Detailing valleys on concrete tile roofs involves careful techniques to ensure water flows properly without causing leaks. In a woven valley, tiles from both sides are alternately overlapped across the valley, creating a visually continuous pattern but requiring precise installation to avoid gaps where water can seep in. Closed-cut valleys use a metal flashing — typically aluminum or galvanized steel — installed beneath the tile edges on one side of the valley, with the tiles on the opposite side overlapping the flashing. This method offers good water control but relies on the metal to channel runoff effectively. Open metal valleys expose a wide metal flashing down the center, with tiles neatly trimmed on both sides. This design handles heavy water flow well but the metal must be treated or painted to resist corrosion, especially with concrete tiles staying damp for longer periods.
To check valley details at home, start by looking during or right after a rain to spot any water backing up or pooling near the valley, which indicates poor flow or blockage. Inspect the flashing edges where they meet tiles to see if there are gaps, cracks, or rust spots that need repairing. If you notice missing or cracked tiles, or suspect improper installation like haphazard weaving or uneven flashing, it’s time to call a roofing contractor. When discussing valley work with a roofer, ask if they use corrosion-resistant metal flashing compatible with concrete tiles and whether installation follows manufacturer guidelines, as improper detailing could void tile warranties. Also, inquire about how they ensure valley waterproofing during installation, as valleys are common leak points and good detailing is crucial for long-term roof performance.