I dreamt up this idea that I’d like a sphere vaulted ceiling in my bathroom. So I’d build an 8′ flat ceiling and then have a vault in the middle. The opening would be about 60″ in diameter and raise up 2′ at the peak. The radius of the sphere would be a little over 30″ so I wouldn’t end up with an exact half sphere in the ceiling. The overall room is about 9×11.
How are these things typically built and finished out? I can see I’ll have to frame a 60″ square opening in the ceiling, maybe even an octagon. No problem with that. But what about the final product? I’d *really* like some kind of funky glass that I could backlight, but I doubt I’ll be able to find anything that big. I’d rather not build it out of segments, I’d like to come up with something that is perfectly spherical and no joints. But maybe that’s a just a silly requirement. Come to think of it, copper might look kind of cool up there.
Maybe I could trowel it in using a somekind of homemade wooden float shaped to the curve I need?
Just looking for any thoughts on something I might be able to build or purchase.
MERC.
Replies
In the photo folder there was a recent thread where some one used an old c-band satelite dish.
Yes, I remember seeing that. I wonder what sphere radius those things are. They seem pretty large, like probably 6 or 8' radius.
Expanded metal lathe and plaster - just like an upside-down swimmin' pool.
"Logic, like whiskey, loses it's beneficial effect when taken in too large quantities." Lord Dunsany
Build a hefty center pin and make a screed board to the shape you want. use plaster and scrape till you are done . Don't let it set without scraping to the final size . (holes are ok bumps are not. ) Keep adding plaster till no more holes exist. That is what the guy told me that used to do moldings and medalions. Also he said that he had used durabond 45 for some of his last projects. Cover the floor and wear gloves he said.
Is the backing just metal lathe? Or something more traditional like blueboard (cut into strips to install?) or bending drywall (again, cut into strips)?
MERC.
Unless you have Brisketbean on your payroll.I think that I would use the metal lathe . Much easier to conform to the compound bends that you will encounter .
The satalite dish is a good idea . It is a parbolic curve , close to what you wanted shape wise.
You can buy the domes prefabricated from various companies.
Here's one -- I've no doubt there are plenty of others.
IanDG
Wow, that's pretty sweet. No prices though...that can't be good news.
MERC.
I can give you some advice that I'm sure you can apply to your problem. I think the best way to frame this is with ply wood. I was part of building a dome in Naples Fl. a couple of years ago, well more than a couple 1996. It was much larger than the one you described, over 12' radius. Here's what we did. I wasn't the lead, by the way.
On the floor describe the circle that will be the circumference of your dome at ceiling level, 30'' radius right. Then snap a line down the center. and layout from the center each way on (I would use) 8'' center. This shows your dome in plan view.
You said the rise of the arc in the center will be two feet. Make sure you leave enough room so that you can install your arced frames in one piece, meaning drop a couple of inches if this distance takes you right up under the existing ceiling joists.
Now you want to create a section view of your dome at the center line. There are different ways to do this but the way I was taught, (I think I learned it in the pages of Fine Homebuilding) is to snap a line on the floor, tic off the total run, 60'' 's. Then create a perpendicular bisector, a square line from the center of the line segment. Measure up the bisector the same number of inches that you want for your total rise We'll say 24''. Now connect this point to either point on the original line and make a perpencular bisector to this new line segment. The point where these two perpendicular bisectors intersect is the center of the circle. Describing this arc will give you a section of the center of the dome. Now layout, on 8'' centers, this arc exactly the same as the other. Make sure your layout is equidistant from center on both sides. This will allow your to make two of each off the arc frames, one for each side and make less work.
Using the dome in plan view you can measure each of the runs. They get smaller as they get farther from center. Using the section view laid out will give you the rises in the same way. Having the rise and runs and the method I described above for finding a circles center you can use these measurements to describe new section views. The section views can be transferred to ply wood cut out and installed as rafters. Any perpendicular blocking can be described in the same way. I hope this isn't to confusing. But I'll be glad to answer further questions.
Not to be picky but for a true half sphere the radius (30") would be equal to the height in the center (30").
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Yes I agree, but I don't want the edge (where it meets the flat ceiling) to be vertical. So I'm going to use the top 24" of a 30.75" radius sphere, which should give me a 60" opening with a 24" height.
BTW, I found this stuff last night: http://www.artfiberglass.com/46.html
MERC.