Insulation Aircrete

[aaronnielsen]

Has anyone tried doing a vermiculite aircrete for the under hearth insulation?

[UtahBeehiver]

Thread moved to Oven Construction. FYI, The oven hearth needs for be a rebar reinforced concrete mix to support an oven, not a vcrete mix.

[aaronnielsen]

Not talking about the hearth itself. Can aircrete be used for the insulation between the hearth and oven fire bricks?

[Gulf]

david s experimented with someone home made aircrete a few years ago.

[UtahBeehiver]

I guess I misread your question, it said under the "hearth" insulation. Some builders in Australia have used Hebel which is an aerated concrete panel. What are you meaning vermiculite aircrete. Have you downloaded the eplans from Forno Bravo? It is a good baseline for design and construction of WFOs. Also, here is table showing vcrete that is commonly used on WFOs.

[david s]

Aerated concrete can be used as underfloor insulation, but it’s only about as good as a 4:1 mix of vermicrete. Nowhere near as good as cal sil board. When I built my first mobile oven, I was trying to keep it as light as possible an I used it (Hebel) as both an insulating later and supporting slab. Hebel provide a product called power panel which is the same density as the standard stuff, but has 5 mm steel reinforcing cast into the centre. It failed, but I’m still not sure if it was from the heat or road bumps. Used between a reinforced concrete supporting slab and the floor bricks, it would be ok, but not the best insulator. I think it’s only around 70mm thick which for its density is really not enough.

[aaronnielsen]

I was thinking an Aerated concrete which also contains vermiculite. I guess if that is no better than a 4:1 mix of vermicrete then maybe not worth it.

[WoodywWun]

I picked up in a thread that Thermalite blocks were being considered. I checked out the thermal conductivity and 100 mm Thermalite Turbo blocks compare well with vermiculite concrete with a U value of 0.11 W/mk compared to 0.17 W/mK for vermiculite concrete. I'm no thermal engineer but I'm checking out the suitability with the manufacturer. Thermalite blocks would work out cheaper than vermiculite concrete. Would they be stable under heat? Don't know!

[david s]

Has anyone tried doing a vermiculite aircrete for the under hearth insulation?

Another alternative is foamcrete. I did some experimenting with this stuff and it has some advantages. Unfortunately combining vermiculite with the foam results in it deflating a fair bit, so you end up losing volume. While it is a fair bit cheaper than vermicrete it takes longer to make because you have to generate the foam first and mixing it in to get a homogenous mix takes time and overdoing it results in some deflation.
Check it out here.https://community.fornobravo.com/for...rete#post16031

[WoodywWun]

I checked out the suitability of Thermalite blocks with the manufacturer (Forterra) and they say that Thermalite blocks are not reccommnded to be used on their flats as they have not been tested, structurally like this. I don't think that this is an issue in the WFO world. However, they also said that the blocks are not reccommnced to be used next to fire as they may crack. Unless someone who has used them has some experience with Thermalite blocks, it's the end of the road for me using them on my build, I think.