Detailing valleys on TPO roofs is essential to ensure water moves efficiently without causing leaks, especially when using woven, closed-cut, or open metal valley designs. TPO, a thermoplastic membrane, requires precise attention to seams and laps due to its heat-welded installation method. For woven valleys, the TPO sheets are interlaced over the valley area, allowing a natural water flow while maintaining membrane integrity. Closed-cut valleys involve cutting one membrane edge precisely along the valley centerline and folding it under the opposing sheet, minimizing exposed seams. Open metal valleys use a metal flashing, often galvanized steel or aluminum, installed in the valley with the TPO membrane heat-welded over its edges. These methods help manage water but differ in exposure and potential wear points.
You can inspect valleys for signs of wrinkling, poor seams, or dirt buildup, which can indicate potential issues. A safe DIY check involves looking for any visible seam separation, debris accumulation, or membrane distortion during dry weather. Avoid walking extensively in valleys as this can cause damage. If you notice bubbling, cracking, or consistent water pooling, it’s wise to call a professional roofer for a thorough assessment. When speaking with a contractor, ask: “How do you ensure the heat welds in the valley remain watertight over time, especially with temperature fluctuations?” and “What warranty coverage do you provide specifically for valley treatments on this TPO roof?” These questions help confirm the roofer’s technique and commitment to long-term performance.