A Copper Alliance Member
Domes, Spires and Vaults:
Circular Dome with Diagonal Flat Seam System
Description: The details show a circular dome capped with a ventilated copper cap. The cap is designed to allow for air to flow out of the dome, while preventing any water, from entering. The cap must also be designed to withstand local wind loads.
On the low-pitch areas near the top of the dome, the seams must be soldered to ensure water- tightness. As the pitch of the dome increases, sealant may be used in the seams. Near the base of the dome, where the pitch exceeds 6" per foot, no solder or sealant is required. See Roofing Systems - Special Design and Installation Considerations Section 1.2, for more information.
At the base, the copper panels are usually 8 to 12 inches square. The practical panel sizes that can be efficiently fabricated and installed are 4 to 6 inches minimum and 16 to 18 inches square, maximum. There are a constant number of panels around the perimeter of the dome. They diminish in size as they get closer to the top.
Diagonal flat lock panels are particularly well- suited for covering irregular curved surfaces.
A cornice is shown at the base of the dome. A built-in copper gutter can be used, to control run-off as shown in Detail E. A copper cap, like the one shown in Detail A of Standing Seam System, can be used at the top as an alternative.
The minimum recommended weight for the panels is 16 ounce copper.
Substrate: Continuous nailable substrate.
Fastening Method: Cleats
A. Elevation This detail shows the continuous panel seam that runs from cornice to cap, and the spiral effect of the diagonal copper panels on a circular dome.
B. Plan The diminishing size of the copper panels is clearly visible. When designing this type of dome, consideration should be given to the size of the panels, as they can get very small. If their size becomes too small to construct, panel sizes can be modified by deleting every other seam and doubling the resulting panel size, as shown in the left half of the detail.
C. Partial Elevation This elevation shows a typical panel layout on the dome. First, determine the number of full panels required to circle the dome based upon its size and the desired appearance of the cladding. Determine the diagonal (AB) of the first course by subdividing the dome perimeter into equal divisions. Form the half panel starter course with the required folded seams and attach to dome with cleats and fasteners.
The length of the diagonal of the next course can now be measured directly from the upper points of the previous course.
Patterns
Pattern for Course 1 The first course is a half panel as shown. The flange along the bottom is folded under to lock into the base flashing below, as shown in Detail E.
Pattern for Course 6 The dimension DF is determined after the panels for course 5 are laid out.
E. Section at Cap – Venting
The cap shown is made of 20 oz. copper. Its design allows for air to flow out from the top of the dome. If venting is not desired, a non-venting cap may be used, see Detail E on Plate 4.7.4. The cap is support by 24 oz. copper straps secured to the dome, and spaced at 12" on center, or closer as needed to meet structural requirements. The upper edge of the diagonal flat seam roofing panels are cleated to the dome. Copper flashing, formed to follow the opening in the dome, is locked into the upper edge of the roofing. The inside edge of this flashing is formed into a bread-pan and fastened with cleats to the deck. Special equipment may be required to stretch the copper into the proper shape.
F. Section at Cornice This detail is used to transition from the dome to a cornice condition. The cornice cover is turned up, hooked under the first course of the dome panels, and fastened with cleats.
G. Section at Gutter This detail can be used to transition from the dome to a built-in gutter. The gutter liner is fastened with cleats at 12" o.c. and is overlapped 4" by the dome panels. A lock strip is soldered to the gutter liner and engages the first course of the dome panels.
For Additional Information:
- Roofing Systems – Introduction, for general information on roofing system requirements.
- Flashing and Copings, under the appropriate sections for flashing details.
- Gutters and Downspouts, for gutter flashing details.
- Wall Cladding Systems – Diagonal Flat Lock Panels, for variations of diagonal flat lock panels.
Design Handbook
Available in 2 formats:
Download AutoCAD Files
AutoCAD Detail Files
[ZIP - 4.5MB] is a complete set of CAD files for the designs shown in Architectural Details.
The AutoCAD files for individual details can be downloaded from individual topic pages by clicking the CAD File button next to an individual detail.
Order Design Handbook
(publication #A4050).
