Pipe Boot (Vent Pipe Flashing)

A pipe boot, also called a vent boot, pipe flashing or (in the UK) a pipe collar or lead slate, seals the opening around a round penetration such as a plumbing vent stack, flue or conduit. It consists of a flat flange that integrates with the roof covering and a raised collar or cone that wraps the pipe.

Types

• Rubber or EPDM boot on a metal or plastic flange: the most common type on North American asphalt roofs; the rubber gasket grips the pipe.
• All-metal (lead, copper or aluminium) flashings: a lead flange with a lead sleeve dressed over the top of the pipe, traditional in Britain and on long-life roofs.
• Adjustable or split boots: used for retrofits where the pipe cannot be removed, or on metal roofs where the flange must follow ribs.
• Storm collars and roof jacks: used with metal flues, which must also keep code clearances to combustibles.

Installation principle

The flange is shingled into the roof: the lower part of the flange sits on top of the course below, while the courses above and at the sides cover the upper part. Water running down the slope is therefore carried over the flange. Exposed nail heads are sealed if the manufacturer requires.

Common failures

The rubber collars of many boots crack with age and UV exposure, typically well before the surrounding roof wears out, and are a common source of leaks on older roofs. Inspection and replacement of cracked collars is routine maintenance. Other problems include boots sized for the wrong pipe diameter, flanges installed on top of the upslope shingles, and squirrel or bird damage to soft lead sleeves.

Metal roofs

On profiled metal roofs, pipe flashings are usually flexible silicone or EPDM boots with a pliable base sealed and screwed to the panel, placed to avoid blocking water flow between ribs.