Built Up Roof

When it comes to roofing solutions, a built-up roof (BUR) stands out for its durability and versatility. This traditional method, often seen on commercial buildings, consists of multiple layers of roofing felt and asphalt, creating a robust barrier against the elements. If you're considering a roofing upgrade or installation, understanding the benefits of BUR can help you make an informed decision.

Cost is a crucial factor in any roofing project. While the initial investment for a built-up roof can range from $5 to $10 per square foot, its longevity and low maintenance needs often make it a cost-effective choice over time. With proper installation and care, a BUR can last 20 years or more, providing excellent value for your investment.

What Is a Built Up Roof?

A Built Up Roof (BUR) is a reliable roofing system designed for low-slope or flat roofs. This method consists of multiple layers of materials, creating a solid, continuous roof membrane.

Composition of Built Up Roofs

A typical BUR consists of several essential components:

• Base Sheet: The first layer applied directly to the roof deck. It often gets nailed or fully adhered, establishing the initial waterproof barrier and serving as the foundation for the BUR system. Base sheets can comprise fiberglass and frequently get saturated with asphalt for enhanced strength and water resistance.
• Felts: Layers of roofing felt, made from organic or fiberglass materials, are applied over the base sheet. These layers add durability and insulation while increasing the roof's overall waterproofing capabilities.
• Asphalt: Hot or cold asphalt serves as the adhesive between layers. This substance is integral for creating a strong, weather-resistant bond among the textured components.
• Surface Layer: The final layer. This can be gravel, stone, or a reflective coating that provides additional protection against UV rays and physical damage.

Types of Built Up Roof Systems

Various BUR systems cater to different needs and preferences:

• Traditional Built Up Roofs: Multiple layers of roofing felt embedded in asphalt, providing robust waterproofing and durability.
• Modified Bitumen Roofs: A modern variant that involves pre-manufactured sheets fused together to create a seamless surface. This option offers enhanced flexibility and ease of installation.
• Cold Processed Roofs: Utilizes a cold adhesive to bond layers without the need for heat. This system is safer and easier to install in certain environments.

Each type offers unique advantages, enabling you to choose the best fit for your project's specific requirements.

Advantages of Built Up Roofs

Built-Up Roofs (BUR) offer numerous benefits, especially in terms of durability, longevity, and cost-effectiveness. These roofs can provide reliable protection for your building for many years.

Durability and Longevity

BUR systems feature multi-layered construction, utilizing multiple layers of bitumen, either asphalt or coal tar, combined with reinforcing fabrics. This robust design safeguards against water, wind, and various weather conditions. If one layer experiences damage, the underlying layers maintain protection. BUR roofs boast an impressive lifespan, typically lasting 20 to 30 years, with some instances reaching up to 40 years or more under ideal conditions. Each layer of bitumen contributes approximately five additional years to the roof's overall lifespan. Additionally, the gravel or aggregate top layer enhances impact resistance, defending against hail, storm debris, and foot traffic.

Cost-Effectiveness

Although the initial investment for BUR ranges from $5 to $10 per square foot, the long-term savings can be significant. You'll find that BUR offers a low maintenance requirement, allowing you to minimize ongoing costs. Given the lifespan and durability, BUR systems often prove to be a cost-effective roofing solution, balancing upfront expenses with extended value over time.

Installation Process of Built Up Roofs

The installation process of Built-Up Roofs (BURs) involves systematic preparation and the appropriate selection of materials, followed by a clear step-by-step approach. This ensures effective application and long-lasting performance.

Preparation and Materials

• Surface Preparation: Start by inspecting the roof deck. Ensure the surface is clean, dry, and structurally sound. Remove debris, old roofing materials, and any imperfections. This step ensures proper adhesion of the bitumen layers.
• Materials:
• Base Sheet: Apply the first layer, often made from fiberglass and saturated with asphalt. This layer provides strength and water resistance.
• Bitumen: Use asphalt or coal tar as the primary waterproofing material. Asphalt is popular for its weathering characteristics, while coal tar offers enhanced water resistance and self-healing properties.
• Reinforcing Fabrics: Embed layers of roofing felt or fiberglass mats between bitumen layers. This process strengthens and stabilizes the roofing system.

1. Inspect the Roof Deck: Evaluate the condition of the roof deck for clean and sound surfaces.
2. Apply the Base Sheet: Lay down the base sheet securely to form the foundation of the BUR system.
3. Install Bitumen Layers: Heat and apply the first layer of bitumen evenly over the base sheet. Use a torch or hot asphalt application, ensuring seamless coverage.
4. Add Reinforcing Fabrics: Embed reinforcing fabrics into the heated bitumen layer. This adds structural integrity to the roofing system.
5. Repeat Bitumen and Fabric Layers: Alternate between layers of bitumen and fabrics to build the desired thickness and strength. Each layer should overlap the previous one to prevent water infiltration.
6. Finish with a Top Layer: Apply a final layer of bitumen and then coat with gravel or aggregates. This layer protects against UV rays and provides additional impact resistance.

By following these steps, you can achieve a durable, effective Built-Up Roof system that ensures long-term performance against various weather conditions.

Maintenance and Repair of Built Up Roofs

Regular maintenance ensures the longevity and performance of Built-Up Roofs (BURs). Routine inspections and timely repairs prevent minor issues from escalating into costly problems.

Regular Maintenance Practices

To extend the life of a BUR, implement these key practices:

• Inspect the Roof Regularly: Check for signs of damage like cracks, blisters, ridges, and wrinkles. Mark areas needing attention with roofer’s chalk.
• Clean the Roof: Sweep away loose aggregate, dirt, and silt using a stiff-bristled brush or broom. Focus on embedded aggregate, and ensure parapets, copings, and flashings are clean.
• Check for Bald Spots: Identify and replenish areas where gravel or aggregate is missing to maintain effective UV protection and waterproofing.
• Address Efflorescence: Remove efflorescence from brickwork using stiff, non-metallic bristle brushes to prevent moisture issues.

Common Repair Techniques

When addressing issues with BURs, consider these common methods:

• Fix Cracks and Blisters: Apply a patch of roofing fabric combined with asphalt or bitumen over the damaged area. Ensure the patch extends past the repair to create a strong seal.
• Replenish Aggregate: For bald spots, add a layer of gravel or aggregate as necessary. This helps enhance weather resistance and protect the underlying layers.
• Repair Flashings: Inspect and replace damaged or loose flashings. Secure new flashings with appropriate adhesives or mechanical fasteners to ensure a watertight seal.
• Resurface the Roof: For extensive wear, consider resurfacing with a layer of modified bitumen or elastomeric coating. This approach rejuvenates the roof surface and adds an additional layer of protection.

Conclusion

Choosing a built-up roof (BUR) can be a smart investment for your commercial property. Its multi-layered design not only provides exceptional durability but also ensures long-lasting protection against harsh weather conditions. With proper installation and regular maintenance, you can maximize the lifespan of your BUR, potentially saving you money in the long run.

This roofing solution offers flexibility with various types available to suit your specific needs. Whether you opt for traditional BURs or modified bitumen roofs, you're making a choice that prioritizes both reliability and performance. By understanding the advantages and maintenance requirements, you can confidently select a BUR that meets your expectations and keeps your building safe for years to come.

Frequently Asked Questions

What is built-up roofing (BUR)?

Built-up roofing (BUR) is a roofing system designed for low-slope or flat roofs, composed of multiple layers of roofing felt and asphalt. This multi-layered construction creates a solid, continuous membrane that provides strong protection against water, wind, and weather elements.

How long does a BUR last?

A built-up roof typically has a lifespan of 20 to 30 years, but with proper maintenance, it can last up to 40 years. Each added layer of bitumen extends the roof's longevity by approximately five years.

What are the cost considerations for BUR?

The initial cost for installing a BUR ranges from $5 to $10 per square foot. However, due to its low maintenance requirements and durability, BUR can be a cost-effective solution over time, leading to long-term savings.

What are the advantages of built-up roofing?

BUR offers numerous advantages, including exceptional durability, longevity, weather resistance, and low maintenance needs. Its multi-layered structure protects against various elements and enhances impact resistance, making it ideal for commercial buildings.

How is a BUR installed?

The installation of a BUR involves several steps: preparing the roof surface, applying a base sheet, layering bitumen with reinforcing fabrics, and finishing with a top layer of bitumen and gravel. Each stage is crucial for creating a durable roof.

What maintenance does a BUR require?

Regular maintenance for BURs includes inspections for damage, cleaning the surface, and checking for bald spots. Addressing issues like cracks and blisters promptly helps prevent minor problems from becoming costly repairs, ensuring longevity.

What types of BUR systems are available?

There are several types of BUR systems, including traditional BURs, modified bitumen roofs, and cold processed roofs. Each type has distinct advantages tailored to meet specific project requirements and environmental conditions.