Multi-layer Asphalt with Gravel
Asphalt and gravel built-up roofs (BUR) are known for their strength and excellent waterproofing, providing optimal protection against harsh weather conditions. The final layer of gravel shields the surface from UV rays and reduces heat absorption, improving energy efficiency.
This guide explores why this roofing system is a reliable choice for both industrial buildings and residential properties.
What Is Asphalt and Gravel Built-Up Roofing?
BUR is a multi-layer roofing system designed for flat roofs. Its principle is based on applying multiple layers of asphalt-saturated membranes, which are stacked to create an effective moisture barrier.
How Is It Installed?
- The process begins with 4 to 5 layers of felt paper saturated with asphalt.
- These layers are sealed using hot bitumen to ensure maximum waterproofing.
- Once the base layers are complete, an additional coat of hot asphalt is applied on top.
- Finally, crushed white gravel is spread over the surface for added protection.
Why Is Gravel Used?
- It protects the asphalt membrane from UV rays, preventing premature deterioration.
- It enhances the roof’s lifespan, maintaining its durability for approximately 16 years.
While asphalt-based BUR systems are not as long-lasting as coal tar-based options, they still provide strong waterproofing and mechanical resistance, making them an effective choice for preventing leaks and water infiltration.
This roofing system is commonly used in commercial and residential buildings, but regular inspections are essential since extreme weather conditions can affect its integrity.
Advantages and Disadvantages of Built-Up Roofing (BUR)
1. Cost-Effective Roofing Solution
Built-up roofing is relatively affordable compared to other roofing systems, making it a cost-efficient option for large surfaces.
2. Superior Weather Resistance
- The multi-layer design provides excellent waterproofing, even under extreme weather conditions.
- It withstands heavy rain, snowfall, strong winds, and hailstorms, ensuring long-term durability.
3. Long-Lasting and Repairable
- The lifespan of asphalt and gravel BUR is typically 10 to 16 years, but proper maintenance can extend its durability.
- Minor repairs, such as reapplying gravel to specific areas, can add extra years to the roof’s longevity.
4. UV Protection
- The crushed gravel layer protects the asphalt membrane from UV exposure, reducing wear and preventing premature damage.
5. Adaptability to Roof Installations
BUR is compatible with various rooftop installations, including:
- Ventilation systems
- Skylights
- Chimneys
- Drainage systems
This flexibility allows for seamless integration of essential rooftop components.
6. Easy Repair Process
BUR does not require specialized skills for maintenance and minor repairs, making it a practical roofing solution.
Potential Drawbacks
Despite its benefits, BUR has some limitations:
- Frequent Maintenance Required
Compared to modern roofing materials like elastomeric membranes, BUR has a shorter lifespan (10–16 years) and requires consistent maintenance. - Heavy Weight
The multiple layers of asphalt and gravel add significant weight, requiring structural reinforcement in some buildings. - Strong Bitumen Odor
The installation process emits strong odors, which can be unpleasant, especially in residential areas. - Weather-Dependent Installation
- Weather conditions affect the quality of installation.
- Cold temperatures and high humidity can compromise the bonding of asphalt layers.
Installation and Maintenance of Asphalt and Gravel BUR
Installation Process
Proper installation is critical for the performance and longevity of a built-up roofing system. The process follows these steps:
- A #15 felt paper layer is spread over the roof surface.
- This felt is saturated with hot asphalt to create the base waterproofing layer.
- A final gravel coating is applied to protect the membrane from UV exposure and extreme weather conditions.
Why Hire a Professional?
- Weather conditions and asphalt temperature directly impact the quality of installation.
- Certified roofing professionals ensure proper application and long-term performance.
Regular Maintenance for Maximum Durability
1. Maintain Gravel Distribution
- Gravel must remain evenly distributed to protect the membrane.
- If gravel shifts or exposes the asphalt, the affected areas must be swept, treated with liquid asphalt, and re-coated with fresh gravel.
2. Schedule Annual Roof Inspections
- Check for bald spots or exposed asphalt layers to prevent premature deterioration.
- Regular maintenance helps detect and repair minor issues before they escalate.
3. Clean Drainage Systems
- Remove debris from drains and gutters to ensure proper water runoff.
- Blocked drainage systems can lead to water accumulation, which accelerates roof damage.
4. Optimize Thermal Performance with White Gravel
Using white-colored gravel provides additional advantages:
- Reflects solar heat, reducing indoor temperatures.
- Enhances energy efficiency by minimizing heat buildup.
Why Choose a Built-Up Roof for Your Project?
A Trusted Choice for Industrial and Residential Buildings
Built-up roofing is a proven solution for flat roofs, offering high durability and strong waterproofing performance.
An Affordable Alternative to Modern Roofing Systems
While newer materials like elastomeric membranes offer longer lifespans, BUR remains a cost-effective option for those seeking a reliable and budget-friendly roofing system.
Built for Harsh Weather Conditions
BUR systems withstand:
- Heavy snowfall
- Intense heat and UV exposure
- Strong winds and storms
Montreal’s Expert Roofing Services
For roofing installation or maintenance, trust our certified roofing professionals.
Our Montreal-based team specializes in:
- High-quality built-up roofing installations
- Reliable repair and maintenance services
- Custom roofing solutions tailored to your project
Looking for a durable, cost-effective roofing system? Contact us today for a free consultation and expert advice!