No matter which valley method you use for extra protection apply wsu at a valley.
Using paper in a roof valley.
Roll out and smooth the wsu and drive a few nails on one side to hold it temporarily.
Fold the top over the roof ridge and cut the bottom along the drip edge metal.
You can center it and align it smoothly with the roof contours as you go down.
Closed cut valleys also called closed valleys are installed.
Felt paper should extend at least 10 inches up each side of the roof valley so use a strip between 20 and 24 inches wide.
Lay the felt paper from the top of the roof valley to the eaves at the roof edge.
Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing.
The three methods to shingle a roof valley.
Fold over the other side and peel off the paper backing.
Use a broad strip of felt paper.
With a clean valley you can lay down some peel and stick roofing membrane.
First clean the debris out of the valley including sawdust nails and whatever else is in there.
Snap chalklines on both sides for guides.
Start at the top.