Built-Up Roofing (BUR) is a traditional flat roof system made from alternating layers of asphalt and reinforcing fabrics, topped with a protective surface like gravel or a coating. Ponding water occurs when water collects and remains standing on the roof instead of draining away. This usually happens because of poor roof design, clogged drains, or structural sagging where the roof deck bends or dips, preventing proper runoff. Over time, standing water can accelerate the breakdown of the roof materials, cause leaks, and promote mold growth. Homeowners can perform a simple visual check after rainfall to see if water pools persist for more than 48 hours, which indicates poor drainage. Checking that gutters and scuppers are clear and ensuring no debris blocks water flow are safe, straightforward steps anyone can take without climbing too high or risking injury.
If ponding water is present and doesn’t drain after these checks, it’s wise to call in a roofing professional. A roofer will assess the structural integrity of the roof deck and the BUR layers to recommend fixes such as adding tapered insulation to improve drainage, repairing or replacing damaged layers, or clearing or modifying drainage paths. When consulting a contractor, ask: “How will you ensure the roof slope allows water to flow freely and prevent future ponding?” and “What warranties cover repairs or replacements, especially related to water ponding and resulting damage?” Since many BUR systems have specific layering requirements, ensure any repair work respects the manufacturer’s guidelines to maintain your roof’s warranty and long-term performance.