If you’re researching roofing options for a flat or low-slope structure, you’ve likely come across the term built up roof. Known for its durability and time-tested performance, this multi-layered system is a popular choice for both residential and commercial properties.
In this guide, we’ll break down what a built-up roofing system is, how it works, and whether it’s the right solution for your property—so you can make a confident, informed decision.
What you’ll learn:
- How Built-Up Roofing Systems Work
- Benefits of Built-Up Roofing Systems
- Drawbacks and Considerations
- Built-Up Roof vs. Other Flat Roofing Systems
- Who Should Consider a Built-Up Roof?
- FAQ About Built-Up Roofing Systems
How Built-Up Roofing Systems Work
Built-up roofing systems, commonly referred to as BUR, rely on a time-tested method of layering materials to create a durable, weather-resistant surface. Ideal for flat or low-slope roofs, these systems are designed to provide long-lasting protection through multiple layers that work together to seal, insulate, and reinforce the roof structure.
Understanding the components and installation process can help property owners appreciate the value and reliability of a built-up roof.
Key Components (Asphalt, Felt, Gravel, Insulation)
A built-up roof consists of several key materials layered in a specific sequence, each serving a unique purpose within the system. You can learn more about the types of materials used in built-up roofing systems from the National Roofing Contractors Association.
- Asphalt or Bitumen: This waterproofing agent acts as the adhesive and protective barrier between layers. It can be hot-applied or cold-applied, depending on the project’s specifications.
- Roofing Felt or Ply Sheets: These are fabric layers, typically made of fiberglass or organic materials, that are embedded in asphalt. They provide tensile strength and act as reinforcement within the system.
- Gravel or Cap Sheet Surface: The topmost layer protects the roof from UV radiation and mechanical damage. It also improves fire resistance and reduces wear from foot traffic or environmental exposure.
- Insulation Board (optional but common): Installed beneath the membrane layers, insulation helps regulate indoor temperatures and boosts energy efficiency—especially important for commercial and climate-sensitive properties like those using roof insulation.
To dive deeper into how these materials interact layer by layer, explore our breakdown of built-up roof layers.
Installation Process Overview
The process of installing a built-up roof is meticulous and requires professional expertise to ensure long-term performance and code compliance. Here’s an overview of how it’s typically done:
- Surface Preparation: The existing roof surface is cleaned, and any damaged materials are removed. In retrofit cases, old roofing may be torn off down to the deck.
- Insulation Installation: If specified, insulation boards are installed and secured to improve thermal performance.
- Base Sheet Application: A base sheet is laid down and adhered using asphalt or mechanical fasteners to establish the foundation for the system.
- Layering Ply Sheets and Asphalt: Multiple layers of ply sheets are applied, each set in hot or cold asphalt. This multi-ply system builds redundancy and increases waterproofing capacity.
- Surfacing: The final layer consists of gravel embedded in asphalt or a mineral-surfaced cap sheet. This protects the membrane and reflects sunlight to reduce heat absorption.
Due to the complexity of materials, application methods, and safety requirements—especially with hot asphalt—BUR installation should always be handled by certified professionals. At RayPro, our licensed crews deliver precise, code-compliant installations backed by over 17 years of experience and industry-leading warranties.
Learn more about our professional roofing installation services →
Benefits of Built-Up Roofing Systems
Built-up roofing systems have stood the test of time for a reason. Their multi-layered construction delivers reliable protection, energy efficiency, and long-term value—making them a smart investment for both homeowners and commercial property managers.
Below are the core benefits that make BUR a top choice for flat and low-slope roofs.
Proven Durability and Longevity
One of the most recognized advantages of a built-up roof is its durability. The layered design—typically consisting of alternating asphalt and reinforcing fabrics—creates a robust, thick membrane that can withstand decades of exposure to harsh weather.
From intense UV radiation and heavy rain to foot traffic from maintenance crews, BUR systems are engineered to perform reliably over the long haul. Many well-maintained built-up roofs last 20–30 years or more, with some exceeding 40 years in mild climates.
For a full breakdown of what affects BUR lifespan—including maintenance, weather, and materials—see our dedicated guide: How Long Does a Built-Up Roof Really Last?
Excellent Waterproofing and Insulation
Thanks to its redundant layering, a built-up roofing system provides outstanding waterproofing. Each ply adds an extra barrier against moisture intrusion, making leaks far less likely compared to single-layer systems. This is especially important for flat roofs, where water tends to pool rather than run off.
Beyond moisture resistance, BUR systems also offer excellent thermal performance, helping to regulate indoor temperatures and reduce utility costs.
For more insight, the Department of Energy outlines the ways roof insulation contributes to building energy efficiency in detail.
The asphalt and insulation layers help regulate indoor temperatures, reducing heat gain in summer and heat loss in winter.
This contributes to improved comfort and lower energy bills—benefits that are especially important for commercial buildings and homeowners in hot, storm-prone states like Florida.
Explore more energy-efficient roofing solutions →
Low Maintenance and Cost-Effective Over Time
While BUR systems may require a larger upfront investment than some alternatives, they offer substantial savings over time. Their durability means fewer repairs, lower risk of emergency patching, and extended intervals between replacements.
This makes BUR particularly attractive for larger buildings—such as warehouses, apartment complexes, or office structures—where long-term cost predictability and minimal disruption are critical.
Additionally, their built-in redundancy means small surface damage rarely compromises the entire system, allowing for targeted maintenance when needed. With proper care and periodic inspections, a BUR system can deliver decades of low-maintenance performance, adding long-term value to the property.
Learn more about our residential roof repair solutions →
Drawbacks and Considerations
While built-up roofing systems offer strong advantages in durability and performance, they aren’t the ideal solution for every property. Like any roofing option, BUR comes with specific considerations that should be evaluated before moving forward.
Being aware of these potential drawbacks ensures you can make an informed decision based on your building’s structure, timeline, and usage.
Weight and Structural Requirements
Built-up roofs are heavy—significantly more so than single-ply systems like TPO or EPDM. The multiple layers of asphalt, felts, and aggregate add considerable weight, which can pose challenges for lightweight or older structures not designed to handle the load.
Before installation, a structural assessment is essential to ensure the building can safely support a BUR system. In some cases, modifications or reinforcements may be required, which could impact overall cost and roofing project timeline.
Installation Time and Weather Sensitivity
Unlike some modern roofing systems that can be installed quickly, BUR requires more time to apply due to its multi-layered construction. Each layer must be precisely installed and properly adhered, often using hot asphalt, which extends the project duration.
Additionally, weather plays a critical role—BUR installation is best performed in dry, mild conditions to ensure proper adhesion and material performance.
The Whole Building Design Guide offers more on roofing best practices in various climate conditions that affect installation timelines and durability.
Rain or high humidity can delay work, especially in regions like Florida where sudden storms are common.
Odors and Fumes During Installation
Hot-applied asphalt emits strong odors and fumes during installation, which can be disruptive—particularly in occupied commercial buildings like offices, schools, or retail spaces.
While these fumes are temporary and generally not hazardous with proper ventilation, they can affect indoor air quality and may require scheduling considerations or communication with tenants. For sensitive environments, alternative cold-applied or low-odor systems may be worth exploring.
Built-Up Roof vs. Other Flat Roofing Systems
When evaluating flat roof options, it’s important to understand how a built-up roof (BUR) compares to other common systems. Each roofing type has its own strengths, weaknesses, and ideal applications.
Below is a breakdown of how BUR stacks up against modified bitumen, TPO, and EPDM—helping you determine which system best fits your property’s needs.
BUR vs. Modified Bitumen
Modified bitumen is often considered a modern evolution of the traditional built-up roofing system. Like BUR, it’s typically applied in layers and uses asphalt-based materials—but with some key differences:
- Material Composition: Modified bitumen uses factory-fabricated sheets that include modifiers (like APP or SBS) to enhance flexibility and performance. BUR uses alternating layers of hot asphalt and ply sheets built up on-site.
- Installation: BUR requires hot asphalt or cold adhesive during installation, whereas modified bitumen can be torch-applied, cold-applied, or self-adhered, depending on the product.
- Durability: Both offer strong durability, but BUR’s multi-ply layering can offer more built-in redundancy, especially for large-scale or high-traffic roofs.
- Cost: Modified bitumen generally has a lower installation cost due to faster application, but BUR can deliver better lifecycle value due to its longer lifespan and resilience.
BUR vs. TPO & EPDM
TPO (Thermoplastic Olefin) and EPDM (Ethylene Propylene Diene Monomer) are single-ply membrane systems that have gained popularity for their ease of installation and energy-efficient properties:
- Installation Speed: TPO and EPDM systems are quicker to install than BUR, making them appealing for time-sensitive projects. If you’re comparing options, this overview of common commercial roofing membranes provides a helpful side-by-side breakdown.
- Energy Efficiency: TPO is often white and highly reflective, contributing to better energy savings in warm climates. EPDM is usually black, better for cold regions. BUR can incorporate reflective cap sheets or gravel, but it’s not inherently as reflective.
- Durability: BUR tends to have greater puncture resistance due to its multi-layer design. Single-ply systems are more susceptible to tears and punctures, particularly in high-traffic areas.
- Maintenance: Single-ply roofs are easier to inspect and repair, but may not last as long as a properly maintained BUR system.
When BUR is the Better Choice
A built-up roofing system is often the best fit when long-term performance, durability under harsh weather, and low-maintenance reliability are top priorities. It’s especially suited for:
| Criteria | Built-Up Roof (BUR) | Modified Bitumen | TPO/EPDM |
| Lifespan | 20–30+ years | 15–20 years | 10–20 years |
| Durability (Puncture & Traffic) | High | Moderate–High | Moderate |
| Installation Time | Longer | Moderate | Short |
| Energy Efficiency | Moderate (with surfacing) | Moderate | High (TPO); Low (EPDM) |
| Best for Flat/Low-Slope Roofs | Yes | Yes | Yes |
| Ideal for Commercial Applications | Yes | Yes | Yes |
| Suitable for Residential Properties | Yes (with structural support) | Yes | Yes |
BUR stands out when structural capacity allows for a heavier, more robust solution—particularly for properties in storm-prone regions or those requiring long-term, low-maintenance protection.
Who Should Consider a Built-Up Roof?
Built-up roofing systems aren’t one-size-fits-all—but for the right properties, they offer exceptional value, durability, and protection. Whether you manage commercial buildings or own a residential home with a flat or low-slope roof, BUR may be the ideal solution.
This section will help you determine if a built-up roof aligns with your specific needs and long-term goals.
Ideal for Commercial Properties with Flat Roofs
BUR systems are especially well-suited for commercial buildings with expansive flat or low-slope roof areas. Their layered construction provides enhanced durability, making them ideal for:
- Warehouses and Distribution Centers
- Retail Centers and Shopping Plazas
- Office Buildings
- Multi-Family Complexes and Apartment Buildings
These structures often face heavier foot traffic, rooftop equipment loads, and exposure to weather extremes—all conditions where BUR’s puncture resistance and waterproofing capabilities shine.
Additionally, its low-maintenance nature helps building managers minimize disruption and control operating costs.
Discover the benefits of Built-Up Roofing (BUR) systems for commercial buildings, including durability, waterproofing, and fire resistance. Learn why this time-tested flat roofing solution might be the right fit for your property.
Use Cases for Residential Flat or Low-Slope Roofs
While built-up roofs are more common in commercial settings, they can also be a great choice for certain residential properties—particularly in Florida and other storm-prone regions.
Homes with low-slope roof designs benefit from BUR’s ability to resist water intrusion and withstand wind uplift.
For homeowners looking to enhance storm resilience, reduce long-term repair costs, and improve energy efficiency, BUR offers a practical and proven solution. Proper structural assessment is key, as the system’s weight must be supported by the home’s framing.
Learn more about our storm restoration service →
Long-Term ROI for Property Owners and Managers
For owners and managers of commercial portfolios, a built-up roof can be a strategic asset. Its extended lifespan and minimal repair needs make it a cost-effective solution over decades, especially when paired with a proactive maintenance plan.
Beyond financial returns, BUR systems also contribute to peace of mind—reducing the risk of emergency roof failures and minimizing insurance claims.
For those managing multiple properties, the consistency and proven reliability of BUR installation across sites can streamline planning and budgeting.
Get the roofing or renovation solution your property needs today without the upfront burden.
Get a Quote or Consultation Today
If you’re considering a built-up roof for your home or commercial property, now is the time to take the next step. At RayPro Roofing & General Contracting, we offer free consultations to help you understand your options and determine the best roofing solution for your structure and budget.
Our team will provide a detailed assessment of your property, answer any questions you may have, and deliver a transparent quote with no hidden fees.
Whether you’re dealing with aging infrastructure, roof leaks, or planning an energy-efficient upgrade, RayPro’s expert guidance and full-service support ensure your project gets done right—on time and within budget.
Let us show you why property owners across 17 states trust RayPro with their roofing investments.
Request your free quote or book a consultation now →
Frequently Asked Questions About Built-Up Roofing Systems
A built-up roof (BUR) is a multi-layered roofing system designed primarily for flat or low-slope roofs. It consists of alternating layers of asphalt (or bitumen) and reinforcing fabrics like roofing felt or ply sheets, topped with a protective surfacing such as gravel or a mineral cap sheet.
These layers work together to provide waterproofing, durability, and insulation, making BUR a trusted solution for both residential and commercial properties.
When properly installed and maintained, a built-up roofing system can last 20 to 30 years or more. In some cases, especially with regular maintenance and favorable weather conditions, BUR systems have been known to exceed 40 years.
Their longevity is largely due to the system’s redundant layers, which enhance durability and protect against leaks and wear.
It depends on your specific needs. Built-up roofs offer superior durability and puncture resistance, especially for high-traffic commercial roofs. However, TPO and EPDM are quicker to install, lighter in weight, and may offer better reflectivity or flexibility depending on the climate.
BUR is often the better choice for long-term performance, particularly in storm-prone or high-traffic areas, while single-ply systems may be ideal for projects with tighter timelines or structural weight limitations.
Some of the main considerations include:
Weight: BUR systems are heavier and may not be suitable for all structures without reinforcement.
Installation Time: The multi-layer process takes longer to install and is best done in dry weather.
Odors: Hot asphalt used in application can produce strong fumes, which may be disruptive in occupied buildings.
Despite these factors, many property owners find the long-term benefits outweigh the initial drawbacks.
Yes—built-up roofs can be a great fit for residential homes with flat or low-slope roofs, particularly in regions like Florida where storm resilience is essential.A structural assessment is important to ensure your home can support the system’s weight before installing a built-up roof. The International Association of Certified Home Inspectors explains the importance of structural load assessments for residential roofing in their detailed guide.
When installed by a qualified contractor like RayPro, a BUR system can deliver excellent protection, energy efficiency, and long-term value for your home.
