How to Flash a Metal Roof Vent

A variety of metal vent pipes extend through a home's roof, including sewer vent pipes and exhaust pipes for fans and dryers. Since they require a hole in the roof material, they are subject to leaks. To prevent this, a flat metal material, called flashing, resides around the pipe's perimeter and directs water away from it. Although attaching flashing is not complex, you must insert it under the shingles properly.

Ladder
Vent flange with flashing
Shingle ripper
Chalk
Utility knife with flashing
Galvanized roofing nails
Hammer
Roof caulk

Instructions

- 1
  Use a ladder to climb onto the roof and walk to the pipe's location.
- 2
  Insert a vent flange with flashing over the vent pipe and take note of how many shingles it covers above the pipe. Lift it off and set it aside.
- 3
  Lift up the shingles previously identified and insert a shingle ripper under them. Hook the nails with the shingle ripper and pull down hard to dislodge them. Remove the nails from all the necessary shingles, but do not pull the shingles out of position.
- 4
  Lift the shingles up and put the flange back in place. Trace around the upper round portion with a piece of chalk to draw a line on the shingle where you must cut it. Cut along the chalk line with a utility knife until the upper shingles lay flat against the flange.
- 5
  Hammer galvanized roofing nails in each corner of the flange. Insert additional nails in the top lip of all the upper shingles, spacing them every 3 to 4 inches.
- 6
  Apply 1/4-inch diameter of roof caulk on top of the nailheads to waterproof them.

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