Do not drive nails into the flashing.
How to replace roof valley flashing.
To replace flashing around the vent pipe first remove the shingles covering the flange at the back and sides.
Pry and lift off the flashing.
Lap successive sheets of metal flashing a minimum of 12 inches and seal laps.
Place the new piece of sheet metal valley flashing in the valley with the raised center aligned with the center of.
Install an underlayment centered in the roof valley.
Caulk any openings left and made by the flashing process with a suitable sealant then dust the flashing once it is dry and paint over with granule paint available at hardware stores of your desire.
Then install a non corrosive metal valley flashing of 24 minimum width.
Cut each side of the flashing at the lower end to conform with the corresponding edges of the roof using sheet metal.
Cut the bottom edge and fold it down over the drip edge.
Pull or cut off any nails.
Apply an approximately 3 inch.
Position a new vent pipe flashing over the vent push it down into place and nail where shingles will cover it.
To splice the pieces add roofing cement to the lower piece and install the upper piece with at least a six inch.
How to do it.
Now ask a family member to stand inside the house under the roof valley and then standing on the roof pour a bucket of water onto your handiwork.
Make sure to cover the gap at the bottom of the raised ridge.
With underlayment and flashing installed apply shingles up to one side of the flashing.
Start at the lower end of the valley.
Fold the top of the flashing over the ridge.