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johnfm43 07-28-2011 09:17 AM

Floor Insulation
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I have run into a problem. I poured my hearth insulation and concrete yesterday. When I removed the boards, somehow I only have 2 1/2 to 3 inches of Vermiculite layer. I know that most have talked about a 4" layer. Has anyone used their oven with a 2 1/2 inch thickness of insulation? What is the major draw back for this screw up.

I would pour more or purchase some FB board insulation except my Floor height is 47" already using 2 inches of board will obviously bring it up to 49". My wife is only 5'4" and I am already concerned about the height of the floor. HELP.

SCChris 07-28-2011 12:34 PM

Re: Floor Insulation
Insulation is your friend and more on the floor is better. I’d look at if you can either step up where you stand or bring the whole patio area up. It looks like what you have is waiting to have a patio slab poured. Is this correct?


brickie in oz 07-28-2011 01:21 PM

Re: Floor Insulation
Dig it out and replace it with calcium silicate board, the board has more insulating properties than vermicrete. :)

Im not a fan of vermicrete to start with, all that effort when you can just buy a board to plonk down and its done. :D

johnfm43 07-28-2011 01:32 PM

Re: Floor Insulation
No actually my slab is already poured. Is tearing it out and using board the only solution I have. What is the problem with only 2 1/2" under floor?

brickie in oz 07-28-2011 01:46 PM

Re: Floor Insulation

Originally Posted by johnfm43 (Post 118038)
What is the problem with only 2 1/2" under floor?

They recommend 100mm and it must be for the minimum amount, more obviously would be better.

Yet 40mm of board does the same job, Ive got 40mm of board under my oven.

I actually think the vermicrete would work out more expensive in the end compared to using a board.

Anyone done comparisons in price? :confused:


Originally Posted by johnfm43 (Post 118038)
No actually my slab is already poured.

But you will only be taking out the vermicrete, not the concrete.

Les 07-28-2011 01:50 PM

Re: Floor Insulation
Can you compromise on the height and add just one inch of board. The result would be better than 3 1/2 of vermiculite. Or add the 2 inches and buy your wife some cooking pumps...

turkey 07-28-2011 01:51 PM

Re: Floor Insulation
do you already have 2" of FB board? or thinking how high it would be with it?

RTflorida 07-28-2011 01:58 PM

Re: Floor Insulation
less heat retention.
If you are only planning to use it for pizza with a fire off to the side, you should be able to maintain the desired temps. You will probably have issues with bread baking and roasting. Too little insulation leads to more rapid bleed off of the heat retained within the bricks, which in turn will cause a more rapid cool down within the oven.

Best to stick with a known and proven plan = at least 2" of board or at least 4" of perlite/vermiculite concrete.

There have been many threads from those who have stumbled upon this forum after they or "a friend who builds ovens" have completed their ovens with too little, wrong materials, or no insulation. To fix after the fact is extremely problematic and many times ineffective. You are at a point where correcting the problem is not much work and not too much of an expense.


RTflorida 07-28-2011 02:04 PM

Re: Floor Insulation
I think Les offers the best compromise, add 1" of board. No chipping out whats there, just lay the board and move on. Even for you wife, that 1" in added height isn't going to be noticeable, unless you tell her things are taller than planned.


johnfm43 07-28-2011 02:27 PM

Re: Floor Insulation
I do not see 1" board for sale on their website. Can some one direct me to the link.

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