31" Geodesic 2V build in Southern Cal

[hankplank]

Hello all from Southern Cal! I wanted to share my experience so far building a geodesic dome WFO (and hopefully get some tips along the way) as I've learned so much from and been inspired by everyone in the forum, including dmun's prior geodesic build in the 2000s posted here.
Since I had zero masonry skills when I started this I had thought about casting a geodesic dome but finding castable here in SoCal, especially at a reasonable cost, turned me off to that. I found dmun's thread doing a geodesic dome with brick and, since I could get firebrick (Pacific Clay) at about $1.10 a piece here I thought I'd try that route.
Another major reason for doing a geodesic dome for me was being able to build a model of a 2v dome using this 3d printed part, https://www.thingiverse.com/thing:3215, and wood dowels. Using calculations from https://www.ziptiedomes.com/geodesic...calculator.htm, I started making templates for triangles and off I went.
I've posted a photo below of where I'm currently at, which is figuring out the opening. Here's a video as well of a walk around: https://photos.app.goo.gl/a8JJTkPPPL3HXsxh7.
The triangle sides are 9 5/8" or 8 1/2" so I had to cut it from three firebricks and mortar the pieces together. I cut the bricks at angles of about 10.5 degrees for the larger symmetrical triangles and 9 degrees for the smaller asymmetrical ones. The angles and dimensions are such that I calculated about 1/8 inch of space at the outer side for mortar and room for error (and very glad I did).
Everything is currently set dry with no mortar and the first course can stand up on its own without support but obviously the second will need support initially. I'm hoping that if the finished dome will mostly stand on its own without support I can leave a few inside gaps without mortar for expansion tolerance and mortar more on the outside? I also haven't cut the floor bricks to fit the dome yet but plan to.
Considering I've never done anything like this, things have gone as well as I'd hoped. But if anyone asks I'd say yes this is a bit crazy and I'm not sure I'd recommend this route because the cutting, at least for me with a circular saw and diamond blade, is very slow and stressful. I think it'll take me a month to do the dome alone but I only put in an hour or so a day. I do hope it pays off with less mortar needed, a strong dome and of course good food! I currently have an Uuni Pro which is good but limited and I hope to bake much bread.
In case anyone is wondering the floor is sitting on about 5.5" of perlite concrete in ratios of about 6:1. I plan to insulate the dome with 3" of rockwool batt and probably another 2-3" of pcrete before mortaring. I'm also thinking about porcelain tile on cement board for the vent area and landing. Hopefully others find this useful and of course any suggestions/comments welcome.

[david s]

That’s a very interesting build. I do recal dmun’s geodesic oven. Unfortunately it fell to bits after a few years use, I think primarily because it was too thin, only 2” from memory, which is insufficient thickness for a brick dome to have enough strength at the mortar joints. I hope yours is thicker. The general rule for a brick dome is to make it 4” thick.

[hankplank]

Uh oh mine is only 2.5" thick. That is unfortunate about dmun's build and thank you for letting me know! I am a bit far in to do much about that now except keep that in mind regarding the thin mortar joints. Hopefully the dome will be sufficiently tapered and self supporting so as to not fall apart. Perhaps I can reinforce it with a layer of homebrew on the outside?

[david s]

Yes, that might help.

[hankplank]

So I was hesitant to update this thread because I wasn't sure if the concept would work but after firing the oven now for over a year it's holding up well.
In case anyone is thinking of trying a Geodesic dome, I think the challenges are cutting all the triangles, supporting the oven opening and fitting all the pieces together as you mortar them. I had to do a little bit of grinding here and there to get the triangle pieces to fit correctly as I got to the top of the dome. But having a geodesic model to follow was crucial and is sort of like using the IT as a guide in a traditional build. And using instructions for precut brick oven kits as inspiration, I ended up constructing an arch shaped to support the oven opening which, although tricky, I think worked out well. Lastly, this was all very slow going work cutting the bricks to make triangles and the supporting arch.


Probably the main advantage to doing a dome like this is, knowing how all the pieces should fit together, I mostly only needed very thin mortar lines, no more than a quarter inch except for the arch. I only used about half of a 50 lb bag of refractory mortar. The other advantage is if you want a thin, about 2-2.5" thick dome this will get you that. I estimate the dome and oven floor is only about 500 lbs.
Well hopefully this is of use to someone and I'll be hopefully finished with the tiling and stucco sometime soon! Thinking of calling it Spidey cause I think of a Spidey web when I look inside.