Insulation layers- Hello from Carolina Coast

[RandyL]

I planned on 2 layers of FB blanket over my completed dome, followed by a perlite-Portland layer about 1.5” thick to lay my external shell decorative bricks into.

A] Is there any reason I couldn’t just use a chicken wire mesh over the blankets to cover with the insulation mortar layer? I’ve read in this forum 1/4” screen before stucco… but for thicker perlite-Portland mortar would that be needed? Chicken wire would be easier to work with IMHO

B] Anyone anticipate a problem setting my standard bricks into the wet perlite-Portland layer? (I would mortar the brick joints with standard mortar, or the fire clay mix if that’s recommended) When I built my oven floor I used my insulation perlite layer to tamp fire bricks level using paper towels beneath to prevent adhesion. Worked great.

For the outter dome I’d actually want the adhesion of the insulation layer. Am I missing anything?

[SableSprings]

Welcome to the forum community! The chicken wire will help when applying the insulating perlcrete layer but it is kind of a pain to put in place over the batting. Should reduce batting compression and give the perlcrete some attachment base. Cutting wire section wedges to pull up from the base to the dome top seems to be the logical approach, using wire ties to hold the sections together. I created a barrel outer shell shape over my dome's perlcrete using regular bricks and after 12 years everything is still solid (note my oven does have a roofed cover ).

No matter how simple it may seem to work with applying the chicken wire to the dome, be aware that it will be a pain in the a** as the cut wire edges are sharp & the wire seems to have a mind of its own on how it should lay! Be patient, wear good gloves, and get somebody to help you...holding a wire section in place while trying to cinch up a wire tie by yourself would make for a good, short comedy video (imho).

[david s]

Welcome to the forum community! The chicken wire will help when applying the insulating perlcrete layer but it is kind of a pain to put in place over the batting. Should reduce batting compression and give the perlcrete some attachment base. Cutting wire section wedges to pull up from the base to the dome top seems to be the logical approach, using wire ties to hold the sections together. I created a barrel outer shell shape over my dome's perlcrete using regular bricks and after 12 years everything is still solid (note my oven does have a roofed cover ).

No matter how simple it may seem to work with applying the chicken wire to the dome, be aware that it will be a pain in the a** as the cut wire edges are sharp & the wire seems to have a mind of its own on how it should lay! Be patient, wear good gloves, and get somebody to help you...holding a wire section in place while trying to cinch up a wire tie by yourself would make for a good, short comedy video (imho).

Sorry Mike, I can't agree with the advocating of chickenwire over the blanket layers. After abandoning chickenwire to hold down the blanket for the very reasons you've given and the time that it takes, I abandoned its use many years ago. If a thick (around inch and a half) lean vermicrete layer is built over the blanket it adds insulation, corrects unevenness in the blanket layers and provides a firm enough substrate to render against. It does virtually nothing to strengthen the vermicrete layer when a very lean mix is used anyhow. There is also a tendency for the chickenwire to compress the blanket thereby reducing its insulation value. Also a highly conductive material like steel, although there's not much of it, is not suitable in the middle of a layer that's designed to be highly insulative. I've built hundreds of ovens since abandoning chickenwire and have never regretted the decision.
Attached are pics of an oven that had a varying number of blanket layers applied (two on the sides and five on top, because of the tight corner build, but no chickenwire.The outer render is a different story, but again, no chickenwire, random fibre reinforcing used instead.

[RandyL]

Thanks Dave & Mike for your suggestions. I actually like skipping the wire, but thought it was required for a good build

Dave what did you mean by “ no chickenwire, random fibre reinforcing used instead” what exactly is fibre reinforcing?