Built-Up Roofing (BUR) / Tar & Gravel Repair

Built-up roofing consists of alternating layers of asphalt (or coal tar) and reinforcing felt, traditionally finished with a gravel surface for UV protection. This is the system most likely to still exist, in original or once-recovered form, on Downey homes built during the 1940s–60s construction boom — and it’s well past the point where age alone explains most of the leaks we see.

BUR repair generally follows the same principle as modified bitumen: clean and dry the area, apply flashing cement, embed a fiberglass reinforcing membrane, and top-coat with more cement, feathered into the surrounding gravel-surfaced roof. On gravel-surfaced roofs, the gravel around the repair area typically needs to be pulled back before work starts and reset afterward.

Because BUR systems this old have often had multiple prior repairs layered on top of each other over the decades, diagnosis matters even more here — what looks like a straightforward patch job can reveal several past repair attempts stacked on top of the original roof, some of which may be contributing to the current leak rather than solving a past one.