Understanding Built Up Roofs: Advantages and Disadvantages of Low Slope Roofs in Tennessee
- Apr 5
- 4 min read
When choosing a roofing system for a low slope roof in Tennessee, one option that often comes up is the built up roof (BUR). This roofing style has been around for over a century and remains popular for commercial and some residential buildings. But what exactly is a built up roof, and how does it perform in Tennessee’s unique climate? This post explores the key features of BURs, their benefits, and potential drawbacks, helping property owners make informed decisions.
What Is a Built Up Roof?
A built up roof consists of multiple layers of roofing felt or fabric, alternated with layers of hot-applied asphalt or tar. These layers create a thick, durable membrane that protects the building from water infiltration. The top layer is usually covered with gravel or mineral granules, which shield the asphalt from UV rays and physical damage.
This roofing system is often called a “tar and gravel roof” because of its distinctive finish. BURs are designed primarily for flat or low slope roofs, where water drainage is slower and roofing materials need to be especially water-resistant.
Why Choose a Built Up Roof for Low Slope Roofs in Tennessee?
Tennessee’s climate features hot summers, humid conditions, and occasional severe storms. Low slope roofs in this region face challenges such as standing water, heat buildup, and weather-related wear. Built up roofs offer specific advantages that address these issues:
Water Resistance
The multiple layers of asphalt and felt create a strong barrier against water penetration. This is crucial for low slope roofs where water does not drain quickly.
Durability
BURs can last 20 to 30 years or more with proper maintenance. The gravel layer protects the roof from UV damage and physical wear, extending its lifespan.
Thermal Performance
The thick layers provide some insulation, helping to moderate indoor temperatures during hot Tennessee summers.
Fire Resistance
Asphalt and gravel surfaces offer good fire resistance, an important safety feature in areas prone to wildfires or lightning strikes.
Advantages of Built Up Roofs on Low Slope Roofs in Tennessee
1. Proven Longevity
Built up roofs have a long track record of performance. Many BURs installed decades ago are still functional today. This longevity makes them a cost-effective choice over time, especially when paired with regular inspections and repairs.
2. Strong Protection Against Water Damage
Low slope roofs are vulnerable to leaks because water can pool and seep through weak spots. The multiple layers in BURs reduce the risk of leaks by providing redundancy. Even if one layer is compromised, others remain intact.
3. Resistance to Weather Extremes
Tennessee experiences a range of weather, from heavy rain to intense sun. The gravel surface on BURs protects the asphalt from cracking due to UV exposure and helps prevent damage from hail or debris.
4. Low Maintenance Requirements
While no roof is maintenance-free, built up roofs require less frequent repairs compared to some other low slope options. Routine cleaning of debris and annual inspections usually suffice to keep the roof in good shape.
Disadvantages of Built Up Roofs on Low Slope Roofs in Tennessee
1. Heavy Weight
Built up roofs are heavier than many modern roofing materials. This means the building’s structure must be able to support the added weight. For older buildings or those not designed for heavy roofing, this can be a limiting factor.
2. Installation Complexity and Time
Installing a BUR involves multiple layers and hot asphalt application, which requires skilled labor and safety precautions. The process takes longer than simpler roofing systems, potentially increasing labor costs.
3. Limited Energy Efficiency
While BURs provide some insulation, they are not as energy-efficient as newer roofing materials with reflective coatings or integrated insulation. This can lead to higher cooling costs during Tennessee’s hot summers.
4. Potential for Cracking and Blistering
If not installed or maintained properly, built up roofs can develop cracks or blisters. These defects allow water to penetrate and cause damage. Regular inspections are necessary to catch and repair issues early.
Practical Tips for Tennessee Property Owners Considering BURs
Assess Structural Support
Before choosing a built up roof, have a professional evaluate whether your building can handle the weight.
Hire Experienced Contractors
Proper installation is critical. Look for roofing contractors with proven experience in BUR systems.
Schedule Regular Maintenance
Annual roof inspections and cleaning can prevent minor problems from becoming costly repairs.
Consider Additional Insulation
To improve energy efficiency, add insulation beneath the BUR or explore reflective coatings compatible with built up roofs.
Plan for Weather Events
Ensure your roof has adequate drainage and is inspected after storms to maintain its integrity.
How Built Up Roofs Compare to Other Low Slope Options in Tennessee
Other common low slope roofing options include single-ply membranes like TPO or EPDM, and modified bitumen roofs. Compared to these:
BURs offer superior durability and water resistance but are heavier and more labor-intensive to install.
Single-ply membranes are lighter and often more energy-efficient but may require more frequent maintenance.
Modified bitumen roofs share some similarities with BURs but use factory-made sheets that can be easier to install.
Choosing the right system depends on your building’s structure, budget, and long-term goals.
Built up roofs remain a solid choice for low slope roofs in Tennessee due to their durability and water resistance. While they require careful installation and some maintenance, their long lifespan and protection against the region’s weather make them a practical option. Property owners should weigh the benefits against the weight and installation demands, and consult roofing professionals to select the best system for their needs.
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