Insulating Fire Brick

[mazzazza]

I have just finished the base for my pizza oven and poured the reinforced slab, and have a question about the insulation layer:

I have 90 of what I think are insulating fire bricks (They're very light weight, and orange in color). Can I use these to make the insulating layer before I lay the hearth fire bricks or is a layer of vermicrete better?

Should I use the insulating firebricks for the chimney?

Is there anything else in the oven build that these would be suitable for? I have 200 pizza oven firebricks for the oven floor and the dome.

[david s]

They sound like they could be insulating firebricks, but “very light weight and orange in colour” is no guarantee. I’d be asking some questions from whoever you sourced them from. It is possible they’re not refractory and designed for building insulation use. The advantage of insulating firebrick over vermicrete is that there’s no need to drive out the water as they’re already dry.

[mazzazza]

Thanks for the response. All I know is I was told they're from a large industrial chimney that was demolished. The sides taper in very slightly so if you laid them side by side they'd eventually form a (very large) circle.

Do you know of any way of testing insulating properties?

Cheers,

Chris

[mazzazza]

That's a good point. They aren't dry per se as they've been kept outside, but presumably they won't absorb water to the same extent as vermiculite does.

[mazzazza]

Here is a photo of a brick split in half. It cuts extremely easily with a hand saw.

I also tried putting this piece on the gas hob for ten minutes and on turning it off the top surface was barely lukewarm.