Igloo style dome insulation

[Throw Deep]

Re: Igloo style dome insulation

H Guys, I want to find out if need a Ceramic Fibre roll insulation around my Dome. The cost is twice that of Rock Wool. Can I use rock wool instead and then put a 4" layer of vermiculite?

I don't know anything about Rock Wool. I used the Ceramic Fibre and it has worked very well. I added about 3-4" of vermiculite concrete mix and after firing it a few times to dry it all out, I hired a pro to finish it with stucco (i had another stucco job going at the time).

[Hugoagogo]

Re: Igloo style dome insulation

Thanks for the quick reply......It isn't domestic insulation. It is made from spun volcanic rock and has a burn temp of about 1000 deg c. It is much thicker and denser than standard fibreglass insulation. Also, I am intending to also put 4" of vermiculite on top of the insulation. If it is too risky, I'll just get the ceramic fibre. I don't want to risk it not holding heat for a hundred dollars less.

[Throw Deep]

Re: Igloo style dome insulation

"Sounds like I'll just have to "free hand" the shape of the igloo...wish me luck."

Or you can build a jig that you can rotate as a screed, like this:

Whew...that jig is beyond me. I sort of free handed it but used the round shape of the dome to my advantage. Since it was already rounded I cut a wire clothes hanger into 5" lengths and then bent the ends at about 90 degrees where I had 6 or 8 pins that were 4" long with a "handle". As I built up the vermiculite/concrete mixture I stuck a few of those pins around the dome until they were seated against the brick dome. It showed me how much vermiculite mix to add and when I needed to reduce a little. When I was satisfied with a section I pulled the pins out and moved on. I pressed the small hole shut...but the holes seemed to close in as I pulled the pins out so there was probably no need to worry about the pinhole. After working all around the dome the end product looked pretty good. When when the stucco went on it produced a very round and nice looking finish.

We had pizza tonight. Good times. Very cool.

Good luck.

[Frances]

Re: Igloo style dome insulation

Thanks for the quick reply......It isn't domestic insulation. It is made from spun volcanic rock and has a burn temp of about 1000 deg c. It is much thicker and denser than standard fibreglass insulation. Also, I am intending to also put 4" of vermiculite on top of the insulation. If it is too risky, I'll just get the ceramic fibre. I don't want to risk it not holding heat for a hundred dollars less.

I ended up using some sort of rockwool - its all that I could find around here. But it was a product developed specifically for insulating heatings and ovens etc. and luckily it works very well... (with an added layer of vermiculite).

So I'd say it depends on the kind of rockwool you're talking about. Remember that it won't have to stand that kind of temperature only once but again and again and again. Maybe call up the company that produces it and ask if they'd recommend it?

[Neil2]

Re: Igloo style dome insulation

"and I don’t like the idea of trapping all of that water under the stucco."

I suggest initial curing before the stucco application. The oven will expand a lot but will not fully contract after the first firings.

As to driving the water out, I put a vent on the top of the dome that communicates thru the stucco layer into the insulation layer. I also put four small (1 inch) vents at the bottom around the perimeter. This allows any residual moisture to escape and allows the insulation layer to "breath" thus keeping it dry over the long run.