How to Install Plumbing Vent Flashing

Roof vent pipes are an important and often overlooked component of modern homes. The pipes are separate from the actual roof. Because of this separation, a seam naturally exists between the outside of the pipes and the roof. If not sealed, water will leak through this seam. To guard against this, the seam is covered with a flashing piece specifically designed to accommodate the vents. When installing new roofing material, it is important to install vent flashing rather than attempt to seal the gap with roofing cement.

Preformed flashing vent flange
Pencil
Plastic-based asphalt roofing cement
Roofing nails
Hammer
Utility knife

Instructions

- 1
  Install the roofing shingles only until the shingles reach the bottom of the vent.
- 2
  Lower a preformed flashing vent flange over the vent, and position the flange on the roof.
- 3
  Mark the entire length of the top of the vent flange on the roof's underlayment with a pencil, then lift the flange off of the vent.
- 4
  Apply a coat of plastic-based asphalt roofing cement to the underside of the vent flange and across the pencil mark made in Step 3.
- 5
  Lower the vent flange over the vent, and press the flange into the roof to seat the roofing cement.
- 6
  Drive roofing nails around all four sides of the vent flange with a hammer for added security. Installing roofing nails is optional but can help guard against leaks.
- 7
  Cut the roofing shingles to match the curve of the flashing with a utility knife, and continue installing the shingles up the roof.

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