The Original Commercial Roofing System
built-up roofing has protected commercial buildings for over 150 years, earning its reputation as the most time-tested flat roofing system available. By alternating layers of bitumen and reinforcing fabrics, BUR creates a thick, monolithic membrane that provides unmatched redundancy—if one layer fails, multiple backup layers maintain waterproofing. While newer systems offer certain advantages, no other roofing system matches BUR's proven track record, making it the choice for critical facilities where failure is not an option.
BUR System Advantages
Built-Up Roofing Components
Base Sheet
Fiberglass or organic felt mechanically attached to deck. Creates stable substrate for subsequent layers.
Bitumen Layers
Hot asphalt or coal tar provides waterproofing. Applied at 400-450°F for immediate bonding.
Ply Sheets
Reinforcing felts between bitumen layers. Creates multiple waterproof barriers for redundancy.
Surfacing
Gravel, slag, or coating protects from UV and weather. Provides fire resistance and extends life.
Flood Coat
Heavy final bitumen application embeds surfacing. Creates wearing surface for maximum durability.
Cap Sheet Option
Mineral-surfaced sheet alternative to gravel. Lighter weight with easier maintenance.
BUR vs Modern Systems
Redundancy
BUR's multiple layers provide unmatched leak protection. Single-ply systems have no backup if membrane fails.
Durability
Gravel surface protects from hail, foot traffic, and UV. Outlasts exposed membrane systems in harsh conditions.
Fire Resistance
Gravel surfacing provides superior fire protection. Self-extinguishing and prevents fire spread.
Installation
Hot application requires experienced crews and safety protocols. More labor-intensive but creates stronger system.
Weight
BUR adds 2.5-6.5 lbs/sq ft requiring structural evaluation. Modern systems weigh 0.5-1.5 lbs/sq ft.
Application Process
Deck Preparation
Prime concrete or secure insulation. Ensure smooth, dry substrate for optimal adhesion.
Base Sheet Installation
Mechanically fasten or adhere base sheet. Overlap seams 2-4 inches for continuity.
Hot Bitumen Application
Mop asphalt at 400-450°F between layers. Maintain temperature for proper adhesion.
Ply Sheet Embedding
Roll reinforcing felts into hot bitumen. Eliminate air pockets and wrinkles.
Layer Repetition
Apply 3-5 alternating layers total. Each adds redundancy and thickness.
Surfacing Application
Flood coat and embed gravel or apply cap sheet. Ensures UV protection and durability.
Best Applications for BUR
- High-Traffic Roofs - Gravel surface handles unlimited foot traffic
- Critical Facilities - Redundant layers ensure continuous protection
- Fire-Sensitive Buildings - Superior fire resistance with gravel surfacing
- Large Warehouses - Cost-effective for expansive roof areas
- Historic Buildings - Traditional system maintains architectural integrity
- Chemical Plants - Coal tar BUR resists chemical exposure
Maintenance & Longevity
Gravel Maintenance
Redistribute gravel annually to maintain even coverage. Replace lost gravel to maintain UV protection and ballast.
Drainage Issues
BUR tolerates ponding better than most systems. Still requires clearing drains to prevent excessive loading.
Repair Methods
Damaged areas cut out and rebuilt with new layers. Patches integrate fully with existing system.
Restoration Options
At 20 years, add cap sheet or coating over existing. Extends life 10-15 years at fraction of replacement cost.
Leak Detection
Multiple layers make leak location challenging. Infrared scanning or electrical testing identifies breach points.
Modern BUR Innovations
Today's built-up roofing incorporates modern materials while maintaining traditional reliability. Polymer-modified asphalts improve flexibility and adhesion. Fiberglass felts provide superior strength with less weight than organic felts. Cool roof surfacing options include white gravel or reflective cap sheets that reduce cooling costs by 20-30%. These innovations address BUR's traditional limitations while preserving its unmatched redundancy and proven performance.