Penetrations, curbs, skylights and equipment · Lesson 2 of 4

Penetrations, curbs, skylights and equipment: materials, standards and design constraints

Which metals and thicknesses the published details call for, how the 8 inch, 4 inch and 18 inch figures differ by source, and how to keep unlike metals apart.

You will be able to: Name the metal minimums published for penetration flashings, tell which document each height or lap comes from, and explain why the governing document, not a remembered number, sets the dimension on a job.

7 min · 8 slides · 5 questions

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Slide 1 of 8

Copper weights in the CDA details

The Copper Development Association says the minimum weight of copper sheet used in flashing roof penetrations is 16 oz.

Its skylight-head detail forms 20 oz copper, at minimum, into a water diverter.

AFS’s fabrication limits list copper in 16 oz, 20 oz, 24 oz, 32 oz.

Sources

Copper in Architecture Design Handbook - 9.9 Roof Penetrations - Copper Development Association
AFS fabrication limits - materials, thicknesses, bend rules and sizes the shop can make - Architectural Flashing Supply

Glossary

Governing document: The document that sets a dimension or material on a particular job, such as the project specification, the owner’s standard, the roof or skylight manufacturer’s instructions or the locally adopted code.
Water diverter: Formed metal on the upslope side of a curb on a metal roof that directs water around the penetration, as McElroy Metal describes it for curbs.
Draw band: The band the Copper Development Association long-pipe detail uses to attach the cap flashing to the pipe.
Mastic: The compound in which NRCA says primed pocket metal is set on asphalt and coal-tar systems before the flanges are flashed.