Built-up Roofing (BUR)
Roof Online Staff
Built-up roof installation: Layers of roofing felts and hot-applied asphalt make up this built-up roof membrane. 
View of a gravel-surfaced built-up roof.
What is a Built-up Roof?
A built-up roof is a type of “flat” or low-sloped roof made up of multiple layers of bitumen (asphalt or coal tar pitch) and reinforcing felts.
Typical built-up roofs have three to five layers, called “plies”. Built-up roof systems typically have a layer of insulation under the waterproof bitumen membrane, as well as some sort of protective surfacing, most commonly gravel.
Other protective surfaces for built-up roofs include reflective roof coatings, asphalt emulsion coatings, sheets of modified bitumen, or some combination of these. When gravel is used, it usually adds about 3 to 4 pounds in weight per square foot to the roof system.
A built-up roof is frequently called a “BUR” in technical literature. The colloquial term “tar and gravel roof” refers to built-up roofs.
Related Pages
- Asphalt (Hot) Roofing
- Building Codes and Roofs
- Built-Up Roof System Manufacturers
- Coal Tar Pitch Roofing
- Modified Bitumen Roofing
Useful Links for Built-up Roofing Information
1. General: For an informative, in-depth general article about various roof systems, see this page at the Whole Building Design Guide site, which is maintained by the National Institute of Building Sciences.
2. Building Codes: “R905.9 Built-Up Roofs” from the International Residential Code and “1507.10 Built-Up Roofs” from the International Building Code. Both available on the UpCodes website.
3. Inspection and Maintenance of built-up roof systems: ROOFER: An Engineered Management System (EMS) for Bituminous Built-Up Roofs is an extremely detailed and valuable resource put together by the US Army Corps of Engineers’ Engineer Research and Development Center, and available at the Defense Technical Information Center website.
4. Safety: See this material safety data sheet for health and safety information about the roofing asphalt used in built-up roof systems at the Owens Corning website. This is only an example and other products and brands may be different.
5. Safety: See this material safety data sheet for health and safety information about coal tar pitch at the Durapax website. This is only an example and other products and brands may be different.
6. Safety: See this material safety data sheet for health and safety information about the interply felts used in built-up roof systems at the Johns Manville website. This is only an example and other products and brands may be different.
7. Technical: See this installation guide for insight into how a built-up roof system is put together. Provided by Johns Manville.
8. Manufacturers: A list of built-up roof system manufacturers can be seen here.
