier and quicker to go for the thicker bricks and skip the extra slab to increase the thermal mass of the thinner bricks.

The other option is to cast the floor with the same material used for the dome (to the same thickness?). Has any one had experience with this? or is there a fatal flaw that I have not found on the forum yet?

So its back to the drawing board for now with yet another design revision. Design drawings to follow soon!

[deejayoh]

Re: Fire Brick Thickness

There are a number of cast domes on the forums. Some cast on sand, others cast in forms. Do some searching, I am sure you'll come up with examples. I don't know what the +/- is from a performance standpoint. But most of the builders on here went with bricks if and when you are looking for help!

[david s]

Re: Fire Brick Thickness

The other option is to cast the floor with the same material used for the dome (to the same thickness?). Has any one had experience with this? or is there a fatal flaw that I have not found on the forum yet?

!

If you cast the floor in castable in one piece it will crack. You can get away with it if you cast a number sections, but if you already have the fire bricks for the floor you'd be better off using them.