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What Are Built-Up Roofs? (Materials, Installation, & More)

June 10, 2024 | 3 min. read

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Built-up roofs (BUR) are a popular and time-tested option when choosing the right roofing system for your commercial or industrial building. BUR systems are known for their durability and effectiveness and have been a staple in the roofing industry for over a century.

But, as with all roof types, Built-Up Roofs aren’t for everyone. So how do you know if they’re the right fit for you?

For over a decade, Rescue My Roof has been a leader in the roofing industry, helping thousands of homeowners find their perfect roofs. Today, we’re using our expertise to help you determine whether or not a Built-Up Roof is suitable for your home. 

This comprehensive guide will explore built-up roofs, their key components, advantages, installation process, and important considerations. Ultimately, you’ll know if one is in your future. 

Built-Up Roofs (BUR)

A Built Up Roof on a commercial building in Fort Worth, TX.

Built-up roofs, commonly referred to as BUR, are roofing systems consisting of multiple bitumen layers and reinforcing fabrics. These layers are alternated and then finished with a layer of aggregate, such as gravel or mineral granules, to provide added protection and durability. BUR systems are primarily used for flat or low-slope roofs, making them  popular for commercial and industrial buildings.

Critical Components of Built-Up Roofs

Built Up Roof diagram with labeled layers.
  • Bitumen Layers – Bitumen, which can be asphalt, coal tar, or cold-applied adhesive, acts as the waterproofing material. It is applied in layers, creating a durable and watertight seal.
  • Reinforcing Fabrics – Layers of reinforcing fabrics, such as fiberglass mats or organic felts, are embedded between the bitumen layers to strengthen and stabilize the roofing system.
  • Surfacing Materials – The top layer of a BUR system is often covered with gravel, mineral granules, or a reflective coating. This layer protects the bitumen from UV rays, physical damage, and weathering.

5 Advantages of Built-Up Roofs

  1. Durability: Built-up roofs are known for their long lifespan, often lasting 20 to 30 years or more with proper maintenance. The multiple layers provide excellent resistance to wear and tear.
  2. Waterproofing: The layered construction of BUR systems makes them highly effective at preventing water infiltration. The bitumen layers create a seamless, watertight membrane that can withstand ponding water.
  3. Fire Resistance: BUR systems are inherently fire-resistant due to the bitumen layers and the use of non-combustible surfacing materials. This makes them a safe choice for buildings in areas with strict fire codes.
  4. Cost-Effective: While the initial installation cost of a BUR system may be higher than some other roofing options, its durability and low maintenance requirements make it a cost-effective choice in the long run.
  5. Versatility: BUR systems can be applied to various roof types, including low-slope and flat roofs. They are also compatible with various insulation materials, enhancing their energy efficiency.

Installation Process

The installation of a built-up roof involves several key steps:

Roofing crew installing a Built Up Roof.
  1. Surface Preparation: The existing roof surface is cleaned and prepared to ensure proper adhesion of the bitumen layers. Any debris, old roofing material, or imperfections are removed.
  2. Application of Bitumen: Multiple layers of hot or cold-applied bitumen are spread over the roof surface. Each layer can cool and harden before the next layer is applied. The bitumen is typically reinforced with layers of roofing felt or fiberglass mats.
  3. Adding Reinforcement: Reinforcing fabrics are embedded within the bitumen layers to enhance the roof’s structural integrity. These fabrics are crucial for preventing cracks and leaks.
  4. Surfacing: Once the bitumen layers have cured, a final layer of gravel, mineral granules, or reflective coating is applied. This surfacing layer protects the roof from UV radiation, physical damage, and weathering.
  5. Curing and Inspection: The completed roof can be cured entirely, and a thorough inspection is conducted to ensure no defects or areas of weakness. Any necessary repairs or touch-ups are made before the roof is considered complete.

Things to Know Before Buying

  • Maintenance – Regular maintenance is crucial for the longevity of a BUR system. This includes inspections for damage, ponding water, and any signs of wear or deterioration.
  • Installation Costs – The initial cost of installing a BUR system can be higher than other roofing options. However, the long-term benefits and durability often justify the investment.
  • Climate Suitability – BUR systems perform exceptionally well in harsh weather conditions, including heavy rain, snow, and high winds. However, additional insulation and reflective coatings may be necessary in regions with extreme temperatures to enhance performance.
  • Permitting and Codes – Ensure your BUR installation complies with local building codes and regulations. Some areas may have specific requirements for roofing materials and installation methods.

Is A Built-Up Roof Right For You?

Built-up roofs (BUR) are a reliable and durable roofing solution, especially suited for commercial and industrial buildings. With their proven track record, strong waterproofing capabilities, and long lifespan, BUR systems are popular with many property owners. 

If you own a commercial building that needs a roof to withstand not only the test of time but also serious weather conditions, a BUR may be the best fit.

If a BUR isn’t an option, don’t fret. Learn more about other roofing systems with “Asphalt Shingles: The Cheapest Roof Type” and “EPDM vs. TPO Roofing: Which is Better?Do you need a roof replacement in southeastern Wisconsin? Rescue My Roof can help. Contact us today to get a free roof estimate.