Modified bitumen roofing is a popular choice for flat or low-slope roofs, combining asphalt with modifiers for durability and flexibility. Ponding water occurs when water collects and remains on the roof surface instead of draining off promptly. This usually happens because of improper roof design, clogged drains, or settled areas where the roof deck dips. Over time, standing water can degrade the modified bitumen membrane, potentially causing blistering, cracking, or leaks. To diagnose ponding issues yourself, after a rain, inspect the roof for visible puddles that linger for more than 48 hours. Also check gutters and drains for debris or blockages that could prevent proper water flow. These simple visual checks are safe for most homeowners and can help identify whether water isn’t draining as it should.
If ponding water is present, minor blockages can sometimes be cleared safely by homeowners to improve drainage. However, significant ponding often means there is a problem with the roof slope or drainage design that needs professional attention. A qualified roofer can assess the roof’s structural conditions, identify low points, and recommend fixes such as adding tapered insulation or improving drainage systems. When hiring a contractor, it’s smart to ask: “How will your solution ensure water drains promptly to prevent future ponding?” and “What measures do you take to maintain the integrity of the modified bitumen coating during repairs?” Since warranties can be voided if improper repairs are made, having a roofer familiar with modified bitumen systems is key for a safe, lasting fix.