BUILT UP ROOF

Built-Up Roof (BUR) Overview

 

A built-up roof (BUR) is a traditional and widely used roofing system characterized by its layered construction, which provides exceptional durability and waterproofing for flat or low-slope applications. This roofing system has been a staple in commercial and industrial buildings due to its longevity and reliability, making it an essential component of modern architecture.

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Composition and Structure

A typical built-up roof consists of multiple layers of roofing felt or fabric, usually made from fiberglass or organic materials, that are adhered together using asphalt or bitumen. The structure usually includes the following components:

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1. Decking: The base layer, often made from plywood, concrete, or metal, serves as the foundation for the roofing system.

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2. Insulation: A layer of insulation may be added to enhance energy efficiency, typically using rigid foam or other insulating materials.

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3. Roofing Felt: Several layers of roofing felt are installed over the insulation, providing additional waterproofing. These felts are often saturated with asphalt.

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4. Bitumen: Hot or cold asphalt is applied to bond the layers together. Hot asphalt is typically applied when the roofing system is installed, while cold asphalt can be used for maintenance and repairs.

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5. Surface Layer: The top layer may consist of a protective coating, gravel, or other materials to provide UV resistance and further protect the underlying layers from weather and physical damage.

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Installation Process

The installation of a built-up roof requires skilled labor and attention to detail. Here’s a brief overview of the typical installation process:

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1. Preparation: The roof deck is inspected for any damage or irregularities. Repairs are made as necessary to ensure a solid base.

2. Insulation Installation: If insulation is required, it is installed over the deck. This can help improve energy efficiency and reduce heating and cooling costs.

3. Layering: Roofing felt is applied in layers, typically consisting of three to five layers, with bitumen applied between each layer to adhere them securely.

4. Surface Treatment: A final layer of gravel or a protective coating is added to shield the roofing materials from UV rays, extreme temperatures, and physical wear.

5. Inspection: Once installation is complete, the roof is thoroughly inspected to ensure there are no weak points or potential leaks.

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Advantages of Built-Up Roofs

1. Durability: Built-up roofs are known for their long lifespan, often lasting 20-30 years or more with proper maintenance. The multiple layers provide robust protection against weather conditions, including heavy rain, snow, and UV radiation.

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2. Waterproofing: The layered design ensures excellent waterproofing, reducing the risk of leaks and water damage.

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3. Customizability: BUR systems can be tailored to meet specific building needs, including varying thicknesses and materials based on environmental conditions and desired performance.

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4. Energy Efficiency: When insulation is incorporated, built-up roofs can improve energy efficiency by reducing heat loss in colder months and keeping buildings cooler in warmer weather.

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5. Low Maintenance: Once installed, BUR systems require minimal maintenance, primarily involving periodic inspections and surface cleaning to remove debris.

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Disadvantages of Built-Up Roofs

1. Weight: The multiple layers of roofing materials can make BUR systems quite heavy, which may require additional structural support in some buildings.

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2. Installation Complexity: The installation process can be labor-intensive and time-consuming, often requiring professional expertise.

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3. Potential for Blistering: Improper installation or inadequate ventilation can lead to blistering, where air pockets form within the layers, potentially compromising the roof's integrity.

4. Heat Sensitivity: The asphalt used in BUR systems can become soft in extreme heat, which may lead to deformation or other issues if not properly managed.

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Maintenance of Built-Up Roofs

Regular maintenance is crucial for extending the lifespan of a built-up roof. Key maintenance practices include:

 

1. Routine Inspections: Conducting regular inspections at least twice a year, as well as after severe weather events, helps identify potential issues before they escalate.

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2. Debris Removal: Keeping the roof clear of debris, such as leaves, branches, and dirt, is essential for preventing water pooling and promoting proper drainage.

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3. Repairing Damages: Promptly addressing any signs of damage, such as cracks, blisters, or punctures, can prevent further deterioration and extend the roof's lifespan.

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4. Cleaning Gutters and Drains: Ensuring that gutters and drainage systems are clear and functioning correctly is critical for preventing water backup and potential leaks.

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5. Re-coating: Applying a reflective coating can help protect the surface from UV rays and improve energy efficiency.

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Environmental Considerations

Built-up roofs can be designed with environmental sustainability in mind. Options such as reflective coatings can enhance energy efficiency, while materials can be selected for their low environmental impact. Additionally, the use of recycled materials in the roofing system contributes to sustainable building practices.

 

In summary, a built-up roof is a versatile and resilient roofing system that has stood the test of time. Its layered construction provides exceptional waterproofing and durability, making it an ideal choice for flat and low-slope roofs in commercial and industrial applications. While it requires professional installation and regular maintenance, the long-term benefits, including energy efficiency and longevity, make it a worthwhile investment for building owners seeking reliable roofing solutions. Whether you're considering a new roofing system or maintaining an existing one, understanding the intricacies of built-up roofs can help you make informed decisions that protect your building and enhance its overall performance.