Installers need to flash round shapes, such as plumbing vents or pipe supports for rooftop equipment, through the roof using ethylene propylene diene monomer (EPDM) rubber pipe flashings. The cone-shaped rubber is field-cut to size and stretched to fit the pipe. Technicians should use a stainless steel draw band at the top of the flashing to ensure it never inverts itself.
Installers also must anchor the pipe flashing only to the roof panel, not to the building structure or deck. To do the latter would inadvertently pin the roof panel, compromising its freedom in response to thermal movement. These flashings should be centrally located to ensure free drainage. In any event, technicians should avoid interrupting a seam.
This flashing assembly is sealed to the roof with butyl copolymer tape sealants, is easier to replace and should offer 20 years or more of service life.
Rooftop mountings and penetrations are a challenge for any roof type or material. Following these guidelines will ensure trouble-free and enduring performance for low-slope metal roof systems.
Rob Haddock is director of the Metal Roof Advisory Group Ltd. in Colorado Springs, Colo. He is an internationally recognized expert on numerous technical issues relating to metal roofing.
Standing-Seam Metal Roofs Provide Anchor for Rooftop Equipment
Standing-Seam Systems: Follow Rules for Handling Penetrations
Metal Roofs: Use EPDM Rubber Pipe Flashings Around Vents, Pipe Supports
