In simplest terms a new vent pipe boot flashing is slid over the top of the existing one and the top edge of the pan is lapped beneath the overlying shingle course.
How to replace vent flashing on roof.
Slip a flat bar under the edge of the vent flashing and pop the nails up photo 1.
To replace flashing around the vent pipe first remove the shingles covering the flange at the back and sides.
1 remove nails holding down shingles above the pip.
Pull or cut off any nails.
Replace the shingles and cover the nail heads with roofing cement.
Hammer the nails into the top and sides of the flashing.
Bend it back so that it.
How to install step flashing with a wall corner.
To make the installation easier you can turn the flashing as you lower it in place.
Ensure it sits flat and extends at least 8 inches above the shingles.
The flashing should be installed under the top and side shingles but it should be laid above the shingles that are below the vent pipe.
Position a new vent pipe flashing over the vent push it down into place and nail where shingles will cover it.
If there is a split in the shingle along the edge of the flashing be sure to caulk the edge of the flashing.
Pry and lift off the flashing.
Pull the old flashing up over the vent pipe and scrape any old caulk and debris off the roof.
Slide the new flashing over the vent pipe and under the shingles above the pipe.
Bend the corner flashing tightly around the corner.
Cut your shingles precisely to leave at least half an inch around the base.
Nail it in.
Leave the bottom of flashing exposed so only the sides and top are covered by shingles.