The Roofing Experts in the Seattle & Eastside Areas
PVC Dead Valley on a Roof

PVC Dead Valley on a Roof

In some cases on roof lines, there are areas where water can find its way to a flat section and pond. Many times Pro Roofing can build a chimney cricket, but there are occasions where a cricket is either extremely difficult to build or impossible. These circumstances requite a bit of ingenuity. Most of the time PVC membrane is laid down as a water heavy barrier.

What is a Dead Valley on a Roof?

A dead valley a point on a roof where two slopes meet in such a way that makes it difficult for water to run off. Water flows into the flat area, but does not flow out. This is called a "dead valley" because the Dead Sea also has this phenomenon.

Examples of dead valleys include:
  • Sections of the roof where two slopes meet and water cannot drain off of the roof

  • Sections of the roof where water flows slowly and pools for extended periods of time before eventually running off

  • Sections of the roof where the pitch is so shallow that the roof is almost flat & is prone to collecting water

How to Fix a Dead Valley

Under the PVC dead valley, Pro Roofing will install leak barrier with a felt or separator sheet under it. The PVC dead valley will need to be installed up under the siding. In some cases, Pro Roofing will need to replace part or all of the siding. Other times the membrane will be tied into the brick. In those instances, flashing will need to be cut into the brick.

When finished, the dead valley will be able to have standing water in it and it will not leak. It’s obviously better to NOT have standing water on a roof, but sometimes it is unavoidable and those cases are where dead valleys are used. At times roofing companies have to integrate a flat area into a slopped composition roof. PVC Membrane or TPO can also be used in this case.

For more information, please check out our video below!


Dealing with a dead valley on your roof? Call Pro Roofing NW today at (425) 598-0998 or contact us online to learn more about how we can help you avoid leaks!


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