Igloo style dome insulation

[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.

[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?

[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.

[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

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).

[dmun]

Re: Igloo style dome insulation

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 think "rock wool" is down-underism for domestic fiberglass insulation. This has organic binders that will burn and stink. Stay away from this option.

If you're on a tight budget, use four inches of vermiculite concrete instead. The refractory blanket under it is good, but not required.

[Neil2]

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:

[Hugoagogo]

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?

[gjbingham]

Re: Igloo style dome insulation

Throw Deep - I've forgotten how much of a layer of vermicrete you're trying to put down outside your blanket. The chicken wire frame needs to be separated from the dome by that amount. The stuff is held in place by the wire. It will not stay in place outside the chicken wire (except on top of the dome).

It wouldn't hurt to wait a week after the vermicrete before firing, unless you're pretty sure that the insulation is cool to the touch. You don't want to rush the core or dry out the cement to quickly.

[arevalo53anos]

Re: Igloo style dome insulation

Some pictures about the process.

Luis

[Throw Deep]

Re: Igloo style dome insulation

Thanks for all of the great ideas on shaping the dome. At this point my blankets are on and the chicken wire has been shaped around it...not anchored in any way to the dome itself. So it is a floating shell around the blankets tucked in on the front between the blankets and the back and sides of the chimney. It is tight enough in some places where it won't move but in others there is an inch or so between the wire and the top blanket. I don't think that packing on the vermicu-crete is going to move it. Hopefully that will be okay.

I think I might cut a straight piece of coat hanger wire and try to see if it will penetrate the blankets and seat against the dome for a depth guage. Perhaps the 3" blanket layer will hold them in place while I put the vermicu-crete on. If not, I'll do the walk around eyeballing method.

So, once I get the vermicu-crete on there, I'll let it cure for a week or so and then let the scratch coat of the stucco do the same. I don't suppose that fires during that curing period will have any impact one way or another?

Thanks.

Bob

[david s]

Re: Igloo style dome insulation

cvdukes,
I don't think coathanger wire is a good idea, its too thick and provides a path for heat to escape to the outside. I use thin wire about 0.5 mm twisted together with aloop at one end and some legs to sit flat against your dome. This is held in place by a layer of concrete and these wire ties act as depth guages for your vermiculite layer and as anchors for your mesh for your ferro cement outer shell. Works a treat.

[gjbingham]

Re: Igloo style dome insulation

My experiences - the less spherical you put the blankets on the dome, the more work you have to do to get it back to symetrical. I didn't do exceptionally well, but I can live with mine.

I wouldn't worry about the cure of the vermiculite too much. A week should be plenty. It will still be wet inside (I think it would still be moist a month later, based on my experience of cutting my vermicucrete insulation later 6 weeks after placing it), but the base coat of the stucco will help suck the extra moisture right out of it. Give that base coat a week or 10 days to cure/dry before placing a waterproof finish coat. CJim - disagree if you think otherwise. I'm winging it a bit.

Before going to the stucco though, you can always add more chicken wire/lathe to uneven areas and add more vermicucrete to get you back to round. Trust your eyes. Stand WAY back and walk around the dome. Irregularities are quickly obvious if you pay attention. Also, if you can find a vantage point from above, a ladder or roof, so that you can look down on top of the dome, you'll pick up minor problems that need work.

Hope that helps a bit.

[RTflorida]

Re: Igloo style dome insulation

cvd,
I used a wire coat hanger as my depth gauge, but not in the manner described; I merely put a piece of duct tape on the wire (at the 4" mark) and "poaked" it into the perlcrete at various points as I slopped it on.

the freehand approach is not as difficult as it seems...you get a feel for applying it pretty quickly, and as mentioned, any peaks and valleys can easily be addressed with you final render. Biggest thing to remember is to start at the base of the dome and work up, the chicken wire DOES help keep it in place as you pack it on.

RT

[cvdukes]

Re: Igloo style dome insulation

You could glue little depth guides at stragetic spots around the dome and cover with the insulating concrete until they are covered. I would use a stiff wire (like coat hangers) and bend the bottom into a little circle that would form a large enough base to hot-glue to the dome.