The roof over Kentuck Knob

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SDR
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Post by SDR »

I find this note among the contents of the Berridge matter linked above by Paul R:


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Tom
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Post by Tom »

9.3 x 10-6 (50ft x 12in/ft) (85-30) = 0.307 in

Looks like hard drawn copper of 50ft length will expand a little more than 1/4" during a change in season.

SDR
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Post by SDR »

I wonder if a metal roof today might be constructed as a "rain screen," as is done routinely with exterior wall construction. That is, the outermost surface is intended to take the brunt of the weather but is not itself made water-tight. Might the copper Bermuda roof be laid, with loose folded-metal joints, over a membrane roof ? Or would this invite trapped water, assuming the metal is laid directly on the membrane-covered sheathing, to support the occasional human foot ? If the metal were laid so water could drain beneath it, then the metal would presumably be too fragile to support weight . . .

I don't see how soldering could be done well in one part of the world, and (with the same materials) not in another. Perhaps the metalworkers Laurie encountered didn't have their copper sweat-soldering techniques perfected ?

SDR

Laurie Virr
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Post by Laurie Virr »

Stephen’s speculation with regard to the skill of the local tradesmen may well be correct.

Despite what I have observed at the John and Syd Dobkins house, I share Tom’s reservations with regard to the practice of filling the joints fashioned to allow for expansion with more metal in the form of solder. Solder, by definition, has a lower melting point than the material being connected, almost ensuring it would fail first.

Lead free solders are now available, but to my admittedly imperfect knowledge, were not available in the early to mid-1950’s.

The roof of Kentuck Knob, as depicted in the images published, looks absolutely immaculate. How was it done?

SDR
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Post by SDR »

True. I see one seam, and some drip lines (?) in the photo. What material is it that the Berridge roof is made of ? They permit up to 30' without seams ?

Aren't copper hot-water supply pipes routinely sweat-soldered ? I watched plumber Rich Trethewey doing the job (yet again) on "This Old House" the other day. The flame is applied at one end of a coupling and the solder applied at the other. He says the solder is drawn to the hotter part of the joint, thus filling the seam . . .

Perhaps Laurie will have to tour his part of the country until he spots a properly made Bermuda roof -- and track down the craftsman responsible ? I wonder what research short-cut would make that a less time-consuming task.

Would a very wide overlap, with a fine up-turn or return on the buried end and no solder, allow for expansion and still shed water ? Musn't the clips also reliably allow for some horizontal movement ?

SDR

Laurie Virr
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Post by Laurie Virr »

The cross section thru a typical pan for a Bermuda roof is analogous to a lazy Z, with crushed folds top and bottom. On stepping down the roof, the lower leg of the upper pan overlaps the upper leg of the lower

When connected to an adjacent pan in the same plane, both the horizontal and vertical elements of the joint have to be formed. There is little evidence of the former in the published images, and none of the latter. To my knowledge the roof has always remained weathertight.

Would access to the working drawings and specifications furnish the answer, or was the final result entirely dependent on the skill and experience of the artisan?

Paul Ringstrom
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Post by Paul Ringstrom »

Bermuda Roofs apparently are now called: Horizontal Seam Roofing

Description: Horizontal seam roofs consist of copper pans, whose long dimension runs horizontally across a roof, attached to horizontal wood nailers. At each nailer a step is used to allow adjacent pans to lock effectively. The height and spacing of the steps may be varied or additional steps may be included between locks to achieve different appearances.

The copper pans may be supported by rigid insulation, inserted between nailers, or by wood sheathing applied over the nailers.

from the Copper Development Association:

FLAT SEAM ROOFING RECOMMENDATIONS:

SLOPES GREATER THAN 6:12 – DRY SEAMS WITHOUT SEALANT OR SOLDER.

SLOPES GREATER THAN 3:12 UP TO 6:12 – SEALANT OR BUTYL TAPES CONCEALED IN SEAMS.

FLAT AND SLOPES UP TO 3:12 – FULLY SOLDER SEAMS.

http://www.copper.org/applications/arch ... ofing.html

Some good sectional drawings here:
http://www.copper.org/applications/arch ... ofing.html

therman7g
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Roof

Post by therman7g »


SDR
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Post by SDR »

The Dragon's eyes glimmer, through screen of wood under copper brow, its head and foot of stone . . .

Tom
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Post by Tom »

Great photograph, incredible roof, cool poem.
PaulR: thanks for the links.

SDR
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Post by SDR »

dtc forwards the following article.


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Paul Ringstrom
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Post by Paul Ringstrom »

You could certainly tell that this was an industry publication by the detail provided when they described the installation of the new roof.

If I remember correctly the fully soldered flat panels copper sheets on the shed roofs were also the way the Dobkins House was done.

dtc
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Post by dtc »

Originally Wright designed this Bermuda-style roof to transition to a built up coal tar roof for the flat areas. They made a change when they finally applied the copper that should eliminate future problems in such a critical area.

There is information in this article that many will find interesting.

Dobkins had the same transition, and it was at that critical location that they experienced water penetration early on. When I addressed the entry and carport roofs we needed to tear out all wood for it was completely rotted. Luckily there were 2 steel I-beams, installed originally, supporting the carport cantilever roof.

Wrightgeek
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Post by Wrightgeek »

While I'm not sure that it has the Bermuda-style roof being discussed in this thread, the Unitarian Meeting House in Wisconsin also has a copper roof, which was completely replaced not too many years ago.

dtc
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Post by dtc »

The Unitarian Meeting House does have a Bermuda-style copper roof.
Yes you are correct in that it was replaced not to many years ago.

If I'm not mistaken the Hagan (Kentuck Knob) roof was replaced as well. When Lord Palumbo the second owner had the home restored, a fire broke out in the carport area and much of the ceiling along with the roof was replaced.

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