The three valley styles
- Closed-cut valleys: shingles from one plane run across the valley, the other plane's shingles are trimmed along a line. The valley is shingled over; you see no metal. The most common style because it's fast and uses no extra material.
- Woven valleys: shingles from both planes interlace across the valley. Mostly a legacy style; the weave can bridge unevenly and trap debris, and we rarely build them.
- Open metal valleys: a wide metal channel (typically a W-profile) is installed in the valley, and shingles from both sides stop short of its center. The water rides the metal. You see a clean metal line.
How they handle water
All three shed ordinary rain fine when new. The differences show up under stress. Closed valleys ask shingles to do a job at the roof's highest-volume channel, and shingles in the valley wear faster than anywhere else: the concentrated flow scrubs granules with every storm.
Metal doesn't have granules to lose. An open valley gives the heaviest water on your roof a smooth, durable, purpose-built channel, and the shingle edges sit out of the main current. Under ice or the occasional valley snow-melt cycle, the smooth channel also gives backing water fewer seams to probe.
How they handle Oregon debris (the deciding factor)
Here's where our recommendation gets local. Valleys under Doug firs and cedars collect needles constantly, and debris dams in valleys are one of the main ways standing water starts. A closed valley's shingle texture grips that debris; an open metal valley's smooth channel sheds much of it on its own and surrenders the rest easily to a cleaning.
Around Damascus, Clackamas, and Happy Valley, where tree cover is the rule rather than the exception, that difference compounds every single year of the roof's life. It's why metal valleys are our default recommendation here, not just an upgrade for special cases.
The honest trade-offs
Cost: an open metal valley adds material and detail work, so it costs more on installation day. Against a couple of decades of better debris shedding, slower valley wear, and easier maintenance, we think the math favors metal comfortably (valley repairs are mid-tier repair money; avoiding them buys back the difference).
Looks: this one's genuinely subjective. Some homeowners love the crisp metal line, some prefer the all-shingle look. Color-matched valley metal splits the difference nicely.
Whichever style your roof has today, the maintenance rule is the same: keep the valleys clear. (The care calendar covers when.)