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.

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Construction Definition - Built-Up Roof: A “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. A built-up roof is frequently called a “BUR” in technical literature. The colloquial term “tar and gravel” refers to built-up roofs.

Related Pages:

Useful Links:

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. SafetySee 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. SafetySee this material safety data sheet for health and safety information about coal tar pitch at the Durapax websiteThis is only an example and other products and brands may be different.

6. SafetySee this material safety data sheet for health and safety information about the interply felts used in built-up roof systems at the Johns Manville websiteThis 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. ManufacturersA list of built-up roof system manufacturers can be seen here.