What is Built-Up Roofing and When Does It Make Sense for Houston Buildings

What is Built-Up Roofing?

Built-up roofing, commonly called BUR or a tar-and-gravel roof, is a multi-layer commercial roofing system that has been used in the United States for over 100 years. It is constructed by alternating layers of bitumen (asphalt or coal tar) with reinforcing fabric called ply sheets. The finished surface is typically covered with aggregate (gravel or slag) or a reflective cap sheet.

Despite the dominance of single-ply membranes like TPO in the current market, built-up roofing remains a relevant and durable option for specific commercial and industrial applications in Houston.

How Built-Up Roofing Performs in Houston

• Redundancy: Multiple layers mean a single membrane puncture or failure does not immediately result in a leak

• Impact resistance: The aggregate surface layer provides excellent protection against hail, foot traffic, and falling debris

• Fire resistance: BUR systems carry Class A fire ratings, making them suitable for applications with strict fire code requirements

• Proven longevity: Well-maintained BUR systems in Houston have service lives of 20 to 30 years

When Built-Up Roofing Is the Right Choice

BUR is particularly well-suited for Houston commercial and industrial buildings in these situations:

• High foot traffic roofs where HVAC technicians, contractors, or other trades regularly access the rooftop

• Industrial facilities with heavy rooftop equipment loads

• Buildings where fire resistance rating requirements exceed what single-ply membranes provide

• Reroofing projects where the existing BUR system is being built up with additional plies rather than torn off

• Buildings where the owner has a preference for the proven track record of a multi-layer system

Built-Up Roofing vs. Modified Bitumen in Houston

Modified bitumen is often considered a modern evolution of built-up roofing. Modified bitumen systems use asphalt modified with APP or SBS polymers that improve flexibility and performance at extreme temperatures. In Houston's heat, SBS-modified bitumen is generally preferred. The choice between traditional BUR and modified bitumen typically comes down to specific building requirements and contractor recommendation based on site conditions.

Mammoth Roofing Services installs and maintains built-up roofing systems for commercial and industrial properties across Houston. Contact us at 832-416-1566 or visit usmammoth.com.