Roofing Glossary

Closed (Closed-Cut) Valley

A closed valley — usually a closed-cut valley — runs the shingles from one slope all the way across the valley, then cuts them in a straight line a couple of inches off center. The shingles from the adjoining slope butt into that cut line. The result is a clean, continuous-shingle appearance.

Closed valleys look tidier than open metal valleys, which is why they are popular. But the cut line is a vulnerability: water running down the valley hits the cut edge of every shingle, and any lifting or poor sealing at that line lets water under. They also trap debris against the cut edge more readily than open metal.

Installation quality is everything in a closed valley — the cut must be straight, the underlayment and valley lining beneath must be flawless, and the shingles must be well sealed. A sloppy closed valley is one of the leakiest details on a roof.

Why It Matters

Closed valleys trade a small amount of performance for appearance. On a well-built roof they are fine; they simply demand better workmanship than open valleys to stay watertight.

Questions about your own roof? Request a free estimate or call Nucci Brothers Roofing at (301) 458-1003.