closed-cut valley

A closed-cut valley is a roofing detail where shingles from the dominant roof slope run across the valley and over the shingles from the subordinate slope, which are cut back and tucked underneath. The shingles from the steeper or longer roof section extend 12 to 16 inches across the valley centerline, fully covering the valley line while concealing the cut edges of the opposing shingles below. This creates a sealed, overlapping joint rather than an exposed valley line.

The technique requires careful positioning during installation. The shingles from the covering side are laid first, running their full length across the valley. Shingles from the other side are then cut back 2 to 3 inches from the valley centerline and inserted underneath the overlying shingles. The exposed top layer provides the weather shield; the recessed shingles are nailed but remain largely hidden. The transition should be staggered so no single course from either slope aligns exactly at the valley.

Closed-cut versus open-cut

An open-cut valley exposes the valley line itself and requires separate valley flashing to be visible and sealed. A closed-cut valley eliminates this exposed gap and relies on the layered shingles and an underlaid metal or ice-and-water shield for weather protection. Closed-cut reduces the number of distinct flashing pieces and can look cleaner aesthetically, but it demands more precision during layout and cutting to avoid gaps where water can penetrate.

Common problems include improper cut depth, leaving too much of the subordinate shingles exposed at the valley line, or cutting too far back and creating pockets where water sits. If the overlying shingles are not seated firmly or lack sufficient nailing, they can lift in wind and expose the joint. The valley also concentrates water flow from both slopes, so any opening is a rapid entry point for leaks into the roof deck and interior.

Closed-cut valleys are standard on residential asphalt shingle roofs where two slopes meet at different angles or elevations. They are less common in commercial standing-seam metal roofs, which use different valley approaches. The term reflects the outcome: the valley is visually and functionally closed by the overlapping shingles, leaving no open seam or gap to weather.