How to Flash Around Drain Vents on a Metal Roof

One area on your roof that is susceptible to leaking is around the drain vents. The drain vent, or soil pipe, allows air into the plumbing system for drainage and to flush toilets. Most often soil pipes have a roof jack as a flashing. A roof jack is a collar that fits around an exposed soil pipe and has a rectangular piece of sheet metal at the bottom for flashing. Unlike the case with an asphalt roof, flashing around drain vents on a metal roof does not require removing any of the roof.

Flat pry bar
Utility knife
Drain pipe flashing (roof jack)
Roofing nails
Hammer
Roofing tar
Putty knife
Ball peen hammer

Instructions

- 1
  Cut the tar on the outside perimeter of the flashing with a utility knife. Pry the flashing off of the roof with a flat pry bar. Once the flashing is disconnected from the roof, grab the collar around the vent pipe and lift the collar and flashing away from the pipe.
- 2
  Slide the new drainpipe flashing over the vent pipe until the flat rectangular flashing is flush against the roof. Drive roofing nails through the flashing at each corner and into the roof with a hammer. Drive two more roofing nails into each side of the flashing between the corner nails.
- 3
  Apply roofing tar to the exposed perimeter of the vent pipe flashing where it meets the roof with a putty knife.
- 4
  Bend the top of the vent pipe flashing collar over the top of the pipe with a ball peen hammer.

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