We recently installed a beautiful new roof for our customer in Renton. There was some active leaking on her roof so we took a look to asses the problem and it turned out she had a dead valley on her roof. A dead valley is created when two or more slopes meet, or when a roof slope meets a wall where water can not easily runoff the roof. These areas are very low sloped and sometimes completely flat. This typically results in ponding because the water has nowhere to flow. As water sits it can find weak areas on the roof and penetrate into the attic and eventually create a leak. The best way to treat a dead valley is by applying a PVC membrane to the area where the valley terminates. PVC is a long lasting material that will withstand ponding better and longer than any composition shingle.
The customer has also experienced some leaking around her chimney. We always install straight line Chim-5 counterflashing on brick chimneys along with a new back pan to protect against water pentration. Dead Valleys and Chimneys are two areas of any roof that are most vulnerable. Make sure your new roof includes the best protection to keep you dry for years to come. A new roof should be beautiful and functional.