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Roofingaka: roof valleyaka: valley flashing

Valley

In Plain English

The V-shaped channel formed where two roof slopes meet — one of the most water-vulnerable areas of any roof.

Definition

The internal angle formed where two sloping roof surfaces meet, creating a channel that concentrates and directs rainwater down the roof. Valleys are among the most leak-prone areas of a roof and require special waterproofing — either open metal flashing or a closed/woven shingle detail. Ice and water shield is typically required in the valley for cold climate applications.

Example

The W-metal valley flashing was installed before shingles and extended 12 inches on each side to handle the concentrated water flow.

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