Flat Roofing Systems for Commercial Buildings

When it comes to the infrastructure of commercial buildings, few elements are as critical as the roofing system. The choice of roofing material is not only a substantial investment but also a decision that impacts the building’s energy efficiency, maintenance costs, and ultimately, its longevity. For commercial property owners and facility managers, the quest for the ideal flat roofing system is akin to finding the cornerstone of their building’s structure. From navigating the nuances of Built-Up Roofs (BUR) to understanding the advances in Thermoplastic Polyolefin (TPO) and Ethylene Propylene Diene Terpolymer (EPDM) systems, each option offers a unique set of benefits and trade-offs.

In this comprehensive guide, we will shed light on the flat roofing systems that are reshaping the skylines of our urban, commercial landscapes. We’ll explore the intricacies of each system, walking you through the advantages, downsides, and considerations for your specific commercial property. By the end of this post, you’ll be well-equipped to make informed decisions that align with the needs and constraints of your business.

Built-Up Roofs (BUR)

Built-Up Roofing, or BUR, is a tried and true method that has been around for over a century. It involves layering multiple plies of roofing felts with bitumen, a sticky black viscous mixture of hydrocarbons. The finished product is a robust, multi-layered, flat roof that is resistant to weather and ultraviolet (UV) radiation.

Description and Construction

A BUR system typically consists of three main components: bitumen, which acts as a waterproofing agent and the adhesion element; reinforcing plies, to give the roof its strength and durability; and a surfacing material, which offers protection from the elements and UV rays. The system can be further fortified with aggregate or a reflective coating for added energy efficiency.

Pros and Cons


  • Proven longevity, often exceeding 20 years
  • High resistance to fire
  • Excellent waterproofing capabilities


  • Heavyweight, may require additional structural support
  • Labor-intensive installation process
  • Potential for unpleasant odors during application

Suitable Applications

BUR systems are ideal for low slope buildings, where waterproofing and weather resistance are a priority. They have been used in the past extensively for commercial and some industrial applications.

Thermoplastic Polyolefin (TPO) Roofs

TPO is a relatively new player with Oregon City commercial roofing contractors, having been developed as a single-ply membrane in the early 1990s. It is recognized for its energy-saving and reflective properties, along with its ease of installation.

Explanation of TPO Roofing

A TPO roof is a single-ply reflective roofing membrane made from polypropylene and ethylene-propylene rubber. This combination results in a durable, flexible sheet that can be mechanically attached, fully adhered, or even ballasted.

Advantages and Disadvantages


  • Lightweight, which can reduce the need for additional structural support
  • Solar reflective properties can help reduce energy costs
  • Resistant to UV, ozone, and algae growth


  • Some formulations can be less resistant to high heat and fire
  • Can be susceptible to mechanical damage during installation and maintenance
  • Shorter track record compared to BUR, so long-term performance data is still being collected

Ideal Uses and Considerations

TPO roofs shine in environments where the reflective surface can offer significant energy savings, such as in warmer climates or for buildings with extensive HVAC systems.

Ethylene Propylene Diene Terpolymer (EPDM) Roofs

EPDM is another single-ply membrane system, but it predates TPO, having been used in Portland commercial roofers since the 1960s. It is composed of a durable synthetic rubber material, making it a versatile choice for both new construction and re-roofing projects.

Overview of EPDM Roofing

EPDM is an ethylene propylene rubber mixed with a diene monomer, which allows for crosslinking within the polymer structure. This results in a highly durable, waterproof, and weather-resistant material.

Benefits and Drawbacks



  • Lower puncture resistance compared to some other systems
  • Darker colors can absorb more heat, leading to increased energy costs
  • Can shrink over time, particularly in circumstances with large temperature differentials

Applications and Maintenance Tips

EPDM roofs are commonly seen in commercial buildings with moderate climates. They’re relatively easy to maintain but do require proactive management to address potential shrinkage and punctures.

Comparison of Flat Roofing Systems

Understanding the differences between BUR, TPO, and EPDM systems is crucial when selecting the right system for your commercial property.

Contrasting Key Features, Costs, and Durability

  • BUR systems offer exceptional resistance and a proven track record, but are more costly to install and maintain.
  • TPO roofs are a middle ground, with relatively good durability and cost-effectiveness.
  • EPDM is the most budget-friendly option and is favored for its ease of installation, but may require more frequent maintenance.

Factors to Consider When Choosing a System

  • Consider the climate and the building’s location. This will impact the need for insulation, energy efficiency, and resistance to weather conditions.
  • Determine the specific use of the building. Industrial facilities may require more resilient roofing than an office building.
  • Assess long-term operational costs and potential energy savings that can be achieved with reflective membrane options like TPO.

Maintenance and Longevity

The key to maximizing the lifespan of any flat roofing system lies in regular maintenance and timely repairs.

Tips for Maintaining Flat Roofing Systems

  • Implement a routine inspection schedule, preferably twice a year or after severe weather events.
  • Keep drains and gutters clear to avoid water buildup and related issues.
  • Address any repairs promptly to prevent minor issues from escalating.

Strategies to Prolong the Lifespan of Commercial Roofs

  • Consider a recoating strategy as part of the maintenance plan, typically recommended every 5-10 years for TPO and EPDM roofs.
  • Conduct infrared moisture scans to detect hidden leaks and wet insulation.
  • Engage with a professional roofing contractor with a track record of expertise in commercial flat roofing.


The perfect flat roofing system for your commercial building is an amalgamation of reliability, energy efficiency, and long-term cost-effectiveness. Whether it’s the traditional stalwart BUR, the modern versatility of TPO, or the enduring value of EPDM, each system has a place in the vast tapestry of commercial construction. As you venture into the realm of roofing decisions, remember that an investment in quality roofing is an investment in the stability and success of your business. Choose wisely, maintain diligently, and enjoy the protection and performance that a superior roofing system affords.

In closing, commercial property owners and facility managers are encouraged to conduct thorough assessments, explore all options, and consult with industry professionals to ensure that the roofing system they select fulfills the unique demands of their commercial properties. Your roof is not just a shield against the elements; it’s a statement of your commitment to quality and reliability in all aspects of your business.