Recognize open and closed valleys, understand why the selected method matters, and know which installation photos to request.
A valley is the inward junction between two roof slopes. Start with a wide photograph: following that line down the roof makes this detail much easier to understand than an isolated close-up.
Understand the detail
Owens Corning’s July 2026 Duration instructions describe a lined closed-cut valley and also permit woven and metal alternatives. The selected method determines the liner, shingle layout and fastening restrictions. Use the instructions for the actual shingle rather than transferring one product’s valley detail to every roof.
The cut line and protected water channel are separate from the fastener locations. This figure illustrates the closed-cut option for Duration shingles; open-metal and other approved valleys use different details. Source: Owens Corning, Figure 6. View original detail.
At a glance
| Visible style | What you recognize |
|---|---|
| Open valley | A visible drainage channel between the roof slopes. |
| Closed-cut valley | Shingles cover the valley with a defined cut edge. |
| Woven valley | Shingles from opposite slopes interlace. |
| Hidden layer | Ask for photos of the liner before it is covered. |
Three steps for a clearer roof inspection
Identify every valley. Include short valleys above porches and near dormers.
Name the method. Have the estimate specify which detail will be used.
Ask for staged photos. Request the prepared valley, the installation and a finished wide view.
Is an open valley always better?
Ask why the proposed method suits your roof and chosen shingle. Comparing appearance alone leaves out the underlying assembly. Your contractor should be able to point to the applicable product detail.
Explore the connected details
Read the related roofing guide
See the roof shown in this guide
The cover is a completed-roof example from our project library. It is not proof of a particular shingle brand or of concealed installation details.
Sources and further learning
Owens Corning: Duration installation instructions, valley construction
Owens Corning Contractor Academy: technical training topics
Prepared by Barnes N’ Roofs, serving the Austin and San Antonio metro areas from New Braunfels. Technical review: September 22, 2026. Installation must follow the selected product instructions and applicable local requirements.