Built-Up Roofing: A Reliable and Long-Lasting Flat Roof Solution

Built-up roofing (BUR) has been a trusted choice for commercial and industrial buildings for over a century. Its multi-layered construction offers durability, weather resistance, and energy efficiency, making it one of the most reliable roofing systems available.

What Is a Built-Up Roofing System

A built-up roof consists of multiple layers of bitumen and reinforcing fabrics that are bonded together to create a strong, watertight membrane. It is often finished with a top layer of gravel, mineral granules, or a reflective coating to enhance durability and weather resistance.

Commonly known as tar and gravel roofing, BUR is particularly suited for flat and low-slope roofs. Its layered composition makes it highly resilient against water penetration and environmental damage.

Key Components of Built-Up Roofing

Bitumen Layers

Bitumen acts as the waterproofing agent in a BUR system. It can be applied using:

• Hot asphalt (hot-mopped) – Traditional method using heated bitumen

• Cold-applied adhesives – Safer alternative without the need for high temperatures

• Torch-applied bitumen – Used for enhanced adhesion and durability

Reinforcing Fabrics

These layers provide additional strength and flexibility to the roofing system. The most common materials include:

• Fiberglass mats – Improve fire resistance and stability

• Organic felts – Enhance moisture protection

• Polyester fabrics – Provide flexibility and tensile strength

Surfacing Materials

The top layer of a BUR system protects the roof from environmental damage. Common surfacing options include:

• Gravel or crushed stone – Provides UV protection and impact resistance

• Reflective coatings – Reduces heat absorption and improves energy efficiency

• Cap sheets – Granulated surfaces that enhance waterproofing properties

Benefits of Built-Up Roofing

Long Lifespan

With proper installation and maintenance, a BUR system last 30 to 40 years, making it one of the longest-lasting flat roofing options available.

Superior Waterproofing

The multiple layers create a seamless and watertight barrier, significantly reducing the risk of leaks and water damage.

Fire and Weather Resistance

BUR systems have high fire ratings, making them a safer choice for commercial buildings. The gravel or mineral surface acts as a fire-resistant shield, preventing flame spread. Additionally, the multi-layered structure provides excellent protection against wind, rain, and extreme temperatures.

Energy Efficiency

Reflective coatings or light-colored surfacing materials can reduce heat absorption, helping lower cooling costs. The insulation within a BUR system also contributes to improved energy efficiency.

Low Maintenance Requirements

BUR systems require minimal maintenance, with routine inspections and occasional resurfacing to extend their lifespan. Their durable composition makes them resistant to punctures and minor damage.

Common Issues with Built-Up Roofing

Ponding Water

Flat roofs often experience water pooling in low areas, which can lead to premature deterioration if not addressed. Proper drainage solutions such as tapered insulation, scuppers, or internal drains can prevent this issue.

Blistering and Cracking

Over time, trapped moisture or air pockets between layers may cause blisters or cracking. These issues can be mitigated through regular inspections and timely repairs.

Flashing Failures

Flashings are crucial for sealing roof penetrations, such as vents and chimneys. Poorly installed or deteriorated flashings can result in leaks and water damage. Replacing damaged flashings

promptly ensures the roof remains watertight.

Built-Up Roofing vs. Other Flat Roofing Systems

Feature	Built-Up Roofing (BUR)	Single-Ply Roofing (TPO, EPDM)	Modified Bitumen
Lifespan	30-40 years	20-30 years	20-30 years
Waterproofing	Excellent	Moderate	High
Fire Resistance	High	Moderate	High
Energy Efficiency	High (with coatings)	High (reflective options available)	Moderate
Installation Time	Longer	Faster	Moderate
Cost	Moderate to High	Moderate	Moderate

How to Maintain a Built-Up Roof

Regular Inspections

Conduct inspections twice a year (spring and fall) and after major storms to identify potential issues such as cracks, blisters, or pooling water.

Clearing Debris

Removing leaves, branches, and other debris from the surface and drainage system helps prevent moisture buildup and extends the roof’s lifespan.

Applying Roof Coatings

Reflective or waterproof coatings can enhance UV resistance, waterproofing, and energy efficiency. These coatings should be reapplied every 5 to 10 years depending on climate conditions.

Timely Repairs

Addressing small issues promptly can prevent costly damage. Minor blisters or cracks can be repaired with patching materials and sealants before they escalate.

Professional Built-Up Roof Installation and Repair

For a BUR system to achieve maximum longevity and performance, expert installation and maintenance are essential. Property owners seeking high-quality commercial roofing services can rely on East Penn Roofing, located in Lehigh Valley, PA. The company is recognized for its superior craftsmanship and holds industry-leading certifications, including:

• OSHA Safety Certified

• Atlas Pro Certified

• Owens Corning Preferred Contractor

• CertainTeed Shingle Select Contractor

• Roofing Insights Preferred Contractor

• GAF Certified Installer

• Velux 5-Star Certified Contractor

• SRCA Slate Roofing

• HAAG Certified

Frequently Asked Questions

How long does a built-up roof last

With proper maintenance, a BUR system can last 30 to 40 years, making it one of the most durable flat roofing options available.

What is the main advantage of a built-up roof

The multi-layered structure provides exceptional waterproofing, fire resistance, and longevity, making it ideal for commercial and industrial buildings.

Can a built-up roof be repaired

Yes, minor issues such as cracks, blisters, and flashing failures can be repaired without requiring a full replacement. Regular maintenance helps prevent major damage.

Is a built-up roof energy-efficient

Yes, especially when coated with reflective materials that reduce heat absorption, leading to lower cooling costs.

How much does a built-up roof cost

The cost varies based on materials and labor but typically ranges between 5 to 12 dollars per square foot, making it a cost-effective long-term solution.

Conclusion

Built-up roofing remains a top choice for flat roofs due to its durability, fire resistance, and superior waterproofing. With proper installation and routine maintenance, a BUR system can provide decades of reliable performance. Property owners looking for a long-lasting, low-maintenance roofing solution should consider built-up roofing for their next project.

Read also our blog: Metal Roofing: A Durable and Stylish Roofing Solution