Roof valleys are the channels where two roof slopes meet. They carry more water than any other part of the roof — typically 3–5x the volume of an equivalent area of plain roof — because two slopes worth of rainfall and snowmelt all funnel through the valley.
That makes valleys the first part of any roof to leak.
Why Valleys Fail First in Ohio
Three reasons:
**1. Concentrated water flow.** A 1,200 sq ft of roof slope feeding into a 30-inch-wide valley channel translates to roughly 4 gallons of water per inch of rainfall passing through that valley. Multiply by Ohio's 38 inches of annual rainfall and you have ~150 gallons per linear foot of valley per year.
**2. Snow and ice accumulation.** During Northeast Ohio winters, valleys collect snow that doesn't slide off as easily as flat slopes. The mass of accumulated snow slowly meltwater-tests every joint and seam in the valley.
**3. Debris.** Leaves, pine needles, and granules from the surrounding shingles all collect in valleys. Debris traps moisture against the roof surface, accelerating wear.
Three Types of Valley Construction
**Open valley (metal-lined).** A wide channel of metal — usually 24-gauge galvanized steel or aluminum — runs the length of the valley. Shingles cut back from the metal on both sides, leaving the metal exposed in a 5–8 inch wide stripe. **Best performer in Ohio's climate.** Sheds debris, sheds snow, and the metal handles the concentrated water flow without breakdown.
**Closed-cut valley.** Shingles from one slope run completely across the valley; shingles from the other slope are cut to a sharp line about 2 inches off the centerline. **Most common modern installation.** Looks clean from the ground. Performs well in moderate climates but vulnerable in heavy-snow areas because debris collects against the cut edge.
**Woven valley.** Shingles from both slopes interweave across the valley with no cuts. **Rare on modern installs.** Looks rustic but performs worst in heavy-snow climates because the woven layers trap moisture.
Where Valleys Actually Leak
The leak is rarely from rainwater overwhelming the valley — that almost never happens on a properly sized valley. The leak is almost always one of these:
**1. Missing or insufficient ice and water shield.** The waterproof membrane that should run under the entire valley before the metal or shingles are installed. On older roofs (15+ years) ice and water shield was often skipped or installed only at the very bottom of the valley. Without it, water that sneaks under the metal or shingles runs directly onto the deck.
**2. Failed metal flashing in open valleys.** Galvanized steel valley flashing rusts where it meets the shingles. The rust eats through and water enters through the failure points. We commonly see this at year 18–25.
**3. Lifted or torn shingles in closed-cut valleys.** Wind and ice movement lift the cut edge over time. Once the cut edge is lifted, water runs under the shingle and onto the underlayment.
**4. Debris accumulation breaching the underlayment.** Leaves and granules build up in the valley, freeze in winter, expand, and slowly damage the underlayment beneath them.
**5. Improper installation at the eave.** The valley should terminate over the gutter, not before it. Valleys that end short of the gutter dump water onto the fascia and behind the gutter — sometimes for years before anyone notices.
How to Tell If Your Valley Is Failing
From the ground:
- Visible rust streaks running down the valley
- Granule pile at the bottom of the valley (in the gutter)
- Discoloration or staining of the shingles adjacent to the valley
- Active water stains on the ceiling of rooms below the valley
- Sagging or visible deformation along the valley line
From the attic (best test):
- Water staining on the underside of the roof deck along the valley line
- Daylight visible through the valley
- Active dripping during heavy rain
When to Repair vs. Replace
**Spot repair makes sense if** the rest of the roof is under 15 years old, the failure is localized to one section of one valley, and the surrounding shingles are still in good condition. Cost: $400–$1,500 depending on accessibility.
**Full valley replacement makes sense if** the roof is 15+ years old, multiple valleys are failing, ice and water shield is missing under the existing valley, or you're already considering replacement.
**Full roof replacement is the right call when** valley failure is part of a broader pattern of end-of-life issues across the roof.
What Proper Valley Construction Looks Like
When we replace a roof or rebuild a valley, every valley gets:
1. Ice and water shield running the full length, extending at least 24 inches each side of the centerline
2. For open valleys: 24-gauge galvanized steel or aluminum flashing, locked into the underlying ice shield
3. For closed-cut valleys: full underlayment, no exposed nails in the valley channel, clean cut line
4. Termination directly over the gutter with proper drip edge alignment
5. Sealant at the upper end where the valley meets the ridge
Cricket Crickets — Sometimes Confused With Valleys
A cricket is a small peaked structure built on the upslope side of a chimney or wall to divert water around the obstacle. It's different from a valley but uses similar flashing principles. Required by code on chimneys wider than 30 inches; commonly missing on older Ohio homes. We add crickets during roof replacements where they're missing — the cost is small and the leak prevention is significant.
Free Inspection
Most valley problems are cheaper to catch early than to fix after they leak through to the ceiling. We do free written inspections that document the condition of every valley, the underlying ice shield, and the surrounding shingles.
Call (440) 645-2003 or request a free inspection. 9+ years rebuilding valleys across Northeast Ohio.