Roxul Insulation safe behind firebricks in an arch?

[Maplesapper]

Can I line the inside of my arch with Roxul Rock Wool Insulation, and then sandwich it with firebrick.
The firebrick would be held with mortar, so I do not believe any fibers would get free.

Safe or Not Safe, and a brief explanation would be great guys....

[Foremaple]

It would be a great testimony for Roxul. I would definitely experiment on something other than your arch prior. I would love to hear how it turns out though.

[jmayerl]

Well there spec says 2150F and the density is 2lbs/sq ft. The only problem I might see is that it relies on not being totally compressed for its insulation factor. Ceramic blanket is rated 2300F and I think 6lbs/sq ft. I would say give it a try if it's considerably cheaper.......then again it isn't my arch

[maple flats]

If it doesn't get totally compressed it should be OK. It is not combustible.

[killingworthmaple]

I used it behind brick in the past with great results. Go for it!!

Nathan

[maplestudent]

Maplesapper.....have you tried the Roxul Rock Wool Insulation? I'm thinking about trying it in my barrel arch.

This is what their website lists under fire resistance:

"Its unique composition won't burn, or release toxic gases or smoke when exposed to high heat. And it can withstand temperatures of up to 2150˚F (1177˚C) – well above heat levels of typical house fires. "

a package of 12 batts, 47" x 15" x 3" thick is about $36 at Lowes.

[Maplesapper]

Just ran with 2" firebrick.
Turned out it takes up too much room, and caused problems with the configuration of the bricks.

Couldn't find any concrete info to alleviate my concerns about loose fibers.
So firebrick and refactory cement it is.