Built-Up Roofing Systems Explained
Last Updated on 12/16/2023 by Matteo Lombardo
Built-Up Roofing Systems are a strong choice for many buildings. They have layers that work together to last a long time. Our guide explains how these roofs work and why they are so reliable.
Key Takeaways
| Section | Key Points |
|---|---|
| What is a Built-Up Roof? | – Multi-layered roofing system for flat roofs – Layers include base sheets, felt, and surfacing – Popular for durability and cost-effectiveness |
| What’s The Lifespan? | – Lasts 15-30 years – Influenced by installation quality, climate, maintenance, and design |
| Parts of a BUR System | – Includes roof deck, vapor retarder, insulation, base sheets, interply sheets, felt, surfacing, and flashings |
| Benefits of Built-Up Roofing | – Durable, excellent waterproofing, long lifespan, cost-effective, fire-resistant, UV protection |
| Disadvantages of Built-Up Roofs | – Heavy weight, absorbs heat, complex installation, maintenance needs, limited aesthetic options |
| Built-Up Roofing Average Cost | – $2.75 – $6 per sq. ft. – Varies with layers, local market, and project specifics |
| 3 Ply Built-Up Roofing | – Uses three layers of felt – Balances protection, durability, and cost – Suitable for various climates and buildings |
| Final Thoughts on Built-Up Roofing | – Reliable and versatile choice – Suitable for commercial buildings – Consider weight, installation, and climate |
What is a Built-Up Roof?
What is a Built-Up Roof? Built-up roofing, often called BUR, is a popular roofing system for flat or nearly flat roofs. It’s been used for over 100 years, making it a time-tested option.
BUR is made by layering several sheets of roofing materials, creating a thick, durable surface. It’s like making a sandwich, with each layer adding strength and protection.
📌 More about this service: Built-Up Roofing Systems in Framingham, MA
Why is it Called “Built-Up”?
The term “Built-Up” comes from how the roof is made. It’s built up, layer by layer, right on the roof. Each layer plays a role in protecting the building. Think of it like adding layers to a winter outfit; each one adds warmth and protection.
Application
How is a Bult-Up Roof Applied? BUR is applied right on the roof. Professionals heat the asphalt, making it like a thick liquid. They then mop it over the base sheets, add the felt layers, and mop more asphalt. The process is repeated until the right thickness is reached. Then, they add the final surfacing.
Who Uses Built-Up Roofs?
BUR is mainly used on commercial buildings, but it’s also seen on residential flat roofs. Its durability and cost-effectiveness make it a good choice for large roofs, where other materials might be too expensive or impractical.
The Layers of a BUR
There are typically three to five layers in a BUR system:
- Base Sheets: The first layers are attached to the roof deck.
- Interply Sheets: These add strength to the top of the base sheets.
- Felt Layers: Soaked-in asphalt makes the roof waterproof.
- Flood Coat: This is the top layer of asphalt, sealing everything.
- Surfacing: This final layer can be gravel, mineral granules, or a smooth coating. It protects against the sun and weather.
What’s The Lifespan of a Built-Up Roof?
A well-installed and properly maintained BUR lasts 20 to 30 years. A BUR system’s lifespan depends on the installation’s quality, the number of layers, and the regularity of maintenance and inspections.
Factors Influencing Lifespan
Several factors can affect how long a BUR system will last:
- Quality of Installation: The skill and experience of the roofing professionals play a big role. A well-installed roof lasts longer.
- Climate: Areas with extreme weather, like heavy rain, snow, or high temperatures, can reduce a roof’s lifespan.
- Maintenance: Regular inspections and repairs can significantly extend a roof’s life.
- Foot Traffic: If people frequently walk on the roof, it can wear out faster.
- Roof Design: The slope and design of the roof can affect drainage and overall durability.
Maintenance is Key
To get the most out of a BUR, regular maintenance is essential. This includes:
- Inspections: Ideally, twice a year, after major weather events.
- Cleaning: Removing debris and keeping drains clear.
- Repairs: Fixing any damage or wear quickly to prevent bigger issues.
Comparison with Other Roofing Types
Compared to other roofing types, such as shingle or metal roofs, BUR’s lifespan falls in a comfortable middle ground. While some materials might last longer, they often come with a higher cost. BUR offers a balance of durability and affordability.
Elements of a BUR System
Understanding the parts of a Built-Up Roofing (BUR) system is key to appreciating how it provides reliable building protection.
Each component of a BUR plays a crucial role in its overall performance and durability. Here’s a breakdown of the typical parts of a BUR system:
1. Roof Deck
- This is the foundation of the roofing system, usually made of concrete, metal, or wood.
- It supports all the layers of the BUR.
2. Vapor Retarder
- This layer, sometimes optional, is placed directly on the roof deck.
- It prevents moisture inside the building from getting into the roof system.
3. Insulation
- This layer varies in material, including foam, fiberglass, or other insulating materials.
- It helps control the building’s temperature and adds to the roof’s structural integrity.
4. Base Sheets
- These are the first layers of the actual roofing material, often made of fiberglass or organic mats.
- They form a solid base for the layers above.
5. Interply Sheets
- Similar to base sheets, these are additional layers added for strength.
- They increase durability and are essential for the waterproofing process.
6. Roofing Felt
- These are sheets soaked in asphalt, coal tar, or cold-applied adhesive.
- They are the main waterproofing elements of the BUR.
7. Surfacing Material
- This is the top layer: gravel, mineral granules, a liquid coating, or reflective coatings.
- It protects against UV rays, weather, and mechanical damage.
8. Flashings
- These are materials used around the edges of the roof, walls, and other interruptions.
- They ensure that these vulnerable points are well-protected against leaks.
Each part of a Built-Up Roofing system plays a specific and crucial role. From the foundational roof deck to the protective surfacing material, every layer contributes to the system’s overall durability, stability, and ability to keep a building safe and dry.
Elements of a BUR System
Understanding the parts of a Built-Up Roofing (BUR) system is key to appreciating how it provides reliable building protection. Each component of a BUR plays a crucial role in its overall performance and durability. Here’s a breakdown of the typical parts of a BUR system:
1. Roof Deck
- This is the foundation of the roofing system, usually made of concrete, metal, or wood.
- It supports all the layers of the BUR.
2. Vapor Retarder
- This layer, sometimes optional, is placed directly on the roof deck.
- It prevents moisture inside the building from getting into the roof system.
3. Insulation
- This layer varies in material, including foam, fiberglass, or other insulating materials.
- It helps control the building’s temperature and adds to the roof’s structural integrity.
4. Base Sheets
- These are the first layers of the actual roofing material, often made of fiberglass or organic mats.
- They form a solid base for the layers above.
5. Interply Sheets
- Similar to base sheets, these are additional layers added for strength.
- They increase durability and are essential for the waterproofing process.
6. Roofing Felt
- These are sheets soaked in asphalt, coal tar, or cold-applied adhesive.
- They are the main waterproofing elements of the BUR.
7. Surfacing Material
- This is the top layer: gravel, mineral granules, a liquid coating, or reflective coatings.
- It protects against UV rays, weather, and mechanical damage.
8. Flashings
- These are materials used around the edges of the roof, walls, and other interruptions.
- They ensure that these vulnerable points are well-protected against leaks.
Each part of a Built-Up Roofing system plays a specific and crucial role. From the foundational roof deck to the protective surfacing material, every layer contributes to the system’s overall durability, stability, and ability to keep a building safe and dry.
Benefits and Disadvantages of Built-Up Roofing Systems
When considering a Built-Up Roofing (BUR) system, weighing its advantages and disadvantages is important. This balanced view helps in making an informed decision.
Below is a table summarizing the key benefits and disadvantages of BUR:
| Advantages | Disadvantages |
|---|---|
| 1. Durability | 1. Weight |
| BUR is known for its toughness and ability to withstand heavy foot traffic and environmental factors. | BUR systems are heavy, which might require additional structural support for the building. |
| 2. Waterproofing | 2. Heat Absorption |
| The multiple layers and tight seal offer excellent waterproofing, reducing the risk of leaks. | BUR can absorb a lot of heat, especially if not coated with reflective materials, leading to higher cooling costs. |
| 3. Long Lifespan | 3. Installation Complexity |
| With proper maintenance, BUR can last 15 to 30 years, making it a long-term roofing solution. | The installation process is complex and requires skilled professionals, which can add to the overall cost. |
| 4. Cost-Effective Over Time | 4. Maintenance Requirements |
| Though the initial cost may be high, the long lifespan and durability make it cost-effective in the long run. | Regular maintenance is necessary to ensure the roof’s longevity, which can be a drawback for some. |
| 5. Fire Resistance | 5. Limited Aesthetic Options |
| BUR materials are generally fire-resistant, adding an extra layer of safety to the building. | Compared to other roofing types, BUR offers fewer aesthetic options. |
| 6. UV Protection | 6. Installation Weather Limitations |
| The top layer can be treated to offer UV protection, helping to control building temperatures. | The installation of BUR is weather-dependent, often requiring dry conditions, which can delay projects. |
Built-up roofing systems offer a range of benefits like durability, excellent waterproofing, and fire resistance, making them a solid choice for many buildings.
Considerations like weight, heat absorption, and maintenance needs are essential. This comprehensive view helps you understand whether a BUR system is the right fit for your roofing needs.
Built-Up Roofing Average Cost
When planning for a new roof, understanding the costs involved is crucial. The average cost of Built-Up Roofing (BUR) varies based on several factors.
Here’s a detailed look at what you can expect to pay for a BUR system:
| Cost Component | Cost Range | Details |
|---|---|---|
| Material Cost | $0.75 – $2 per sq. ft. | This includes the base sheets, interply sheets, and surfacing materials. The price varies based on the quality and type of materials used. |
| Installation & Labor | $2 – $3 per sq. ft. | Labor costs depend on the complexity of the installation, the contractor’s experience, and local labor rates. |
| Total Cost | $2.75 – $6 per sq. ft. | This is the combined cost for materials and labor for a standard BUR installation. |
Additional Considerations
- Number of Layers: More layers increase material and labor costs.
- Local Market: Prices can vary based on the region due to labor costs and material availability differences.
- Project Specifics: A project’s Unique requirements, like the roof’s design and accessibility, can affect the overall cost.
Comparison with Other Estimates
Another estimate suggests that the basic cost to install BUR could be higher, ranging from $7.46 to $9.22 per square foot. This discrepancy highlights the importance of considering various factors influencing the final cost.
Customized Estimates
For an accurate assessment, getting a customized estimate based on your specific location, roof size, and project options is essential. Each project is unique, and costs can vary significantly.
3 Ply Built-Up Roofing
What is 3 Ply Built-Up Roofing? 3 Ply Built-Up Roofing (BUR) is a specific type of BUR system characterized by the use of three layers (or “plies“) of roofing felt, each embedded in bitumen.
This setup is designed to balance protection, durability, and cost-effectiveness. Let’s delve into the specifics of 3 Ply BUR:
Composition of 3-Ply BUR
- Base Layer: Attached directly to the roof deck, this layer forms the foundation.
- Ply Layers: Three layers of roofing felt, each embedded in hot bitumen (asphalt or tar). These layers are the core of the 3-ply system, providing the main waterproofing barrier.
- Top Layer: The final surfacing, often gravel or a smooth coating, protects against UV rays and physical damage.
Benefits of 3 Ply BUR
- Enhanced Durability: The three layers of felt offer greater strength and longevity compared to single-ply systems.
- Improved Waterproofing: Multiple layers ensure better water resistance.
- Cost-Effective: It’s more affordable than systems with more layers while providing robust protection.
- Adaptability: Suitable for various climates and building types.
Considerations for 3 Ply BUR
- Weight: It’s lighter than systems with more layers but still heavier than single-ply options.
- Installation: Requires professional installation due to the complexity of working with hot bitumen.
- Maintenance: Regular inspections and maintenance are necessary to ensure longevity.
Ideal Use Cases
3 Ply BUR is ideal for:
- Buildings with flat or low-slope roofs.
- Projects where a balance between cost and durability is desired.
- Environments where moderate to heavy rainfall is expected.
3 Ply Built-Up Roofing is a middle-ground option in the BUR family. It offers improved durability and waterproofing compared to single-ply systems but is more cost-effective than systems with more layers.
Its suitability for various climates and building types makes it popular for many commercial and residential applications.
Final Thoughts on Built-Up Roofing
As we wrap up our exploration of Built-Up Roofing (BUR) systems, it’s clear that this roofing option has stood the test of time for good reasons.
BUR offers a reliable, durable, and versatile solution for flat or low-slope roofs, particularly in commercial settings. Here are some key takeaways:
Why Choose BUR?
- Durability: BUR’s multiple layers protect against weather and wear.
- Waterproofing: The tight seal of BUR systems makes them highly resistant to water leaks.
- Longevity: A BUR system can last up to 30 years with proper maintenance.
- Fire Resistance: Most BUR materials are fire-resistant, adding an extra layer of safety.
- Cost-Effectiveness: Though the initial investment can be significant, the long lifespan and low maintenance costs make BUR a financially sound choice in the long run.
Considerations Before Installation
- Weight: Ensure your building can support the weight of a BUR system.
- Professional Installation: Choose experienced contractors for a quality installation.
- Climate Suitability: Consider how the local climate might affect the performance of a BUR roof.
The Future of BUR
Advancements in roofing materials and techniques continue to enhance the appeal of BUR. Innovations like improved bitumen formulas and eco-friendly options make BUR more resilient and sustainable.
Final Advice
If you’re considering a BUR system for your building, it’s important to consult with roofing professionals. They can provide tailored advice and help you navigate the specifics of your project.
Remember, a well-informed decision is key to getting a roofing solution that meets your needs, budget, and expectations.
