How to Install Valley Flashing
Protect your home against leaks with one of three ways to shingle a valley. We show you how to do it yourself!
Valleys are notorious for developing leaks. In downpours, torrents from two planes of the roof meet. Often they are dammed by debris. These factors can cause water to go under nearby shingles, resulting in leaks. There are three ways to roof valleys: open metal, closed-cut, and woven. All three work well, but check which is preferred by your local building department. Regardless of the method you choose, do not drive nails within 6 inches or so of the valley center or you will provide an unwanted pathway for water.
A strip of waterproofing shingle underlayment, or WSU, provides extra protection and is an essential component of woven and closed-cut valleys. It is also a good idea for an open metal valley.
Chimney flashing is fairly complicated. If your chimney did not leak before and you can use the old flashing pieces as templates for the new, you should have no problems. However, if you have no templates, you may want to call a professional roofer.