Area Built Up Roofing (BUR) combines multiple layers of asphalt-saturated felts and protective coatings to form a durable, waterproof membrane for flat and low-slope roofs. This guide explains what BUR roofing is, how it is installed, its benefits and drawbacks, and best practices for maintenance and longevity in the American market. By understanding BUR roofing components, installation methods, and cost considerations, facility owners and builders can evaluate whether Area Built Up Roofing is the right choice for their project.
What Is Built Up Roofing (BUR)?
BUR roofing is a traditional, versatile roofing system that uses alternating layers of bituminous materials and reinforcing felts, topped with a protective surface layer. The phrase “built up” describes how the membrane is assembled in layers, creating a robust, watertight assembly suitable for low-slope roofs in many climates. Modern BUR can incorporate fiberglass or organic felts and may use cold or hot application methods depending on the project requirements and material availability. The finished surface often features gravel, mineral granules, or a reflective coating to protect against UV exposure and weathering.
Key Materials And Components
- Asphalt-Soaked Felt Or Fiberglass Felts: Serve as the core reinforcement, providing strength and barrier properties.
- Bitumen: Typically asphalt or coal tar pitch used as the adhesive and waterproofing layer between plies.
- Insulation And Deck: The BUR system rests on an existing roof deck with insulation layers when required for thermal performance.
- Surface Cap: Gravel, mineral granules, or reflective coatings to shield the membrane and improve longevity.
- Waterproofing Membranes: Some systems incorporate a rubberized asphalt or an elastomeric top coat for enhanced flexibility.
Benefits And Drawbacks
- Durability: Multiple plies offer excellent waterproof protection and resistance to hail and wind uplift when properly installed.
- Cost-Effectiveness: Low material costs per square foot and proven performance for many building types.
- Repairability: Damaged sections can often be repaired without full panel replacement.
- Thermal Performance: Can be customized with reflective coatings to reduce cooling loads in hot climates.
- Maintenance Needs: Requires periodic inspection for blistering, ridging, or gravel loss; neglect can shorten lifespan.
- Environmental Considerations: Bitumen-based systems may have higher embodied energy; newer formulations emphasize recycled felts and energy-efficient surface coatings.
Applications And Best Practices For Area Built Up Roofing
BUR is well-suited for commercial, industrial, and institutional buildings with flat or low-slope roofs. It performs well in climates with temperature extremes and exposure to wind-driven rain. Best practices include a properly prepared substrate, clean and dry surfaces, and adherence to local codes. A well-designed BUR system should account for drainage, expansion joints, and rooftop equipment clearances. For retrofits, ensure compatibility with existing decks and any vapor barriers. In areas with heavy foot traffic or maintenance equipment, a durable ballast layer or more robust cap sheet is recommended.
Installation Process Overview
The installation of Area Built Up Roofing typically follows these stages. First, the roof deck is inspected and repaired as needed, with any planks or fasteners addressed. Next, the substrate is primed, and the first ply of asphalt-saturated felt is installed using a hot asphalt or cold adhesive, depending on the system. Additional plies are added in alternating layers with binder between each sheet. The top layer is finished with a protective cap sheet and ballast or a reflective coating. If a ballast is used, ensure it is evenly distributed to prevent movement during high winds. On certain projects, a spray-applied or self-adhering top layer may replace traditional cap sheets for improved UV resistance and faster installation.
Maintenance And Longevity
Proactive maintenance extends BUR life and performance. Regular inspections should identify blisters, ridges, fishmouths, and signs of poor adherence. Address ponding water and ensure drainage paths remain clear. Replacing damaged plies or re-applying a protective cap and surface coating can extend service life. Cleaning debris and inspecting edge detailing helps prevent edge rot and wind uplift. In corrosive environments, choose high-quality, moisture-resistant felts and surface coatings designed to resist chemical exposure. Most BUR systems offer 15 to 30 years of service with proper maintenance, with some systems lasting longer under favorable conditions.
Sustainability And Energy Considerations
Modern BUR options emphasize energy efficiency and environmental responsibility. Reflective surface coatings and cool roof technologies reduce cooling loads by reflecting solar radiation, which can lower energy bills. Some assemblies incorporate recycled or reclaimed asphalt and reinforcement materials to reduce embodied energy. Proper ventilation and insulation contribute to overall building efficiency, while long-term durability minimizes replacement frequency and waste. When selecting a BUR system, consider life-cycle cost analyses that account for maintenance, energy savings, and potential rebates for energy-efficient roofing.
Common Problems And Troubleshooting
- Blisters: Caused by trapped moisture or air; alleviate by reheating and resealing the affected area or replacing compromised plies.
- Ridge And Buckling: Result of substrate movement or poor adhesion; inspect for substrate flatness and reapply adhesive where needed.
- Ponding Water: Leads to accelerated aging; improve drainage or add ballast and ensure proper deck slopes.
- Granule Loss On Surface: Indicates UV exposure or physical wear; recoat or replace surface layer to restore protection.
- Edge Deterioration: Can cause leaks; reseal edges and ensure flashing systems are intact.
Choosing A Contractor And Cost Considerations
Selecting a qualified contractor is critical for BUR performance. Look for licensed roofers with BUR experience, a proven portfolio, and strong references. Request written estimates detailing material types, ply count, application method (hot vs. cold), ballast or cap options, and warranty terms. Typical costs depend on location, roof size, ply count, and reinforcement materials, with long-term savings from energy efficiency and lower maintenance needs. Ensure a detailed project plan includes substrate preparation, weather contingencies, and a maintenance schedule to maximize the return on investment.