Plumbing Vent Flashing

Plumbing vent flashing, also known as a pipe boot, pipe jack or vent collar, seals the hole where a drain-waste-vent pipe or similar round penetration passes through the roof. It is usually a flat flange with a raised sleeve or rubber collar that fits tightly around the pipe. Materials include lead, aluminium, galvanized steel with an EPDM collar, and all-plastic or rubber designs.

Installation on a shingle roof

Canadian guidance describes:

1. Flash every pipe and projection through the roof with a flange extending at least 150 mm (6 in) onto the roof and nailed securely.
2. Weave the flange into the shingles: the lower part lies over the course below, and the upper part is covered by the course above.
3. Align the bottom edge of the first shingle covering the flange with the bottom of the pipe so water cannot run under the flashing.
4. Where a shingle cutout or sealant line falls level with the flange edge, add a piece of shingle or cement beneath to block a leak path.
5. Cut the shingles cleanly around the sleeve, leaving about 12.7 mm (1/2 in) of clearance so granules and debris wash away.
6. Use only the nails needed and seal any exposed heads with compatible sealant.

Lead and soft-metal boots

Lead boots are dressed by hand to the roof profile, and their tops are turned down into the pipe to form a cap. They suit uneven coverings such as tile and slate.

Service life and inspection

Rubber collars on combination boots weather and crack with sun exposure and often fail before the main roof covering. Roof inspection checklists list deteriorating caulking and separated flanges at penetrations as common problem areas. On membrane roofs, pipes are sealed with prefabricated or field-formed membrane boots and clamps rather than nailed flanges.