Cut away the old caulk from around the vent pipe.
How to replace a roof vent pipe.
How to replace the box vent on your roof.
Slide a new roof jack sized to fit your vent pipe over the pipe.
With the pipe in a vertical position trace around the pipe using a pencil.
Position the vent pipe up to the bottom of the roof.
The penetration will be oval to have a round pipe exit vertically through a pitched roof you need an oval hole in the roof.
This old house general contractor tom silva shows how to create a watertight seal around a vent pipe.
Carefully pry up the shingles around the roof jack using a flat pry bar.
Slide the new flashing over the vent pipe and under the shingles above the pipe.
See below for a shopping list and tools subscribe to.
Works for any size pipe.
Video turorial on how to change out a plumbing vent boot.
Pull the old flashing up over the vent pipe and scrape any old caulk and debris off the roof.
Pry up the old jack and remove it by pulling it up over the vent pipe.
Use a pocketknife to scrape rough edges and sharp points from upper end of plastic vent pipe.
Slip a flat bar under the edge of the vent flashing and pop the nails up photo 1.
Remove any roofing nails and slide out the shingles.