For the valley areas of the roof you will be using valley flashing.
Installing flashing on porch roof.
Lay the cut flashing down at the corner.
Install the flashing place the flashing between the joint of the house and the roof.
How to flash a porch addition 1.
Install the underlayment as directed by the manufacturer then set the valley flashing on top of it.
Measure the length of the porch roof joint to determine how much flashing you will need.
How to install porch roof flashing step 1.
Cut an angle with tin snips on one side of the flashing piece from an end.
Prepare the area where you will install the roof flashing.
Nail the flashing securely in place using roofing nails.
Put on a pair of leather palm gloves to avoid injuries from the sharp edges of the metal flashing.
The flashing on the wall should be flush against it and the porch roof portion should be on top of the shingles.
If you already have faulty flashing installed you.