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PlanoPhil 04-12-2011 05:31 AM

Insulating Casa90 Dome
I'm going to be installing a Casa 90 very soon and I'm a little confused about the process of covering the dome. The instructions that FB supplies say nothing about applying a layer of insulating concrete between the insulating blanket and the stucco however I have read many posts here that talk about that very thing. Is it necessary to add that additional layer. I live in North Texas and we do have cold snaps but it's not the frozen tundra.


HeidiL2011 04-12-2011 08:53 AM

Re: Insulating Casa90 Dome
Hi guys,

James here. There are some common misunderstandings about oven mass and insulation thickness.

It is true that a well insulated oven retains heat better than a poorly insulated oven -- because a poorly insulated oven loses heat through the insulation to the outer world. But all of the Forno Bravo ovens are well insulated, so adding more insulation to an oven with the mass of the Giardino would be overkill. It really would add very, very little benefit. As a general rule, ceramic insulation is roughly twice as efficient as loose vermiculite insulation. So if you calculate that in the past many ovens were insulated with 4" of vermiculite, you can see that the 3" of ceramic insulation that comes with the Giardino does a much better job of insulating the oven in less space.

The question of oven mass also comes up. In general, the heavier/thicker the dome, the longer the oven takes to heat up and the longer it retains heat (although the quality of the refractory also helps with heat up time).

I hope this helps.


PlanoPhil 04-13-2011 10:08 AM

Re: Insulating Casa90 Dome
Thanks James

Now to another issue. Did the stucco experts here ever come up with a consensus on:
  1. Best brand/formula to use
  2. Best way to apply color (paint/stain etc.)
  3. Waterproofing

Paul in Rockwall TX 04-13-2011 10:38 AM

Re: Insulating Casa90 Dome
Hello Phil,

I bought a bunch of TXI spec mix scratch & brown, as they call it. It's a preblended ready to use product available in 80 LB bags. I'm going to start with it this weekend, and I'll let you know. Got it at GARTEX on plano road.

Here's a link to their tech sheets.

SPEC MIX Products | TXI :: Innovating Standards

I'm not as concerned with waterproofing because I have a house enclosure and I'm only using it on the walls, but I intend to finish it with an old-school whitewash, but I'm not sure that's appropriate for an igloo final finish.

JamieC 05-24-2012 11:49 AM

Re: Insulating Casa90 Dome
I don't quite understand your response, James. I'm building a Giardino 70 (igloo style), and my instructions say to apply a 1/2-3/4" layer of insulating concrete before applying a 1/4" layer of stucco. Phil seems to be asking about what to cover an igloo with (on top of the insulation blanket)--are you saying to just use "regular" 2-coat stucco and skip the insulating concrete (AKA vermicrete)?



david s 05-25-2012 02:53 AM

Re: Insulating Casa90 Dome
Apart from insulating the vermicrete will help you get a nice even hemispherical form because overlaps and folds in the ceramic blanket leave a less than ideal uneven surface to apply the stucco to. Suggest you contact FB directly if you don't understand their instructions. forum members opinions may differ from those of the manufacturer.

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