A Built-Up Roof (BUR) is a traditional roofing method made of multiple layers of roofing felt alternated with bitumen (tar or asphalt), creating a durable, waterproof surface. When a homeowner or roofer considers BUR maintenance or replacement, the choice between overlaying a new BUR on top of the old one versus a full tear-off can be important. Overlay means installing the new layers directly over the existing BUR, saving time and labor but adding weight and potentially hiding underlying problems like water damage or deteriorated decking. A tear-off means removing all the old roofing down to the deck before installing a new BUR system, which allows for a thorough inspection of the roof’s structure, helping to avoid trapping moisture or rot. Overlay is usually faster and less expensive, but not always the best long-term choice especially if the existing BUR is close to the end of its lifespan or has damage beneath it.
To safely check if an overlay might work, you can inspect from the attic for signs of leaks, water stains, or sagging decking, as these indicate structural issues that need attention before adding more layers. Also, walk the roof carefully to feel for soft or uneven spots which hint at damage below the surface. Avoid climbing on the roof if you're unsure or the surface feels unstable. A good question to ask a contractor is, “Can you thoroughly inspect the decking under the current BUR without a full tear-off, and if not, what are the risks of an overlay in this case?” Another useful question is, “How will overlaying affect my BUR system warranty and what roofing code considerations must we keep in mind for an overlay?” Professional guidance helps ensure your roof remains solid and code-compliant without unexpected surprises.