A roof valley is the internal angle where two roof slopes meet, designed to channel rainwater safely toward gutters and drainage points.

In roofing, a valley is the internal junction formed where two sloping roof surfaces meet. Valleys are critical drainage components, directing rainwater, snowmelt, and debris off the roof and into gutters or downspouts. Because they handle concentrated water flow, valleys are among the most vulnerable areas of a roofing system.

Roof valleys are typically constructed using metal flashing, valley liners, or specialized underlayment systems installed beneath the roofing material. Common valley types include open valleys, where metal flashing remains visible, and closed or woven valleys, where shingles or roofing material cover the valley flashing. The choice of valley type depends on roof design, climate, material, and aesthetic preference.

From a construction and performance standpoint, proper valley installation is essential to prevent leaks, ice dams, and premature roof failure. Building codes and manufacturer guidelines often specify minimum flashing materials, overlaps, and installation methods. In both residential and commercial roofing, well-designed valleys significantly extend roof lifespan and improve overall water management.

Because roof valleys handle more water than almost any other roof area, they often wear out faster than surrounding shingles and may need replacement before the rest of the roof.

• Shake (Roofing)
• Tear-Off (Roofing)
• Underdeck Roofing