Will this work for under oven insulation

[Greenman]

Re: Will this work for under oven insulation

A 4 inch layer of vermicrete sounds about right. No overkill there.

That is what many of us have used. Your are on the right track.

[dakzaag]

Re: Will this work for under oven insulation

what is the purpose of the middle layer of firebrick?



2" FB board would be enough. 5" vermiculite would be plenty.

[cook4fun]

Re: Will this work for under oven insulation

In all the reading, it seems that the biggest "post construction" wish list was that they wished they had added another layer of insulation between the vermicrete and the calsil board.

Happy to learn the finer points of insulation...once it's built...can't raise it up to add more !

[NCMan]

Re: Will this work for under oven insulation

Hello everyone - love the free flow of ideas...I'd like some final planning guidance as I get ready as well...I'm planning on: finishing the concrete stand "topped" with a 4 inch layer of either vermiculite or perlite (4:1 ratio mixed with portland cement), followed by a layer of fire brick, followed by the FB insulation board...and on top of that the hearth of the oven.

I agree w/dakzaag regarding the firebrick layer. What is the purpose of the layer between the insulation layers? I'd skip that. Also, you may want to consider going either 1:6 or 1:8 on your perlite. The less cement you use, the better the insulation value. In addition, you may want to plan out all your layers to be sure the finished floor/hearth level is where you want it to be. My 2?.

[cook4fun]

Re: Will this work for under oven insulation

Thanks to all...the goal is to have the floor of the oven hearth at 52"

- oven hearth (2 inches)
- FB calsil (2 inches)
- 5 inch 6:1 vermicrete (or higher) on top of the concrete blocks...the distance from the top of the 6 inch reinf slab (on top of footers) to the top of the 5 inches of vermicrete will be 48 "

[karl]

Re: Will this work for under oven insulation

I recommend 10 cm porous concrete blocks/slabs under the oven on top of he structural table. It insulates very well and has very good compressibility resistance. It is way better than the self-mixed vermiculite.

[dakzaag]

Re: Will this work for under oven insulation

Karl brings up a great point. Vermiculite Portland has very little structure capabilities. In fact I was wondering what C4F had in mind to contain this layer as it will just squish out unless a perimeter is established.

Unfortunately the product Karl is mentioning is not readily available in the US. It is a little more available in the south, Florida and Texas both have distribution centers, but I am not aware of any retail locations. If you're interested in a full truck load, you can get whatever you want, but just a piece or two is a hard order to come by. You can get insulating firebrick from Kiln supply locations that are somewhat similar.

[RandyJ]

Re: Will this work for under oven insulation

So are you saying that the insulating fire brick are a ok alternative to to call board. I thought they were not much better that the vermicrete for the insulating capabilities?

Randy

[Gulf]

Re: Will this work for under oven insulation

......... Vermiculite Portland has very little structure capabilities. In fact I was wondering what C4F had in mind to contain this layer as it will just squish out unless a perimeter is established........

If allowed to cure, it shouldn't "squish out". It should be allowed to cure and then dry before being built upon. It will chip very easily at the corners if disturbed during the build, though. One way to prevent that is to leave the temporary form for the vcrete in place for as long as possible. That is what I did. But, there are plenty of builders that did pour their vecrete in a permanent form. In either case vecrete has plenty of compression strength.

Randy,
I am pretty sure that Dakzaag was saying that insulated fire brick were a great alternative to vecrete or pecrete. They would allow someone to skip the curing and drying time for that layer. CalSil or FB board is what a lot of us have placed on top of the vcrete or insulated fire brick Layer.

[dakzaag]

Re: Will this work for under oven insulation

Insulation is insulation as long as it doesn't compress. The vermiculite works fine, but you have to form it and then like Gulf says, leave the forms in place as long as possible. If you have access to cheap insulating brick, that would be fine as long as it can hold up the dome. I don't know how brittle the insulating brick can be.

I wouldn't be comfortable with some of the cast insulation under a mobile unit as it might compress from the road vibration, but other than that vermiculite just needs to be contained somehow.

Now to side track this thread, Karl, are you talking about AAC? I have a few pieces and I am playing around with it, but I need to know how structural it is.

[cobblerdave]

Re: Will this work for under oven insulation

G'day
ACC or Hebel, local product name is the insulation I've used under my oven.
I've been cautious to recommend it over the years because many members pointed out that being a cement based product it could be harmed by temperatures over 300C. 4 years and still cooking well, so I don't think its an issue. A lot of Australian builders also use the block and the steel re enforced flooring form to build thier entire oven stands. It's also used a lot in the UK oven builders because of price and availability.
Regards dave

[Gulf]

Re: Will this work for under oven insulation

Dave,

If there is a problem with AAC (Hebel), then there is a problem with Vermicrete and Perlcrete. The binder used in each of those is portland cement. A lot of what we choose to use to insulate our ovens is what is available. I have never seen an example of Hebel. But, from what I have read on this forum, I would not hesitate to use it. That is, if it was "easily and economically" available .

Take care...old friend,

Joe

[dakzaag]

Re: Will this work for under oven insulation

No sense in hi-jacking Randy's build, I am going to take this over to a new thread.

[Gulf]

Re: Will this work for under oven insulation

No sense in hi-jacking Randy's build, I am going to take this over to a new thread.

???? I can delete my posts on this thread, if this was considered a hijack . I did not know it was a build thread. I thought it was a topic for discussion under Finding Building Materials.

[david s]

Re: Will this work for under oven insulation

Dave,

If there is a problem with AAC (Hebel), then there is a problem with Vermicrete and Perlcrete. The binder used in each of those is portland cement. A lot of what we choose to use to insulate our ovens is what is available. I have never seen an example of Hebel. But, from what I have read on this forum, I would not hesitate to use it. That is, if it was "easily and economically" available .

Take care...old friend,

Joe

The disadvantage of vermiculite or perlite concretes is that they both make the final product that will wick water into itself readily. Also it takes time to eliminate the water from them once laid and cured and you need lots more water in the mix, unless you have access to the silicon coated variety(which i don't). Using aerated concrete has the advantage of not being as water absorbent. The main disadvantage with it is that it is expensive unless you make your own. Making your own is even cheaper than making vermicrete, but but requires more skill in mixing and laying.
See here

http://www.fornobravo.com/forum/f44/foam-concrete-18447.html#post139631