Fibre board hearth insulation.

[Crusty]

I'm building my oven with stuff I have laying around (budget non-existent)
and I happen to have 3 insulating fibre boards laying around.

I have two of these: Promatect H that has 0.21 W/mK at 200?C and is 25mm thick.
(http://www.promat-ap.com/pdf/HTI_TE38_500.pdf)

the other is Promafour that 0.185 W/mK at 200?C 20 mms thick.
(http://www.promat-hti.be/files/cms1/...OUR%20(EN).pdf)

I'm building a low dome Neapolitan oven and plan on running it mighty hot. (and both brand claim to be "shape and dimensionally stable up to 400 ?C")

I guess my question is threefold:
1. Are these the right boards for insulating my floor?
2. Which one?
3. Since I have 'em and I'll probably get rid of the ones I don't use, is there an advantage to be had by using two of them stacked together?


Any help is greatly appreciated!

[cobblerdave]

Re: Fibre board hearth insulation.

Gray Crusty
This is a hard one to answer as probably no one has used this insulation before.
I can't say myself but if I was considering this insulation would it take the weight of the oven firstly.
Secound could it take the heat that an oven can produce , which is about 500C so your best to have something that should handle 650C.
If it can take the weight great. If it is a bit low on the temperature side and funds are tight you could use it as a secondary insulation layer protected by a higher rated insulation layer. From what I read its rated at 400C which is a little low.
Sorry for being carful with my answer as its pretty hard to replace after your oven is finished.
Regards dave

[Crusty]

Re: Fibre board hearth insulation.

Thanks for the answer.
I'm prettty sure they can take the weight, they are hard, heavy and lay flat on a concrete slab so where are they gonna go? And both are calcium silicum boards, which a lot of people on here are using.
Anyway, I already layed down the thicker one and cut it to shape, I'll see if I can find something else to put on top of it free or cheap, otherwise I'm using the second board I guess.

[cobblerdave]

Re: Fibre board hearth insulation.

G'day
Use the other board as well you can't have to much insulation. If you can get pearlite or vermiculite mixed with Portland cement 5 to by volume. A couple of ins should protect things. You can usually find this as a soil conditioner and as a hydropics medium.
Regards Dave

[Crusty]

Re: Fibre board hearth insulation.

Thanks, instead of that I used blocks of Ytong of 7 cms thick on top of the concrete and under the boards, they cost next to nothing. Should do the trick.