In this video, This Old House general contractor Tom Silva shows how to create a watertight seal around a vent pipe.
Steps for Fixing a Leaking Rooftop Vent Pipe:
- Use a pocketknife to scrape rough edges and sharp points from upper end of plastic vent pipe.
- Cut away the old caulk from around the vent pipe. Use the knife blade to scrape the pipe clean and smooth.
- Apply a thick bead of lap-seal caulk around the seam between the vent pipe and old rubber gasket. Then run a second bead of caulk just below the first bead.
- Slide the replacement rubber gasket over the pipe and press it down tight to the flange.