A Handy Guide to Commercial Flat Roofing Options – Part 3: The Built-Up Roof

Ever wondered why some roofs are covered in gravel? Well, that is what you call a built-up roof.

What It Is

Built-up roofing is a traditional system that has been around since the 1840s. It is called such because it is made up of built-up layers of bitumen and reinforcing fabrics. A four-ply system, for instance, will feature a four-layer roofing membrane. Base sheets, the bottommost layer, can sometimes be mechanically attached to a roof. If a BUR is directly applied to insulation or roof decks, it is considered as being fully adhered.

What Makes It a Great Choice?

  • BUR is highly durable, thanks to being made with several layers of material. This same feature also gives the flat roof excellent protection against leaks, allowing it to prevent moisture damage.
  • Aggregate like gravel, mineral granules or slag covers the topmost portion of the roofing system, beefing up protection against impact. This makes the roof ideal in hail-prone areas.
  • Depending on the surfacing (aggregate, coatings or cap sheets) used, a BUR can reflect back a considerable amount of heat, reducing what a building absorbs to stabilize indoor temperature. This not only assures comfort but can help in cutting back on energy costs as well.
  • BUR is flat and solid, heavy enough to resist high winds and maintain its shape.
  • It’s not unheard of for BURs to last 20 to 30 years. Given the long service life it offers, BUR makes for a great investment as it ensures you make the most out of your purchase.
  • Plus, maintenance is easy. Aside from a routine check for wear and tear, most of the work involves just cleaning up debris that has accumulated on the roof.

Did you know?

A BUR with two or three layers topped by a polymer-modified bitumen cap sheet is called a “hybrid” system. The National Roofing Contractors Association, however, counts this roofing system as a modified-bitumen type.

This concludes our three-part blog series on commercial flat roofing options! We hope learning more about single-ply roofs, modified bitumen roofing, and BURs has helped you in figuring out what flat roof would best address your needs. Don’t forget to consult with your local roofing contractor for assistance!