Valleys on synthetic slate roofs play a crucial role in directing water off the roof and into the gutters, so detailing them properly is key to preventing leaks and prolonging roof life. There are three common valley types: woven, closed-cut, and open metal. Woven valleys interlock shingles from both sides over the valley line, creating a seamless and visually appealing look. Closed-cut valleys involve layering shingles from one side and cutting shingles on the opposite side back from the valley line, creating a clean edge. Open metal valleys use a metal flashing that sits in the valley groove, with shingles trimmed neatly against the metal. Synthetic slate can be cut similarly to natural slate, but it’s lighter and more flexible, so care should be taken to avoid cracking during installation. Simple diagnostics can be done by checking for gaps, loose shingles, or pools of water after rain, which might indicate poor valley detailing. Homeowners can perform a safe DIY inspection using binoculars or from a ladder for closer views, looking for damaged shingles, lifted areas, or signs of water infiltration inside the attic near valleys.
If water pooling or leaks are suspected around valleys, it’s best to call a professional roofer experienced with synthetic materials. Valleys are one of the most vulnerable areas on any roof, and improper repairs can void warranties or cause further damage. When consulting a contractor, ask if they follow the synthetic slate manufacturer’s installation specifications for valleys and whether they use compatible flashing materials that won’t cause corrosion or staining. Another important question is how they ensure a watertight seal in the valley while allowing for normal expansion and contraction of synthetic slate shingles. Properly detailed valleys combine good materials and skilled craftsmanship, and raising these questions helps ensure you get a durable, long-lasting roof with minimal issues.