Total Construction Services

Menu

Modified Bitumen Roofing

Modified bitumen roofing is a type of asphalt-based roofing material designed for low-slope or flat roofs. It combines the reliability of traditional built-up roofing (BUR) systems with modern materials and technology, offering excellent durability, flexibility, and weather resistance. Here’s an in-depth look at its components, types, installation methods, benefits, and drawbacks:

Modified Bitumen Roofing Installation

Composition and Structure

Modified bitumen roofing systems are made of multiple layers, each serving a specific purpose:

  • Bitumen: A type of asphalt modified with polymers for enhanced flexibility and performance.
    • APP (Atactic Polypropylene): Adds plastic-like qualities for improved UV resistance and durability.
    • SBS (Styrene-Butadiene-Styrene): Adds rubber-like flexibility, making it less likely to crack in cold weather.
  • Reinforcement Layer: Typically polyester, fiberglass, or a combination of both, providing tensile strength and resistance to tearing.
  • Surface Layer: Protects the roof from weather, UV rays, and physical damage. Options include:
    • Granulated surface for UV and impact resistance.
    • Smooth surface for additional coatings or painting.
    • Foil-faced surfaces for reflectivity and energy efficiency.

2. Types of Modified Bitumen Roofing

Modified bitumen roofs can be categorized based on the polymer used and installation method:

  • APP-Modified: Known for its UV resistance and durability; often torch-applied.
  • SBS-Modified: Flexible in low temperatures and ideal for regions with harsh winters; installed with adhesives or cold-applied methods.

3. Installation Methods

  • Torch-Applied: A torch heats the underside of the bitumen, melting it to adhere to the substrate or previous layers. Common with APP-modified bitumen.
  • Cold-Adhesive Application: Adhesives are used to bond the material to the roof, avoiding the need for open flames.
  • Self-Adhesive: A peel-and-stick backing simplifies installation, requiring no heat or additional adhesives.
  • Mechanically Attached: Fasteners secure the sheets, often in conjunction with adhesive layers.

4. Benefits

  • Durability: Resistant to physical damage, cracking, and weathering.
  • Flexibility: SBS-modified bitumen remains pliable in cold climates, reducing the risk of thermal stress.
  • UV and Weather Resistance: Especially true for APP-modified bitumen, which offers long-lasting protection against sunlight and heat.
  • Ease of Repair: Can be patched or repaired relatively easily if damaged.
  • Cost-Effective: Offers a good balance of performance and affordability compared to other roofing systems.
  • Compatibility: Works well with many roof substrates and insulation types.

5. Drawbacks

  • Installation Complexity: Torch-applied systems require skilled labor and can pose fire risks if not handled properly.
  • Maintenance: While durable, regular maintenance is necessary to ensure long-term performance.
  • Weight: Heavier than some single-ply roofing systems, which may require additional structural support.
  • Energy Efficiency: Without reflective coatings, traditional bitumen roofs can absorb heat, increasing cooling costs.

6. Typical Applications

Modified bitumen roofing is commonly used in:

  • Commercial and industrial buildings with flat or low-slope roofs.
  • Residential buildings with low-pitch roofs.
  • Roofs requiring excellent durability in extreme weather conditions.

7. Lifespan and Maintenance

  • Lifespan: Typically lasts 15–20 years, but can reach up to 25–30 years with proper installation and maintenance.
  • Maintenance Tips:
    • Regular inspections for cracks, blisters, or tears.
    • Prompt repairs of damaged areas to prevent leaks.
    • Cleaning debris and ensuring drainage systems function properly.

8. Environmental Considerations

  • Recyclability: Some modified bitumen products can be recycled at the end of their lifecycle.
  • Reflective Options: White or reflective granules or coatings can improve energy efficiency by reducing heat absorption.


In summary, modified bitumen roofing is a versatile, durable, and time-tested option for low-slope roofing. With proper selection of materials and installation methods, it can provide long-lasting protection and performance in a wide range of climates.

Total Construction Services currently offers modified bitumen roofing in every state except for New York, including Puerto Rico. If you need a professional roofer in Missouri, Texas, Alabama, Florida, or the 49 other states, contact us for a quote!

 
REQUEST A QUOTE