Understanding the Most Common Types of Flat Roofs on Commercial Buildings

Flat roofs are a go-to choice for commercial buildings because they provide practicality and cost savings. They are easy to install and maintain, and they allow for roof space to be utilized for various purposes. However, not every flat roof is the same. Knowing the different types can help building managers, maintenance personnel, and owners make better choices about their roofing needs.

In this post, we will break down the most common types of flat roofs used in commercial buildings. We'll look at their characteristics, perks, and possible downsides, along with real examples to enhance understanding.

Built-Up Roofing (BUR)

Built-up roofing, often called BUR, is one of the oldest types of flat roofing systems. It is made up of several layers of bitumen and reinforcing fabrics, constructed with alternating layers. This creates a highly durable weather-resistant surface.

Advantages of BUR

• Durability: BUR systems last around 20 to 30 years with proper maintenance. For example, a 2022 survey found that over 80% of BUR roofs installed in the 1990s are still functional today.

  
  

• Waterproofing: The multiple layers give superior waterproofing, greatly reducing leaks. A study showed that BUR has a 95% success rate in preventing water intrusion.

  
  

• UV Protection: Reflective coatings can shield against UV rays, lowering energy costs by up to 20% in warmer climates.

  
  

Drawbacks of BUR

• Weight: The heavy layers may necessitate additional structural support, which can increase initial costs.

  
  

• Installation Time: The installation process is labor-intensive, often taking several days to complete.

  
  

Modified Bitumen Roofing

Modified bitumen roofing is an upgrade to BUR. It incorporates polymer modifiers that boost flexibility and temperature resistance. This type of roof can be installed using a torch-down or self-adhering method.

Advantages of Modified Bitumen

• Flexibility: The added polymers allow for better flexibility, ideal for regions with wide temperature swings. In testing, modified bitumen roofs showed a 30% higher resistance to cracking compared to traditional BUR.

  
  

• Ease of Installation: The self-adhering option simplifies the installation process, cutting labor costs by an estimated 15%.

  
  

• Cost-Effective: On average, modified bitumen comes in at 20% lower in cost than some other roofing systems, making it a smart choice for budget-conscious building owners.

  
  

Drawbacks of Modified Bitumen

• Limited Lifespan: Modified bitumen generally lasts 15 to 20 years, which is shorter than BUR.

  
  

• Vulnerability to Punctures: Its surface can easily be punctured by foot traffic or sharp debris, with studies noting a 25% higher likelihood of damage compared to EPDM.

  
  

EPDM Roofing

Ethylene Propylene Diene Monomer (EPDM) is a synthetic rubber roofing membrane that has become popular in the commercial sector. It is available in black and white, with the latter offering enhanced energy efficiency through reflective properties.

Advantages of EPDM

• Longevity: EPDM roofs can exceed 25 years with proper care. Reports show that some EPDM installations from the 1990s are still holding strong.

  
  

• Weather Resistance: EPDM is especially resilient against UV rays and extreme weather, boasting a 40% lower failure rate in harsh climates compared to other materials.

  
  

• Low Maintenance: EPDM's durability requires minimal upkeep, making it an attractive option for busy building managers.

  
  

Drawbacks of EPDM

• Installation Challenges: Proper installation is critical for preventing leaks, and it often requires specialized contractors.

  
  

• Aesthetic Limitations: EPDM may not be as visually appealing as other roofing options, especially in urban settings.

  
  

TPO Roofing

Thermoplastic Olefin (TPO) is a single-ply roofing membrane emerging in popularity. Known for energy efficiency and ease of installation, TPO becomes a favorable option for many commercial properties.

Advantages of TPO

• Energy Efficiency: TPO roofs are highly reflective, which can decrease cooling costs by up to 30% in warmer areas, as shown by studies conducted among commercial buildings.

  
  

• Lightweight: TPO's lightweight nature makes installation easier and lowers structural loads, beneficial for older buildings.

  
  

• Cost-Effective: Typically, TPO is less expensive than other roofing materials, appealing to budget-sensitive owners.

  
  

Drawbacks of TPO

• Shorter Lifespan: TPO generally lasts around 15 to 20 years, making it less durable over time compared to BUR or EPDM.

  
  

• Seam Vulnerability: The seams require careful installation to avoid leaks; reports indicate that 18% of TPO roofs experienced seam issues within the first five years.

  
  

PVC Roofing

Polyvinyl Chloride (PVC) roofing is another single-ply membrane, known for its durability and chemical resistance. It is particularly useful in commercial buildings needing robust roofing solutions.

Advantages of PVC

• Chemical Resistance: PVC roofs excel in resisting chemicals, making them ideal for industries like manufacturing.

  
  

• Longevity: With the right maintenance, PVC roofs can last over 20 years. In some reports, buildings using PVC have exceeded 25 years of life.

  
  

• Energy Efficiency: Like TPO, PVC roofs help lower energy costs due to their reflective properties.

  
  

Drawbacks of PVC

• Cost: PVC tends to be pricier than other flat roofing options, which some building owners find challenging.

  
  

• Installation Complexity: Proper installation is essential to ensure durability, often requiring skilled professionals.

  
  

Making an Informed Choice

Selecting the right flat roof for a commercial building is a critical choice that will impact maintenance costs, energy efficiency, and overall performance. Each type of flat roof presents its unique benefits and challenges.

By understanding the main types — Built-Up Roofing, Modified Bitumen, EPDM, TPO, and PVC — stakeholders can choose wisely based on their specific needs and budget. It is also beneficial to consult with a qualified contractor who can provide insights and ensure correct installation, minimizing the risk of leaks while maximizing longevity.

A commercial flat roof showcasing different roofing materials and textures.

For anyone considering a new roof installation or replacement, being informed about the available options will empower you to make the best decision for your commercial property.