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I should be more clear. When I say support, I mean the top end. The flue would be mortared to the vent transition I have built on my arch and the front of the dome.
I guess my question is this: Is a lighter weight chase, a stuccoed box basically, enough to support the top end of the chimney flue and the chimney cap? I don't want to have to build a massive brick chimney; I am not confident in adding all that much weight to the arch, so I would have to go outward of that and build quite a large brick enclosure. Plus, the head of the design committee says she doesn't want to create the "mausoleum" look.
I built a masonary flue, surrounded by metal studs and concrete board. The flue projected 1" above the top of the flue. i cut the concrete board close, then used a high temp caulk to fill the gap. I didn't use any insulation as i wanted to make sure i had a good draw. has stood up very well for more than 2 years.
I had the same thought, but my rationale was different. By insulating the flue, it would loose less heat and stay hotter. Mine also draws well -- 5 feet of 8 inch flue tile (6 inch inside). I suspect it simply doesn't matter. The other reason I used for putting insulation between the flue tile and the steel framing was that I wanted to hold the tile snuggly in place, but I did't want to attach anything to it.
Member WFOAMBA Wood Fired Oven Amatueur Masons Builders America
I have also heard that insulating the flue would increase draw by allowing the tile to heat up faster; but I've also read about leaving airspace around the tile to allow for expansion and movement. That's part of the question for me. Insulate, or airspace? How soild?
If you insulate with vermiculite/concrete mix, like Les, that should still allow for some expansion, yet provide stability. Many builders cover the entire dome with this stuff, and it works well. That's my plan. If you look at my pics, I used a steel framed surround with concrete board that I will stick on some stone veneer. The space in between is filled with vermicucrete. I think I went with the Mausoleum look that your wife was hoping to avoid!
The airspace IS insulation, as well as a provision for expansion. I think, in seismically active areas like California, that firestopping (which is a form of refractory insulation) is supposed to substitute for the airspace.
I live in Sacramento, which is a seismically stable area (knock on wood). But does the airspace alone provide sufficient insulation? Would it be better to put in insulation? If so, would loose perlite filling the chimney chase be a good idea?
Mike, that's basically what I'm thinking/hoping, but with a slightly smaller enclosure. Or possibly just a chminey tower with an igloo. I don't know... the conversation about design styles has reached a fever pitch around the house recently, as we're at a crucial turning point.