Duraboard vs Insboard vs FB Board

[blacknoir]

I'm wondering if there are any serious advantages/disadvantages to any of these insulation boards? I might have a local supplier for the first 2 which could potentially save me shipping costs but I don't want to save a little money on an inferior product.

Thanks,
Shay

[jpar]

Duraboard, Insboard 23 and FB Board are all ceramic fiber boards. Duraboard and Insboard are made in the USA, FB board is made in China.
Insboard 19 is mineral wool based.
All of these boards are made of fibers and binders, the binders will burn off at temperatures over 450 deg F, leaving behind a board that does not have any strength. I prefer using Super Isol cal sil board, which will retain some strength.

[dmun]

the binders will burn off at temperatures over 450 deg F, leaving behind a board that does not have any strength.

I don't think this is true. In years of building with insulation boards, we've only had one collapse, with a board not cited above, and that was moisture related, not a heat failure.

Refractory boards are designed to bear weight, whether they are cal-sil or mineral wool based.

[jpar]

Duraboard / Insboard / FB Board are not structural insulations designed to support much weight. Will they work in a sub hearth application? Yes, they will insulate, and they will provide some support, but this is not the function for which they are intended.

Regarding burn out:
here is the link (from the manufacturer) that discusses burn out: Unifrax.com

[egalecki]

The guy at Harbison-Walker sold me the Ins. 19 last year, knew what I was using it for, and said it would be fine. It has been. I have it under my floor, and my dome sits on top of the floor, not around it.

I have no structural issues at all other than my own mistakes, which have caused a few cracks.

I'm with Dmun.

[Ken524]

Originally Posted by dmun

I don't think this is true. In years of building with insulation boards, we've only had one collapse, with a board not cited above, and that was moisture related, not a heat failure.

Sounds like me ! And even my crappy board seems to be working quite nicely now that everything's dry.

[PerryPizza]

I have just acquired some insulating board but don't know what sort it is (it's white, 5cm thick x 35cm wide) - but it seems very soft to be supporting an oven so I'm not sure I'll use it in my build - I can dent it quite easily with my fingers... is this normal?

[dmun]

I have just acquired some insulating board but don't know what sort it is (it's white, 5cm thick x 35cm wide) - but it seems very soft to be supporting an oven so I'm not sure I'll use it in my build - I can dent it quite easily with my fingers... is this normal?

Is it a refractory material? There are a lot of foam panels out there that you wouldn't want to take much over room temperature. I'd think twice before using mystery foam in a high heat situation.