Hot Tar Roofing: Still a Good Option for Your Commercial Building?

5/6/2025

Hot Tar Roofing: Still a Good Option for Your Commercial Building?
When it comes to commercial roofing systems, few have the legacy and proven performance of hot tar roofing. Also known as built-up roofing (BUR), this traditional flat roof system has been used for well over a century on commercial buildings throughout the United States--including here in Detroit. At Motor City Roofers, we’ve installed, repaired, and maintained countless hot tar roofs, and one question we often hear from property owners is: “Is hot tar roofing still a good option for my building today?”

The answer is: it depends. While hot tar roofing still offers many advantages, there are also newer technologies and materials that might be more suitable for certain situations. In this article, we’ll explore the strengths, weaknesses, and ideal use cases for hot tar roofing, helping you decide whether it’s the right fit for your commercial building.

What is Hot Tar Roofing?Hot tar roofing, or built-up roofing, consists of alternating layers of bitumen (usually coal tar or asphalt) and reinforcing fabrics like fiberglass or roofing felt. These layers are “built up” to create a durable, waterproof membrane. Typically, a layer of gravel or a reflective coating is applied on top to protect the surface from UV rays and foot traffic.

Advantages of Hot Tar Roofing
1. Proven Durability
Hot tar roofing has a long track record of reliability. When properly installed and maintained, a BUR system can last 20–30 years or more. Its multi-layered structure offers excellent protection against water intrusion and general wear and tear.

2. Excellent Waterproofing
The multiple layers of bitumen and felt create a nearly impenetrable barrier against moisture. This is especially important in Detroit’s climate, where freeze-thaw cycles and heavy snow can wreak havoc on less robust roofing systems.

3. Fire Resistance
The gravel top layer commonly used on BUR roofs provides a level of fire resistance, which can be a valuable safety feature for industrial or densely packed commercial zones.

4. UV Protection
The surface gravel or reflective coatings protect the roof from damaging ultraviolet radiation, which extends the lifespan of the materials underneath.

5. Cost-Effective Over Time
While initial installation can be labor-intensive, the longevity and low maintenance requirements of hot tar roofing make it a cost-effective solution over the life of the roof.

Challenges and Drawbacks of Hot Tar Roofing
1. Heavy and Labor-Intensive Installation
Installing a BUR system is physically demanding and time-consuming. It requires heating tar to high temperatures (often 400°F or more) and using specialized crews. This can increase labor costs and cause logistical challenges, especially in tight urban settings.

2. Health and Safety Concerns
Hot tar produces strong fumes and poses a risk of burns or fire during installation. Safety precautions are necessary, and building occupants may be affected by the smell or smoke during the process.

3. Not Ideal for All Buildings
Because of the weight of the multiple layers, not every commercial roof is structurally capable of supporting a BUR system without reinforcement. Lightweight or older buildings might not be good candidates.

4. Maintenance Can Be Tricky
While BUR systems are generally low-maintenance, when repairs are needed, they can be difficult to diagnose and fix due to the layered structure. Leaks often travel within the system before surfacing, making them harder to locate.

Comparing Hot Tar Roofing to Modern Alternatives
TPO (Thermoplastic Olefin)
TPO is a popular single-ply roofing system known for its energy efficiency and relatively easy installation. While TPO roofs reflect UV rays well and are environmentally friendly, they don’t have the multi-layer protection of BUR.

EPDM (Ethylene Propylene Diene Monomer)
EPDM rubber roofing is durable and flexible, especially in cold weather. However, it may be more susceptible to punctures and doesn’t offer the same fire resistance as a BUR system.

Modified Bitumen
A close cousin of BUR, modified bitumen uses pre-fabricated sheets of asphalt modified with polymers. It offers some of the benefits of hot tar without the need for open flames or boiling tar.

Metal Roofing
Metal roofing systems are highly durable, fire-resistant, and can last over 40 years. However, they often come at a higher upfront cost and may not be suitable for all flat roof applications.

When Hot Tar Roofing Still Makes SenseAt Motor City Roofers, we recommend hot tar roofing in the following situations:

Large Commercial or Industrial Buildings:
Especially in Detroit’s manufacturing and warehousing sectors, BUR remains a solid choice due to its toughness and longevity.
Roofs With Heavy Foot Traffic:
If your roof is regularly accessed for maintenance or equipment checks, the gravel surface of a BUR system can withstand wear better than many single-ply options.
Flat or Low-Slope Roofs:
BUR is most effective on roofs with minimal pitch, where water pooling is a concern.
Budget-Conscious Long-Term Planning:
For property owners looking for a lower total cost of ownership and willing to invest in quality installation, BUR offers an excellent ROI over time.

Key Considerations Before Choosing Hot Tar RoofingIf you’re considering a hot tar roof for your commercial building, ask yourself the following:

Is your building structurally capable of supporting a heavy roof system?
Can you accommodate the installation time and safety precautions required for hot tar?
Do you have access to experienced installers like Motor City Roofers who specialize in BUR systems?
Is long-term durability more important than upfront cost or installation speed?

Final Verdict: Is Hot Tar Roofing Still a Good Option?
Yes--when used in the right context, hot tar roofing remains a durable, reliable, and cost-effective commercial roofing solution. It’s particularly well-suited to industrial buildings, large commercial spaces, and facilities that require maximum protection from water, UV rays, and fire.

However, it’s not the best fit for every situation. With modern alternatives like TPO, EPDM, and modified bitumen offering easier installation and lighter weight, building owners should carefully evaluate their specific needs, goals, and budget.

At Motor City Roofers in Detroit, we specialize in all commercial roofing types and can help you weigh the pros and cons of each option. Whether you’re building new, replacing an old roof, or considering a restoration, we’ll help you make the right choice for your building and your bottom line.

Contact Motor City Roofers today for a free commercial roof assessment or to learn more about our hot tar roofing services in the Detroit metro area.

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