Roof Valley

Wherever two roof slopes meet at an inward angle (the opposite of a ridge), you have a valley. Valleys are where the most water runs during a rainstorm — sometimes 4-5× the volume that hits any other part of the roof. They're also where most leaks happen if installation cuts corners. Three valley installation methods: **Open valley.** Metal valley flashing (galvanized, copper, or color-matched aluminum) installed in the valley, with shingles trimmed back 4-6 inches from each side. Water runs down the exposed metal. Cleanest look, most durable, most expensive. **Closed-cut valley.** Shingles run continuously up one side of the valley, with shingles from the other side trimmed at the centerline. Common in mid-range installs. Looks tight, performs well if cut accurately. **Woven valley.** Shingles from both sides woven over each other. Traditional method, looks textured. Falling out of favor — woven valleys tend to wear faster than closed-cut and trap leaves. Always require valley underlayment (60" wide ice-and-water shield) regardless of method. The single biggest cause of valley leaks is missing or thin underlayment — even competent installers sometimes skimp because the shingles cover the evidence. For estimating: valleys aren't usually a separate line item but they should drive your complexity multiplier. A roof with 4+ valleys takes meaningfully longer to install and has 2-3× the callback rate of a simple gable. SatelliteQuotes flags valleys during the AI trace so you can adjust your complexity multiplier before sending the quote.