geodesic dome enclosure

[dougrappe]

Lots to think about,

Mark, thanks for the ventilation details, this is what got me started on this whole thing. I figured some moisture inside is inevitable so you have to give it a way to get out. I wanted a dome shaped enclosure but couldn't figure out how to make a water tight one, with ventilation, considered stucco but thought it would really require a free standing internal structure and vapor barrier and flashing, which led me to consider sheet metal. The geodesic structure just lends itself nicely to the oven dome and arch transition.

Cynon, I had considered a standing seam "observatory" style dome, which might be easier to ventilate and I agree seems more likely to stay water tight, just don't think I have the technology on hand to build one. Much of the appeal of the geodesic structure is that I am confident I can do most of the work myself, so I'm not ready to give up on that one yet. Hadn't considered a hammered dome, probably need to rule that out just based on my total lack of experience in that area (I think I'd want to practice on something a little smaller than a 56" diameter dome first) A continuous copper surface sure would look nice though.

I appreciate you sharing your thoughts,

Doug

[cynon767]

I think that if you have the tools and the ability to bend the sheet metal into geodesic forms, you probably have what you need to do a standing seam dome. The sheets are only curved on the vertical axis; on the horizontal, they are still totally flat. That means that you could bend them over a simple radius form and join the seams just as you would otherwise. It would take a little more planning to get the right size and shape panels before bending, but to me that would be worth it.

Whatever you end up doing, good luck. This has the makings of a very interesting and unique enclosure, and I'm eager to see it come to fruition.

-jamie

[MK1]

Doug, I haven't found it mentioned much, so I might be solving a problem that doesn't exist, but I plan on using some .015 stainless I have laying around to make an observatory style dbl lock standing seam vapor barrier on the outside of the firebrick. My insulation layer will be completely sealed off from any vapor travel, inside or out. I can do it fairly easy so I figure it can't hurt.

Mark

[dougrappe]

Jamie, I'll have to play around with that shape, can't quite picture how to make the seams, I didn't want to rely on just lapping them, I'm planning to talk to a sheet metal fabricator to see how I might get part of the work done, maybe the cutting or maybe get a kit of parts made up.

Mark, Interesting idea, I'm surprised that there isn't more discussion on the subject of weather proofing and moisture issues. Make sure to post some pictures of your sheet metal work,

Thanks all,

Doug

[cynon767]

here's a dome that has the basic shape I was talking about.

this page has a few nice examples of cupolas built along the same idea; a bit more ornate than i was thinking of, but similar construction.

As far as the seams go, I think that standing seams, folded over themselves and soldered, would be fairly watertight, especially since there aren't any places where they run horizontally and collect water.

[MK1]

Doug, I think I would fold about 3/4" of metal inward around the perimeter of each hexagon and pentagon, clip with vise grips or pop rivet the entire dome together and then solder away. When it's finished set it upside down and partially fill with water. Touch it up a bit, clean and install. When you're soldering, you don't really have to lock the seams. Don't spare the solder.
Moisture issues and ventilation are not well understood by architects and builders or even the trades in general. It's something I've consulted on many times at the point where lawyers were involved. Remediation was expensive. Codes are so tight now that buildings under construction have been condemned, demolished and re-built because of black mold and moisture issues.
I've included a sketch from the late 1800's

Mark

[dougrappe]

Hey guys, thanks for the photos and drawings.

Mark, regarding moisture and ventilation, I just came across the thread where you guys were discussing foil over or under the insulation and such...so I guess the jury is still out on that one. I'm trying to be kind of realistic and maybe simple minded on this topic. I feel like some way or another moisture is going to get in, so better to give it a way to get out too. So I'm going to shoot for the most weather tight lid I can get and find a way to ventilate it too.

Thanks again,

Doug

[MK1]

Doug, I agree that ventilating the outside enclosure is the most cost effective and easiest. I think this is where the gabled house has an advantage over the igloo in that the vermiculite is exposed to some airflow. As you read the foil thread this is old ground. I'm doing the stainless vapor barrier as I have the materials free and I live in a very humid climate.

Mark