Built-up roofing (BUR) is a popular flat roofing system made by layering multiple sheets of bitumen and reinforcing fabrics, then covering it with a protective surface like gravel or a reflective coating. Proper flashing details are crucial because flashings seal the edges where the roof meets walls, chimneys, or other penetrations, preventing water from seeping underneath the layers. Flashings for BUR roofs are typically installed by layering multiple plies of roofing felts with bitumen around the perimeter and up any vertical surfaces. This creates a continuous membrane that resists water infiltration. With built-up roofs, the key is ensuring the flashing extends several inches above the deck and is securely embedded into the base layers, often finished with a top layer of gravel or cap sheet for UV protection. Over time, flashing may crack or pull loose due to roof movement or weather exposure, leading to leaks.
If you want to perform a safe, simple DIY check, look for cracks, blisters, or missing gravel along flashing edges, and carefully examine any seams for wear or gaps—focus on areas where water pools after rain. Avoid walking on the roof if it’s hot or brittle, but if you can safely inspect from a ladder, use a flashlight to look underneath edges for signs of decay or water staining inside your attic near the flashing. If you notice damage, persistent leaks, or flashing that’s loose or pulling away, it’s time to call a professional roofer experienced with BUR systems. When consulting a contractor, good questions to ask include, "How do you ensure the flashing integrates fully with the BUR layers to maintain a continuous waterproof seal?" and "What warranty do you provide on flashing installation, and how do you handle roof movement or settling?" These questions help confirm the roofer’s expertise and the durability of their flashing method.