The following article explores built up roofing material (BUR), a traditional and durable option for flat and low-slope roofs. It covers components, installation, benefits, drawbacks, maintenance, and environmental considerations. Readers will gain practical guidance on selecting BUR systems for commercial, industrial, or residential applications while understanding how this roofing material performs in varied climates and building codes.
What Is Built-Up Roofing Material?
Built up roofing material, or BUR, is a multilayer system composed of alternating layers of bitumen (asphalt or coal tar pitch) and reinforcing fabrics, topped with a protective surface such as gravel or a cap sheet. The result is a durable, weather-resistant roof that forms a weatherproof membrane through multiple plies. BUR systems are commonly used on flat or low-slope roofs due to their robust wind resistance and long track record.
Key Components Of BUR Systems
A BUR system typically includes several essential elements that work together to provide protection and longevity.
- Insulation beneath the BUR plies improves thermal performance and energy efficiency.
- Bitumen Plies are the main waterproofing layers, often installed in 3 to 5 plies depending on climate and expected exposure.
- Reinforcement fabrics such as fiberglass or organic mats add strength and tear resistance to each ply.
- Adhesive or Soffit Moppings secure plies and help prevent delamination in varying temperatures.
- Surfacing options include loose gravel, mineral granules, or a reflective cap sheet that shields the membrane from UV radiation and weathering.
- Sound and Fire Considerations provide additional safety and comfort, especially in occupancy-heavy buildings.
Advantages And Disadvantages
Understanding the trade-offs helps in choosing BUR for a specific project.
- Durability BUR offers excellent waterproofing due to multiple plies and a robust surface, making it suitable for areas with heavy rainfall or temperature swings.
- Proven Track Record The system has decades of field performance in diverse climates, contributing to long service life when properly installed and maintained.
- Thermal Performance When paired with insulation, BUR contributes to energy efficiency and indoor comfort.
- Maintenance Needs BUR requires periodic inspections and occasional restorative work, which can add to long-term costs.
- Weight And Installation The material is heavier than some modern single-pply systems, impacting structure load calculations and requiring skilled labor during installation.
- Environmental Footprint Bitumen and asphalt components have environmental considerations, though recycling and advanced mats are improving sustainability.
Installation Considerations And Best Practices
Proper installation is critical to maximize BUR performance and avoid common failure modes.
- Surface Preparation Ensure a clean, dry, and smooth substrate with appropriate insulation and ventilation.
- Ventilation And Drainage Adequate attic or deck ventilation prevents moisture buildup that can compromise the BUR.
- Plies And Temperature Install plies within recommended temperature ranges to optimize adhesion and flexibility.
- Vent Opening And Flashings Use compatible flashing details around penetrations, edges, and terminations to prevent water intrusion.
- Quality Control Regular inspection during installation helps verify ply alignment, adhesion, and surface protection.
Maintenance And Longevity
Ongoing care extends BUR life and reduces the risk of leaks.
- Routine Inspections Check for blisters, cracks, indicative of underlying moisture or poor adhesion, and monitor edge detailing.
- Surface Protection Gravel or cap sheets should be inspected for displacement or loss; replace or reseal as needed.
- Vegetation Control Remove nearby vegetation and debris to prevent moisture retention and fire hazards.
- Repair Methods Prompt patching of damaged plies and resealing around flashings preserve system integrity.
- Lifecycle Planning Typical BUR lifespans range from 20 to 40 years depending on climate, maintenance, and installation quality.
Common Myths And Truths
Addressing common misconceptions helps in making informed decisions about BUR.
- Myth: BUR is outdated and obsolete. Truth: While newer single-ply systems exist, BUR remains a reliable, time-tested choice for durability and weather resistance.
- Myth: BUR is prohibitively heavy. Truth: Structural loads are a consideration, but modern BUR assemblies are designed to meet building codes when properly engineered.
- Myth: BUR cannot be energy efficient. Truth: When paired with proper insulation and reflective surfacing, BUR contributes to energy savings and thermal comfort.
Environmental And Energy Considerations
Choosing BUR with sustainability in mind can reduce environmental impact.
- Materials Recycled asphalt, alternative bitumen blends, and lighter cap sheets are increasingly common.
- Energy Efficiency Reflective surfaces and proper insulation lower cooling loads in hot climates.
- Waste Management During replacement or repairs, proper disposal and recycling of old BUR components minimize landfill use.
- Indoor Air Quality Proper ventilation during installation prevents exposure to fumes; low-VOC sealants and adhesives improve indoor air outcomes.
Choosing The Right BUR System
Selecting a BUR system requires assessing climate, building codes, budget, and long-term maintenance needs.
- Climate Fit Regions with freeze-thaw cycles or high UV exposure benefit from multiple plies and protective surfaces.
- Code Compliance Ensure compatibility with local fire ratings, wind uplift requirements, and insulation standards.
- Maintenance Plan Establish a routine inspection and repair program to maximize longevity.
- Contractor Qualification Hire installers with BUR experience, proper safety protocols, and verified track records.
Key Takeaways: Built up roofing material remains a dependable choice for flat and low-slope roofs due to its durability, proven performance, and adaptability when paired with proper insulation and maintenance. Careful installation, routine upkeep, and consideration of environmental factors enhance its value and lifespan for commercial, industrial, and residential applications.