I want to design a copper-roofed cap with frame for a large chimney. If you are a metals guy, please offer advice.
What I have dreamed up so far is shown on the attached pic. A steel frame of posts, top under-surround, and cross lineals is bolted to the poured concrete cap. Poking through the cap, and not shown, is a doublewall SS chimney coming from a HeatNGlo fireplace below, and the furnace vent and intake pipes, both 3″ PVC. The fireplace flue has one of those round pillbox termination caps, sitting a little above the poured cap.
The roof with frame sits up above all the flue and vent stuff.
My steel guy can galvanize and paint all the angle, and can breakform all the galvanized sheet I want, up to 16 gage thickness, for doing additional framing and fastening pieces for the copper pans to be fastened to.
But what should that additional stuff be, for the pans to fasten to?
Edited 7/6/2006 6:01 pm ET by Gene_Davis
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BTW, here is where I got the idea. This Frank Lloyd Wright commission, the Heurtley house, built in 1902 on Forest Avenue in Oak Park, Illinois, has a cap just like this on its chimney.
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I'll defer to Grant , so this a bump.
Spheramid Enterprises Architectural Woodworks
There is no cure for stupid. R. White.
You are going to ned to deal with galvanic reation between the steel and the copper
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". . . deal with galvanic reation between the steel and the copper"
You're preaching to the choir, Pif. I was thinking that primer and paint on the galvanized steel would be a start, then taped on strips of Grace's Vycor to isolate the two even more.
I see steel studs as supports and SS screws for the pan tabs, but I ain't the guru, just the grunt.
Spheramid Enterprises Architectural Woodworks
There is no cure for stupid. R. White.
Build your frame out of copper bar. Make a temporary plywood form to build the standing seam roof on. Lift it off and fasten it to the frame with brass bolts.
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But Grant, this thing, out to its overhangs, is about 3 feet wide by 15 feet long.
I am not saying it is heavy, but it sure is cumbersome.
We want the legs to look as if they have some bulk, thus the 3x3 angle size. What size copper bar would you suggest?
Additionally, we are in deep snow country, and are designing for a 66 psf snow load. A couple of wet and nasty winter storms could burden this cap to the tune of about 200 pounds per lineal foot. Over the 15 feet of length, that amounts to 3,000 pounds.
I wish I could just hire a good copper specialist to do this, but up here in this thinly populated and poor region, there are none around. We've one steel fab shop and one tin shop, period. That's why I need to get this deeply into the design and spell it out for a small fab shop.
>>>>>>>>>>>>>>>>I am not saying it is heavy, but it sure is cumbersome.It ought to be well within the range of what two people can pack fully assembled, but I was thinking frame/roof sections to make installation easier.>>>>>>>>>>>>>We want the legs to look as if they have some bulk, thus the 3x3 angle size. What size copper bar would you suggest?I can easily get 1/8x1" which would be adequate for support. Wrap them with a 3x3 sq copper tube for the bulky look and to add some extra strength. >>>>>>>>>>>>>>>Additionally, we are in deep snow country, and are designing for a 66 psf snow load. A couple of wet and nasty winter storms could burden this cap to the tune of about 200 pounds per lineal foot. Over the 15 feet of length, that amounts to 3,000 pounds.Shouldn't be a problem, but the furnace exhaust will help melt the snow off and it will have a tendency to slide off anyway.Using a steel frame under the copper roof is inviting failure. There'll be lots of condensation on the underside. Any sort of gasket (vycor) could deteriorate quickly due to the fireplace exhaust. Have you considered screening the sides? You've designed a good bird house there.I'd have to do some sketching to figure out the framework and I don't have time now. I'll think on it over the weekend and see what I can come up with.
Andrew Douglas: What have you been up to? Jim White: Killin' time... It just won't die.
http://grantlogan.net/
Given the way prices have gone, why copper? Could you go with stainless, or zinc coated stainless? That would get you out of electrochemical trouble with your galvanized steel frame.
-- J.S.