What Are the Different Types of Roofs for Commercial Properties?

In the world of commercial real estate, the roof is one of the most critical components of a building’s structure. It protects the entire facility from the elements, impacts energy efficiency, and can significantly affect maintenance costs. For building owners, understanding the various types of commercial roofing systems is essential for making informed decisions about construction, maintenance, and renovation.

This article explores the most common types of commercial roofs, their characteristics, advantages, and disadvantages, providing building owners with comprehensive insights to guide their roofing decisions.

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Built-up Roofing (BUR) Systems

Often referred to as “tar and gravel” roofs, Built-up Roofing (BUR) systems have been a staple in commercial roofing for over a century. These roofs consist of multiple layers of bitumen and reinforcing fabric, typically finished with a top layer of stone or gravel. BUR systems are known for their excellent waterproofing properties and high durability, making them a reliable choice for buildings with flat or low-slope roofs.

The advantages of BUR systems are numerous. They provide superior waterproofing due to their multiple layers, offer excellent fire resistance, and can last for decades with proper maintenance. The gravel top layer provides good UV protection and increases the roof’s fire resistance. Additionally, BUR roofs are highly resistant to foot traffic, making them ideal for roofs that require frequent access for maintenance of HVAC or other rooftop equipment.

However, BUR systems are not without their drawbacks. The installation process is labor-intensive and can be time-consuming, potentially leading to higher initial costs. These roofs are also significantly heavier than other options, which may require additional structural support, especially in older buildings. The use of hot tar during installation can create strong odors, which might be disruptive to building occupants. Lastly, identifying and repairing leaks in a BUR system can be challenging due to its multi-layer structure.

Single-ply Membrane Roofing

Single-ply membrane roofing has gained significant popularity in recent years due to its flexibility, ease of installation, and variety of options. The most common types of single-ply membranes are Thermoplastic Polyolefin (TPO), Ethylene Propylene Diene Monomer (EPDM), Polyvinyl Chloride (PVC), and Ketone Ethylene Ester (KEE).

Thermoplastic Polyolefin (TPO)

TPO is currently the most common type of commercial roofing material, and for good reason. It features a white reflective surface that enhances energy efficiency by reflecting sunlight and reducing cooling costs. TPO membranes offer good resistance to UV radiation and some chemicals, making them suitable for a wide range of environments.

The advantages of TPO roofing include its cost-effectiveness, energy efficiency, and ease of installation. TPO roofs are lightweight, reducing the structural load on buildings. They’re also resistant to tears, impacts, and punctures. Most TPO roofs come with a 20-year warranty, providing building owners with long-term peace of mind.

However, TPO roofing is not without its challenges. Over time, surface deterioration can occur due to UV exposure and extreme weather conditions. In areas prone to hail (like Austin) TPO roofs may be more susceptible to damage compared to more durable options. Additionally, the seams in TPO roofing can be vulnerable points for potential leaks, especially as the roof ages.

Ethylene Propylene Diene Monomer (EPDM)

EPDM roofing is known for its excellent durability and flexibility. These roofs are resistant to UV radiation and ozone, making them a long-lasting option for commercial buildings. EPDM is available in black or white, with black being the more common and economical choice.

The primary advantages of EPDM roofing include its long lifespan, low maintenance requirements, and excellent resistance to extreme weather conditions. EPDM roofs can last 25 to 30 years with proper care. They’re also highly flexible, allowing them to withstand building movement and temperature fluctuations without cracking or splitting.

On the downside, black EPDM roofs can absorb a significant amount of heat, potentially increasing cooling costs in warmer climates. While EPDM is generally puncture-resistant, it can be vulnerable to damage from sharp objects. Repairs on EPDM roofs can be challenging, as the material doesn’t easily accept coatings or adhesives after prolonged exposure to the elements.

Firestone Rubber Roofs

Firestone rubber roofs, a specific brand of EPDM (Ethylene Propylene Diene Monomer) roofing, have been a popular choice for commercial buildings for several decades. These roofs are particularly common on older structures, having gained widespread use in the 1980s and 1990s due to their durability and cost-effectiveness.

Firestone rubber roofs are known for their flexibility and resistance to UV radiation and ozone. They can withstand extreme temperature fluctuations without cracking or becoming brittle, making them suitable for a wide range of climates. The rubber material is also resistant to many forms of chemical pollution, acid rain, and other environmental factors that can damage roofing systems.

Many Firestone rubber roofs installed on older buildings are now approaching or exceeding their expected lifespan. As these roofs age, they become more susceptible to problems such as shrinkage, which can cause the membrane to pull away from walls, flashings, and other roofing elements. This can lead to leaks and water damage if not addressed promptly.

The aging of these roofs also makes them more vulnerable to punctures and tears. While EPDM roofs are generally puncture-resistant when new, the material can become less flexible and more brittle over time.

For building owners with older Firestone rubber roofs, it’s crucial to have the roof inspected regularly by a qualified professional. These inspections can identify signs of aging and potential problems before they lead to significant damage. Common issues to look out for include:

Seam failures, where the adhesives used to join sections of the roof membrane have degraded
Shrinkage of the membrane, which can cause it to pull away from walls and flashings
Punctures or tears in the membrane, which may be caused by foot traffic, falling debris, or extreme weather events
Blistering or bubbling of the membrane, which can indicate trapped moisture or loss of adhesion

Firestone Roof Blistering | Types of Roofs Commercial

Blistering on a Firestone roof.

In many cases, older Firestone rubber roofs will need to be replaced rather than repaired. While patches and coatings can extend the life of the roof temporarily, they often prove to be short-term solutions. Complete replacement allows building owners to take advantage of newer, more energy-efficient roofing technologies that have been developed since their original Firestone roof was installed.

Polyvinyl Chloride (PVC)

PVC roofing is highly regarded for its strong resistance to chemicals and fire. This makes it an excellent choice for restaurants, industrial facilities, or any buildings where the roof might be exposed to grease, chemicals, or other potentially harmful substances.

The advantages of PVC roofing include its durability, fire resistance, and ability to withstand pooling water. PVC roofs are highly reflective, contributing to energy efficiency. They also have heat-welded seams, which are stronger than the base material itself, reducing the risk of seam failure.

However, PVC roofing tends to be more expensive than TPO or EPDM. It can also become brittle in very cold temperatures, potentially leading to cracks. Some building owners may have concerns about the environmental impact of PVC production and disposal, although many manufacturers now offer recycling programs for old PVC roofing materials.

Ketone Ethylene Ester (KEE)

KEE is a high-performance thermoplastic that’s gaining popularity in the commercial roofing market. It offers enhanced chemical resistance compared to standard PVC and superior long-term weatherability. Many KEE roofs come with a 40-year warranty, double the typical warranty of TPO roofs.

The advantages of KEE roofing are significant. It’s highly durable and resistant to punctures, making it ideal for harsh environments or weather. KEE roofs are oil-resistant, making them an excellent choice for buildings with restaurant exhaust systems or industrial processes on the roof. They also maintain their flexibility over time better than standard PVC, reducing the risk of cracks in cold weather.

The primary disadvantage of KEE roofing is its higher upfront cost. However, many building owners find that the long-term benefits and extended warranty justify the initial investment. KEE roofing also requires specialized installation, which may limit the number of qualified contractors available for installation and repairs.

Modified Bitumen Roofing

Modified bitumen roofs combine the traditional reliability of BUR with added elasticity from polymer reinforcement. These roofs consist of reinforced roof fabrics and bitumen modified with polymers, available in torch-applied, self-adhered, or cold adhesive-applied options.

The advantages of modified bitumen roofing include good low-temperature flexibility and high strength. These roofs are suitable for various climate conditions and can be more puncture-resistant than some single-ply options. Self-adhered versions perform particularly well in high-wind environments, reducing the risk of roof damage during storms.

However, modified bitumen roofs require regular maintenance to ensure seam integrity. The dark color of many modified bitumen roofs can absorb heat, potentially increasing cooling costs. While generally more affordable than BUR systems, they may be more expensive than some single-ply options.

Metal Roofing

Metal roofing is known for its longevity and is particularly popular in industrial settings. Available in various materials such as steel, aluminum, and copper, metal roofs offer excellent durability and weather resistance.

The advantages of metal roofing are numerous. These roofs can last 40 to 60 years with proper maintenance, significantly longer than most other roofing options. They’re highly energy-efficient due to their high solar reflectance, potentially reducing cooling costs. Metal roofs are also fire-resistant and can withstand extreme weather conditions, including high winds and heavy snow loads.

The primary disadvantage of metal roofing is its higher upfront cost. However, many building owners find that the long-term savings in energy costs and reduced maintenance needs offset this initial investment. Metal roofs can be noisy during rain or hailstorms, which may be a concern for some buildings. They may also require additional insulation for optimal energy efficiency, adding to the overall cost.

Green Roofs

Green roofs, featuring vegetation over a waterproof membrane, offer unique benefits to building owners and the environment. These roofs consist of a waterproof membrane, growing medium, and vegetation, providing additional insulation and reducing the urban heat island effect.

The advantages of green roofs extend beyond the building itself. They can help manage stormwater runoff, improve air quality, and create habitats for local wildlife. For building owners, green roofs can provide energy savings through improved insulation and can extend the lifespan of the underlying roofing membrane by protecting it from UV radiation and temperature fluctuations. Green roofs may also qualify for tax incentives or contribute to environmental certifications like LEED.

However, green roofs come with their own set of challenges. They have a higher upfront cost and require more maintenance than traditional roofing systems. The increased weight of the soil and vegetation necessitates specialized design and may require additional structural support. Not all buildings are suitable for green roofs, and improper installation can lead to significant issues such as root penetration or water damage.

Spray Polyurethane Foam (SPF) Roofing

SPF roofing provides seamless coverage and excellent insulation properties. Applied as a liquid that expands into a foam, it creates a solid layer across the roof that can conform to various roof shapes and substrates.

The primary advantages of SPF roofing are its superior insulation properties and ability to create a seamless, monolithic roof surface. This eliminates the risk of seam failure and can significantly reduce energy costs. SPF roofing is lightweight, adding minimal load to the structure, and can be applied over existing roofing in many cases, saving on tear-off and disposal costs.

However, SPF roofing requires highly skilled application. Improper installation can lead to significant issues, including poor adhesion, uneven surfaces, or off-ratio foam that fails to cure properly. SPF roofs also require regular maintenance and recoating to protect the foam from UV degradation. The initial cost of SPF roofing can be higher than some other options, although this may be offset by energy savings over time.

Maintenance and Longevity Considerations

Regardless of the roofing type chosen, proper maintenance is crucial for ensuring longevity and performance. Building owners should implement a regular maintenance program with their building engineers and also schedule bi-annual professional inspections to identify and address issues early. Proper drainage is also essential for all roof types to prevent water pooling and potential leaks.

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Different roofing materials react differently to UV exposure, temperature fluctuations, and extreme weather events. In areas prone to severe weather, such as hailstorms, more durable options like KEE might be preferable. Building owners should also be aware of city regulations that often limit the number of roof layers to two before a complete tear-off is required (check your city’s building code to ensure you know the regulations in your area). This should be factored into long-term maintenance planning.

Warranty terms are another important consideration. While a TPO roof might come with a 20-year warranty, a KEE roof could offer up to 40 years of coverage. However, it’s crucial to understand what these warranties cover and what maintenance is required to keep them valid.

Conclusion

Choosing the right commercial roofing system involves balancing initial costs, long-term performance, maintenance requirements, and environmental considerations. While TPO remains the most common choice due to its cost-effectiveness and decent performance, materials like KEE are gaining traction for their superior durability and longer warranties.

Building owners should work closely with roofing professionals and consider factors such as local climate, building use, and long-term plans when selecting a roofing system. By understanding the advantages and disadvantages of each roofing type and implementing a robust maintenance program, building owners can make informed decisions that protect their investment and ensure the longevity of their commercial buildings.

Contact us today to discover how our property management team and building engineers can help you ensure the longevity of your building’s commercial roof.

Built-up Roofing (BUR) Systems