The article explains what a residential built-up roof (BUR) is, why homeowners choose it, and how it compares to other roofing systems. It covers materials, installation steps, lifespan, common problems, cost considerations, and maintenance tips to help homeowners make informed decisions about BUR for their homes.
| Topic | Quick Facts |
|---|---|
| Typical Composition | Multiple Bitumen And Felt Layers With A Surfacing |
| Best For | Low-Slope Residential Roofs And Roofs With Heavy Foot Traffic |
| Average Lifespan | 20–30 Years With Proper Maintenance |
| Approximate Cost | $4–$10 Per Square Foot Installed (Varies By Region) |
What Is A Residential Built-Up Roof (BUR)?
A residential built-up roof is a multi-layer roofing system commonly used on low-slope residential buildings. It consists of alternating layers of roofing felt or glass fiber and hot-applied or cold-applied bitumen, finished with a protective surfacing such as gravel, mineral cap sheet, or reflective coating. Built-up roofing is known for its redundancy and waterproofing reliability, making it a long-standing option for flat or nearly flat roofs.
Key Components And Materials
Understanding BUR requires knowing the main components: the felt or membrane plies, the bitumen (asphalt or coal-tar), the flashing details, and the surface layer. Each component contributes to the roof’s performance and longevity.
Felt And Reinforcement
Felt plies are typically organic or fiberglass-based sheets that provide structural reinforcement. Multiple plies (often 3–5) create a durable layered barrier against water infiltration and mechanical damage.
Bitumen Types
Bitumen can be hot-applied asphalt, coal-tar pitch, or cold-applied modified bitumen adhesives. Hot-applied asphalt is the most common for modern BUR because of cost and availability. Coal-tar pitch resists chemical exposure but is less common due to handling concerns.
Surfacing Options
Common surfacings include loose-laid gravel, crushed stone, mineral-surfaced cap sheets, and reflective coatings. Surfacing protects the bitumen from UV damage and physical wear. Choosing the right surfacing balances protection, drainage, and aesthetic needs.
Advantages Of Built-Up Roofing For Homes
Built-up roofing has several benefits that make it attractive for residential low-slope roofs. These pros should be weighed against modern alternatives like single-ply membranes (TPO, EPDM) and modified bitumen systems.
- Proven Durability: BUR systems have decades-long track records when installed and maintained properly.
- Redundancy: Multiple plies reduce the likelihood of leaks and localized failures.
- Excellent Waterproofing: Hot-applied systems create seamless layers that resist water penetration.
- Good For Foot Traffic: Gravel or stone surfacing protects the membrane from punctures and foot traffic.
Limitations And Considerations
Despite strengths, BURs have limitations. They tend to be heavier than single-ply roofs, may require fire and odor precautions during installation, and can be more labor-intensive to apply. Siting, structural capacity, and local building codes influence whether BUR is appropriate.
Weight And Structural Requirements
Built-up roofs can add significant dead load to a structure, especially with gravel surfacing. An engineer may be needed to verify roof framing. Older homes often require assessment before BUR installation.
Installation Complexity
Hot-applied BUR uses kettles of molten asphalt, requiring skilled crews and safety controls. Cold-applied systems are available for situations where open-flame work is restricted. Professional installation affects performance and warranty validity.
Installation Process Overview
The BUR installation sequence requires preparation, membrane application, flashing, and surfacing. Proper sequencing and attention to details are critical to achieving expected lifespan and performance.
- Deck Preparation: Ensure the deck is clean, dry, and structurally sound; install insulation and vapor barriers as needed.
- Base Sheet Installation: Apply a base sheet mechanically or with bitumen to provide a uniform foundation.
- Build-Up Plies: Alternately mop or flood-coat with bitumen and roll-in felt plies until specified thickness is reached.
- Flashing: Integrate flashings at parapets, curbs, drains, vents, and transitions to prevent edge and penetration leaks.
- Surfacing: Finish with gravel, cap sheet, or reflective coating to protect the system from UV and abrasion.
Lifespan, Performance, And Longevity
When correctly installed and maintained, BUR roofs commonly last 20–30 years or longer. Lifespan depends on ply count, surfacing type, climate exposure, and maintenance frequency.
Factors That Extend Life
Proactive maintenance, good drainage, periodic inspections after storms, and timely repairs of blisters or splits can significantly extend service life. Roof coatings and re-cover options can add years without full replacement.
Common Failure Modes
Failures typically arise from ponding water, flashings that have deteriorated, mechanical damage, or shrinkage and separation of plies. Addressing drainage problems early reduces replacement risk.
Cost Breakdown And Financial Considerations
Costs vary by region, roof complexity, and material choices. Typical installed BUR costs range widely, influenced by labor intensity and surfacing.
| Cost Component | Estimate |
|---|---|
| Materials | $1.50–$5.00 Per Sq Ft |
| Labor/Installation | $2.00–$4.00 Per Sq Ft |
| Removal Of Old Roof | $0.50–$2.00 Per Sq Ft |
| Total Installed | $4–$10 Per Sq Ft (Typical Range) |
Homeowners should obtain multiple bids and verify contractor licensing and insurance. Warranties vary; manufacturer and workmanship warranties offer different coverages. Comparing life-cycle cost, not just upfront price, provides a clearer financial picture.
Maintenance Checklist And Repair Tips
Regular maintenance preserves performance and reduces long-term costs. Homeowners or property managers should follow a consistent inspection and maintenance routine.
- Biannual Inspections: Check for ponding water, blisters, seam separations, and damaged surfacing.
- Post-Storm Checks: Inspect for displaced gravel, punctures, and torn flashing after storms.
- Drain Maintenance: Keep drains, scuppers, and gutters clear to prevent ponding.
- Spot Repairs: Address small splits or blisters immediately to prevent moisture intrusion.
- Re-Coating: Apply reflective or protective coatings when weathering appears to slow aging.
Comparing BUR With Other Low-Slope Options
Homeowners comparing options should consider performance, cost, weight, and long-term maintenance. Built-up roofing competes with modified bitumen, EPDM, TPO, and PVC systems.
| System | Main Advantage | Main Drawback |
|---|---|---|
| Built-Up Roofing (BUR) | Durability And Redundancy | Heavy, Labor-Intensive |
| Modified Bitumen | Flexible, Easier Patching | Can Be Less Reflective Without Coating |
| EPDM | Cost-Effective, Lightweight | Seam Vulnerabilities Over Time |
| TPO/PVC | Reflective And Energy-Efficient | Newer Tech—Performance Varies By Product |
Choosing A Contractor And Ensuring Quality
Selecting the right contractor is essential for BUR performance. Homeowners should verify credentials, references, and project oversight practices.
- License And Insurance: Confirm the contractor holds appropriate state and local licenses and carries liability and workers’ comp insurance.
- References And Portfolio: Ask for recent projects similar in size and scope and contact references.
- Written Proposal: Require a detailed scope, materials list, warranty terms, and clear timeline in writing.
- On-Site Supervision: Confirm who will supervise installation and how quality control will be documented.
Code, Permits, And Sustainability Considerations
Local building codes may require permits for BUR installation, especially when fire ratings, insulation, or structural upgrades are involved. Some jurisdictions incentivize cool roofs or reflective coatings to reduce heat island effects. Energy-efficient surfacing or additional insulation can improve home comfort and reduce cooling costs.
When To Consider Replacement Vs. Repair
Decisions hinge on age, extent of damage, and remaining life expectancy. Small localized leaks often respond well to repairs, while pervasive ply delamination, extensive ponding, or multiple repairs over short intervals indicate replacement. An objective roof assessment by a qualified inspector helps determine the most cost-effective path.
Resources For Homeowners
Homeowners should consult reputable sources such as the National Roofing Contractors Association (NRCA), local building departments, and manufacturer technical documents for specifications and best practices. Combining professional advice with documented warranties and clear contracts reduces project risk.
For further reading, homeowners can review NRCA guides, manufacturer installation manuals, and local code resources to ensure compliance and optimal roof performance.