Stucco or vermiculite mix on top of blanket

[mandrion]

Hi All,


I about to insulate my dome on my oven. I plan to put down a layer of the FB insulating blanket but not sure what to cover with. Is the recommendation to use a vermculite mix (if so what is the recipie) or use stucco to cover the insulating blanket?

Any help would be appreciated

Thanks,
Mike

[SableSprings]

Re: Stucco or vermiculite mix on top of blanket

When I built my oven, I put a layer of diatomaceous earth for slip/fill and then chicken wire (aka -hardware cloth) as a base for 5:1 perlite/cement insulation cap over the completed dome. In this forum, I've seen 8:1 noted as well. The FB insulating batts were not in my price range at the time. Even with the batts (and they are great!) consider having an extra layer of insulation/support like a perlite (or vermiculite) and cement combo over the dome. It's really worth a little extra cost and effort.

This last summer (2011), I helped a friend who was installing a Casa90 in Canada. We laid long sections of chicken wire under the hearth insulation boards. We assembled the oven and then pulled/joined/secured the chicken wire up & over the insulating dome batts. Next step was to put a layer of stucco mortar base (waterproof we were told) over the chicken wire and then scratched the mortar base surface for the upcoming stucco. After we'd let that layer harden, we started the curing process. After a week or so, we added two layers of stucco for the final coating. This modular oven is at a cabin in a somewhat arid section of Canada (Hihium Lake - NW of Kamloops, B.C.) so it will have a winter tarp covering, but summer will be exposed. Hopefully the waterproof underlay of the stucco will keep the insulation batts from picking up moisture during longer periods of inactivity at the cabin.

I've put a series of pictures below to help show what we did at the Big O by Hihium Lake. (The last picture doesn't show the completed ash slot/dump and landing at the oven front that was added a couple months later.)

[mandrion]

Re: Stucco or vermiculite mix on top of blanket

Hi Mike,

Thanks for sharing the photo's and the great advice. I agree, I will put a layer of isulation before I chicken wire and stucco the dome. I have been using the oven already and I can feel the warmth of the bricks as I get it close to a 1000 degrees.

I'm fortunate to live in California and can use my oven virtually year round.

Again...Thanks for the help,
Mike

[sousar]

Re: Stucco or vermiculite mix on top of blanket

so what did you use over blanket as I'm at this step now and wondering the same?

[SableSprings]

Re: Stucco or vermiculite mix on top of blanket

As I noted in my reply to Mandrion above, we just put chicken wire over the oven's insulating blankets and applied stucco base mortar. The mortar was not wet enough to add significant moisture to the insulation batts and it went on pretty easily because we'd secured the chicken wire fairly tight over the dome. This shows pretty well in the pictures above...