Asphalt Built Up Roofing: Pros, Installation, and Maintenance

Asphalt built up roofing, commonly referred to as BUR roofing, is a time-tested roofing system that blends multiple ply layers with asphalt to create a durable, weather-resistant surface. This article explores what BUR roofing is, its key components, advantages and drawbacks, typical applications, installation steps, maintenance practices, and common issues. Readers will gain practical guidance for choosing, installing, and maintaining asphalt built up roofing on commercial and residential projects in the United States.

What Is Asphalt Built Up Roofing

Asphalt built up roofing is a multi-ply system composed of alternating layers of reinforcing sheets and waterproofing asphalt, topped by a protective surface. The typical BUR assembly includes plies (felts or reinforcing sheets), asphalt waterproofing, a reinforcing ply, and a ballast or surfacing layer such as cap sheets, granule surfacing, or coatings. This structure creates redundancy, resilience against ponding water, and excellent resistance to environmental exposure.

Key Components And How They Work

The performance of BUR roofing hinges on its layered design. The reinforcing plies provide tensile strength, while the asphalt functions as the waterproofing sealant between layers. A reflective or mineral granule surface protects the roof from UV damage and serves as ballast to stabilize the assembly in wind. On low-slope or flat roofs, BUR systems excel at shedding water and withstanding hail and foot traffic when properly installed.

Benefits Of Asphalt Built Up Roofing

• Durability: Multiple plies offer redundancy, reducing the risk of leaks.
• Water Resistance: Robust waterproofing with a proven track record for long-term protection.
• Wind Resistance: Thick, layered construction resists uplift in high-wind areas.
• Repairability: Localized repairs can extend the system’s life without full replacement.
• Versatility: Suitable for various substrates, including concrete, metal, and wood decks.
• Proven Track Record: Widely installed on commercial buildings and some residential projects, with many manufacturers offering warranties.

Typical Applications And Suitability

BUR roofing is commonly used on flat or low-slope roofs in commercial, industrial, and larger residential buildings. It performs well in environments with temperature fluctuations, ponding water, and exposure to UV radiation. In retrofit projects, BUR can be added over existing roof systems to extend life. It is less common on steep-sloped residential roofs, where asphalt shingles or metal roofing may be preferred for aesthetics and weight considerations.

Installation Process Overview

Professional BUR installation follows a sequence designed for long-term performance. First, the roof deck is prepared and any insulation or substrate is inspected. Next, hot asphalt is applied to bond each reinforcing ply, with a new ply added and sealed to the previous one. After the specified number of plies, a cap sheet and ballast or surfacing are installed. Finally, the roof is sealed, flashed, and tested for leaks. Proper ventilation, asphalt temperature control, and equipment handling are essential to prevent damage and ensure adhesion.

Maintenance And Lifespan

Regular inspections are vital for BUR systems. Look for blistering, ridging, loose granules, bubbling, or signs of membrane deterioration. Cleaning gutters and downspouts helps prevent ponding and moisture buildup. Over time, granule loss or asphalt oxidation may necessitate recoating, partial resurfacing, or eventual replacement. A well-maintained BUR system commonly lasts 20 to 40 years, depending on climate, traffic, and maintenance practices.

Common Problems And Solutions

• Ponding Water: Ensure proper slope and drainage; reseal or add cap sheets if necessary.
• Granule Loss: Recoat with compatible sealants or install a new surfacing to restore UV protection.
• Blistering Or Bubbling: Investigate substrate moisture, repair leaks, and reseal affected areas.
• Cracking Or Delamination: Partial replacement of affected plies or complete re-roofing in severe cases.
• Flashing Leaks: Reflash joints around chimneys, vents, and edges to restore integrity.

Weather Considerations And Longevity

BUR systems perform well in a range of climates but require proper installation to maximize longevity. In hot climates, asphalt aging can accelerate; in cold regions, freeze-thaw cycles may impact roof assemblies. Temperature-controlled application and appropriate moisture protection during installation are critical. Periodic inspections after severe weather help identify issues early and prevent major leaks.

Environmental And Energy Considerations

Asphalt built up roofing contributes to heat absorption unless a reflective or cool surfacing is used. Reflective cap sheets or reflective coatings can reduce cooling loads for the building. Some BUR systems incorporate recycled asphalt content and other sustainable practices. When choosing BUR, consider energy efficiency, material recyclability, and the potential for roof-mounted solar installations in the future.

Cost Factors And Budgeting

Initial costs for BUR systems are typically higher than single-ply membranes but can be competitive with other built-up or metal roof options when durability and life expectancy are considered. Long-term costs include maintenance, potential repairs, and eventual replacement. A thorough life-cycle cost analysis helps building owners compare BUR against alternatives in the U.S. market.

Maintenance Plan And Best Practices

A structured maintenance plan should include annual roof inspections, prompt repair of blisters or leaks, cleaning of debris and drainage paths, and timely resealing of flashings. Documentation of all work, warranties, and contractor notes supports informed decision-making for future maintenance or replacement. Training maintenance staff on recognizing early signs of wear improves BUR performance over time.

Frequently Asked Questions

1. How long does an asphalt built up roof typically last? Typical lifespans range from 20 to 40 years with proper maintenance.
2. Is BUR roof suitable for residential homes? It is more common on commercial roofs, though some larger residences use BUR with appropriate detailing.
3. Can BUR be installed over existing roofs? Yes, with proper inspection and preparation, BUR can be installed over suitable existing roof substrates.
4. What maintenance steps are essential for BUR roofs? Regular inspections, debris removal, prompt leak repairs, and resealing or recoating as needed.
5. Are there eco-friendly BUR options? Reflective surfacing and recycled materials can improve environmental performance.