Area Built Up Roofing: A Comprehensive Guide

Area Built Up Roofing refers to a traditional roofing system that uses multiple layers of asphalt-saturated felt and protective cap sheets to create a durable, weatherproof surface. This guide explains what area built up roofing is, how BUR systems work, their advantages, installation considerations, maintenance needs, and what to expect when selecting a contractor. It emphasizes practical, US-focused insights to help property owners and managers evaluate BUR for commercial, industrial, and larger residential projects.

What Is Area Built Up Roofing?

Area Built Up Roofing, commonly known as BUR, is a membrane system constructed from alternating layers of reinforcing fabrics (felts) and asphaltic or coal-tar pitch, topped with a durable cap sheet. The number of plies typically ranges from three to five, with reinforcing sheets embedded in hot asphalt or cold adhesive. A protective surface layer, such as embedment gravel, a mineral granule cap sheet, or reflective coatings, shields the membrane from UV exposure and weathering. BUR systems are versatile, offering dependable waterproofing for flat or low-slope roofs common on American commercial buildings.

How BUR Roofing Works

BUR systems seal against water intrusion through multiple layers that provide redundant protection. Each ply adds strength and flexibility, helping the roof resist wind uplift and thermal movement. The uppermost surface protects against UV degradation and physical damage. When properly installed, the system creates a continuous, seamless barrier that accommodates seasonal expansion and contraction without cracking. Regular maintenance keeps joints and flashings intact, preserving long-term performance.

Materials And Layers

A standard BUR assembly includes:

• Insulation board or a substrate to provide thermal efficiency and a stable base
• Reinforcing felt plies embedded in hot or cold asphalt
• Adhesive or self-sticking ply reinforcing layers for additional strength
• Cap sheet with a surfaced protection layer
• Finish surface such as gravel, mineral granules, or reflective coatings

Common asphalt choices include coal tar pitch and petroleum asphalt, selected based on local codes, climate, and contractor preference. Modern BUR systems may incorporate modified bitumen and ply configurations to improve performance and ease of installation.

Applications And Suitability

BUR is well-suited for flat or low-slope roofs on large commercial complexes, warehouses, multi-tenant buildings, and institutional facilities. It performs reliably in diverse climates, from hot southern regions to cold northern conditions, provided proper ventilation, drainage, and flashing details are addressed. While newer systems like single-pply membranes gain popularity, BUR remains a durable, cost-effective option for projects requiring robust waterproofing and long service life.

Benefits Of Area Built Up Roofing

• Durability: multiple layers provide redundancy against leaks
• Weather Resistance: excellent protection from wind, hail, and temperature fluctuations
• Proven Track Record: decades of performance in varied U.S. climates
• Repairability: localized repairs can extend system life
• Thermal Versatility: compatible with insulation upgrades and reflective surface options

Installation Considerations

Proper BUR installation hinges on surface preparation, ply installation sequence, and weather. Key steps include cleaning the substrate, ensuring proper insulation and drainage, and applying plies with correct asphalt temperatures to avoid air pockets. Flashings around seams, penetrations, and roof edges require meticulous detailing. Local codes may dictate vapor barriers, fire ratings, and material sources. A skilled contractor will sequence ply application to minimize thermal stress and verify with a final water test after completion.

Maintenance And Repairs

Routine maintenance focuses on inspecting for blisters, wrinkles, exposed felt, and surface damage. Gravel or cap sheet wear should be monitored, and UV-damaged areas may need surface coatings. Repairs often involve replacing damaged plies, resealing flashings, or applying new cap sheets. Periodic inspections after heavy storms or temperature extremes help catch issues early. Proper grading, drainage, and roof penetrations should be checked to prevent standing water and accelerated wear.

Energy Efficiency And Sustainability

BUR systems can contribute to energy savings when combined with reflective or cool roof coatings, reducing rooftop heat gain. Some BUR assemblies are designed to accommodate additional insulation for better R-values, enhancing overall building performance. When evaluating sustainability, consider recycled content in felts, the environmental impact of asphalt production, and the potential for hot asphalt emissions during installation. Choosing reflective cap sheets or coatings can further improve energy performance in hot climates.

Common Issues And Troubleshooting

Typical problems include blisters from trapped moisture, wrinkles from improper ply placement, membrane cracking at details, and flashing failures around edges or penetrations. Weathering can cause cap sheet granule loss, reducing UV protection. Regular inspections, prompt patching, and re-sealing vulnerable areas help minimize damage. In seismic zones or areas with heavy wind, ensuring secure edge details and secure ballast is crucial to prevent uplift.

Choosing A Contractor And Cost Considerations

When selecting a contractor for Area Built Up Roofing, prioritize licensed firms with BUR experience, recent project references, and clear warranty terms. Request a detailed scope of work, including ply counts, materials, surface finish, insulation specifications, and repair protocols. Compare long-term lifecycle costs, not just initial price, and verify local code compliance. Typical BUR systems offer a favorable balance of installed cost, durability, and repairability for many mid- to large-scale projects.

Frequently Asked Questions

• How long does BUR typically last? With proper maintenance, BUR can last 20 to 40 years depending on climate and installation quality.
• Can BUR be installed over existing roofs? Often yes, if the substrate is sound and drainage is adequate, but some projects require removal.
• Is BUR recyclable? Upcycling options exist, though recycling rates vary by region and material suppliers.