Synthetic slate roofing is designed to mimic the look of natural slate while offering lighter weight and increased durability. However, ponding water can be a concern as it means water is standing on your roof for extended periods rather than draining off quickly. This often happens due to insufficient roof slope, clogged gutters, or poor drainage design around valleys and flat areas. Since synthetic slate is generally resistant to water damage, ponding itself might not cause immediate damage but can accelerate wear, promote algae growth, and over time may compromise the underlayment or flashing. Simple DIY checks include visually inspecting for flat spots, ensuring gutters and downspouts are clear and intact, and looking for signs of moss or algae buildup that indicates moisture retention. Running a garden hose along the roof during a light drain test can reveal slow-draining areas or blocked water paths.
If you notice persistent ponding greater than 30 minutes after rain or water that regularly pools above the surface level, it’s wise to call a professional roofer. A contractor can evaluate whether the roof pitch is adequate or if there are structural issues causing depressions. When consulting with a roofer, ask whether the synthetic slate installed is rated for your roof’s drainage requirements and if the underlayment and flashings are designed to withstand occasional moisture exposure. Also, inquire about recommended maintenance routines to prevent debris buildup that worsens ponding. Fixes might include re-sloping, adding tapered insulation, improving drainage channels, or installing additional scuppers or drains depending on your roof’s layout. Addressing ponding early helps protect both the synthetic slate and the roof’s overall integrity.