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Commercial Built-Up Roofing

What Is Built Up Roofing? A Trusted Commercial Roofing Solution for Arizona Businesses

built up roofingWhen it comes to long-lasting, cost-effective flat roofing systems for commercial properties, built up roofing remains one of the most time-tested solutions available. Often referred to as “tar and gravel roofing,” this method has been in use for over 150 years and continues to be a popular choice for business owners in Phoenix, Casa Grande, Mesa, and beyond.

But why does built up roofing remain so widely used in commercial roofing applications? And is it the right solution for your building in Tempe, Peoria, or Avondale?

Let’s break it down.

How Built Up Roofing Works

Built up roofing is a layered system designed for flat or low-slope commercial roofs. Each system typically consists of alternating layers of roofing felt (usually fiberglass-based) and bitumen (asphalt or coal tar), which are then topped with a layer of gravel or reflective coating.

Here’s what a typical built up roofing assembly looks like:

  • Base sheet: Provides a strong foundation layer, adhered directly to the roof deck.

  • Bitumen: Either hot-applied asphalt or cold-applied adhesive is used between layers to ensure watertight integrity.

  • Ply sheets: Reinforced felts that form the waterproof core, typically applied in 3–5 layers depending on the building’s needs.

  • Surfacing: Gravel, mineral cap sheet, or a reflective coating like aluminum or elastomeric to protect from UV rays and physical wear.

This system provides exceptional waterproofing and redundancy. If one layer fails, others continue to protect the building—an essential feature for commercial properties with sensitive equipment or valuable inventory.

Key Advantages of Built Up Roofing for Commercial Buildings

Business owners in Arizona cities like Glendale, Sun City, and Surprise often choose built up roofing because it offers:

1. Proven Durability

With proper maintenance, built up roofing can last 20–30 years, even in harsh desert conditions. Its multi-layer construction gives it superior resistance to foot traffic, falling debris, and heavy rains.

2. Excellent Waterproofing

Each bitumen and felt layer is bonded to create a watertight seal. This is crucial for flat-roofed buildings in areas prone to standing water or monsoon storms like Buckeye and Queen Creek.

3. UV Resistance and Energy Savings

When finished with a reflective top coat or gravel surfacing, built up roofing reduces solar heat absorption—helping to lower cooling costs during the blistering Phoenix summer. This is an ideal strategy for businesses trying to reduce overhead.

For more insight into energy-efficient roofing, the Department of Energy’s guide on cool roofs offers helpful context.

4. Fire Resistance

Because built up roofing uses non-combustible materials, it’s a smart option for commercial kitchens, manufacturing plants, or any business with fire risk exposure.

5. Cost Efficiency

Though more labor-intensive to install than some alternatives, the long lifespan and minimal maintenance needs of built up roofing often make it a more affordable investment over time.

Why Arizona Businesses Trust Castile Roofing for Built Up Roofing

From flat retail roofs in Goodyear to warehouse facilities in Tolleson, Castile Roofing is the name that commercial property managers trust for dependable, code-compliant built up roofing installations.

We understand the localized challenges of Arizona’s desert climate—something out-of-state roofing contractors often underestimate. Between intense UV exposure, monsoon-driven flooding, and extreme thermal shifts, commercial roofing in the Valley demands more than a cookie-cutter approach.

At Castile Roofing, we:

  • Offer fully ROC-licensed roofing services for commercial and residential projects.

  • Provide roofing damage insurance assistance to help you navigate storm recovery claims.

  • Deliver precise workmanship using only top-grade materials, whether installing a new roof or retrofitting an old one.

  • Support local businesses across cities like Maricopa, New River, and Anthem.

Want to see what we’ve done in your area? Check out our work in Cave Creek and Glendale.

When Built Up Roofing Might Not Be the Best Fit

While built up roofing is a strong option for many commercial buildings, it’s not ideal for every situation.

For example:

  • It’s heavier than TPO or foam roofing, which can strain older roof decks.

  • It requires more labor and can’t be installed during rain or high humidity.

  • Installation can be disruptive, which is why timing and contractor flexibility matter. (We offer extended scheduling to work around your business hours.)

If you’re looking for a lighter, fast-install alternative, you might consider our single-ply roofing solutions or explore roof coatings as a temporary measure.

Still unsure? Our commercial specialists can walk you through every option and help you compare costs, energy performance, and long-term ROI.

Built Up Roofing vs. Other Flat Roof Systems: What’s Right for Your Commercial Property?

Choosing a roofing system for your commercial building in Phoenix, Mesa, or Scottsdale isn’t just about cost—it’s about performance, maintenance, and longevity. While built up roofing remains a gold standard for many businesses, it’s worth comparing how it stacks up against newer materials like TPO, EPDM, and spray polyurethane foam (SPF).

Let’s explore how built up roofing compares to these other flat roofing systems commonly used in Arizona.

Built Up Roofing vs. TPO

TPO (Thermoplastic Polyolefin) is a single-ply roofing membrane that’s often marketed for its low cost and energy efficiency. While it’s become a popular option, especially in new commercial construction, there are trade-offs.

Feature Built Up Roofing TPO
Durability Up to 30 years with proper maintenance 15–25 years
UV Resistance High with reflective coating or gravel Excellent
Puncture Resistance High due to multiple layers Moderate
Seam Strength Hot-mopped or adhesive-sealed Heat-welded seams can fail under expansion stress
Installation Labor-intensive but time-tested Fast and inexpensive to install

TPO may be ideal for lighter structures or temporary installations, but for long-term commercial use, especially in buildings like schools, warehouses, or retail centers, built up roofing offers greater peace of mind.

Built Up Roofing vs. EPDM

EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber roofing membrane. It’s lightweight, flexible, and ideal for large, flat roofs with minimal penetrations.

However, it has some critical weaknesses in Arizona:

  • UV vulnerability: Unlike built up roofing, which resists degradation from the sun when surfaced with gravel or coating, EPDM can break down more quickly under Arizona’s intense UV radiation.

  • Shrinkage: Over time, EPDM tends to contract, pulling at seams and flashing—leading to leaks if not meticulously maintained.

While EPDM has its place, the built up roofing system is better suited to extreme heat and long-term use in cities like Buckeye, Sun City, and Queen Creek.

Built Up Roofing vs. Spray Foam (SPF)

SPF roofs are gaining popularity due to their seamless application and high R-value. They’re often touted for energy efficiency and ease of installation. However, they also come with strict application requirements.

  • Weather sensitivity: Spray foam must be applied during very specific weather conditions. A single windy or humid day can ruin an install.

  • Maintenance: The foam surface is easily damaged by foot traffic or hail and requires regular re-coating every 5–10 years.

Built up roofing, by contrast, can endure decades with standard maintenance and offers better resilience against foot traffic and physical impacts.

If you’re considering SPF, talk to our specialists about commercial roof coatings and compare them directly to BUR systems before making a decision.

For more technical comparisons, GAF’s commercial roofing insights provide a helpful overview of materials.

Why Built Up Roofing Makes Sense in Arizona’s Climate

Here’s the deal—Arizona is not a “one-roof-fits-all” region. Between the intense UV index, monsoons, dust storms, and hail in cities like Avondale and Anthem, you need a roofing system that’s time-tested under pressure.

That’s where built up roofing continues to outperform. Its thickness, layering, and fire-resistant materials offer:

  • Greater protection against wind uplift (important during monsoons)

  • Enhanced leak resistance even if the surface coating is damaged

  • Thermal mass that reduces temperature swings, making your building more stable and energy efficient

This is especially helpful for industrial and retail spaces with HVAC systems on the roof, which can further strain lightweight membranes like TPO.

Looking for expert guidance? Whether you’re in Tempe, Peoria, or Surprise, our team of commercial roofers can help you weigh your options with real-world insights from over a decade of regional experience.

Maintaining Built Up Roofing: Inspection & Repair Strategies for Long-Term Performance

One of the primary reasons so many commercial building owners across Phoenix, Tempe, and Scottsdale continue to choose built up roofing is its exceptional durability. But even the toughest roofing system isn’t completely immune to damage from time, weather, or neglect.

Proper maintenance of your built up roofing system isn’t just a good idea—it’s essential for maximizing its lifespan, maintaining energy efficiency, and avoiding costly repairs down the road.

How Often Should Built Up Roofing Be Inspected?

Industry standards, including recommendations from the National Roofing Contractors Association (NRCA), suggest that commercial roofs be professionally inspected at least twice per year—once in the spring and once in the fall.

However, in Arizona’s extreme climate, we recommend an additional post-monsoon inspection in cities like Glendale, Goodyear, and Cave Creek. The intense winds and flash floods of monsoon season can loosen gravel, damage flashing, and compromise drains or scuppers.

If your building experiences hailstorms—common in Anthem or Sun City West—you’ll also want to request an immediate inspection to check for membrane punctures or blistering.

Learn more about monsoon-related roof hazards here.

What to Look For During Built Up Roofing Inspections

During a professional inspection of your built up roofing system, your roofer should check for:

  • Surface cracks or alligatoring in asphalt layers

  • Blistering caused by trapped moisture or air

  • Ponding water near drains or low-pitch areas

  • Loose or bare gravel that exposes the bitumen below

  • Damaged flashing around HVAC units, skylights, or parapets

  • Signs of UV degradation on exposed membrane areas

At Castile Roofing, our commercial roof inspection teams in Peoria, Buckeye, and Tolleson use infrared moisture detection to identify subsurface damage invisible to the naked eye.

When Should You Repair or Replace a Built Up Roofing System?

Built up roofing is known to last 20–30 years or more, but that’s assuming timely repairs are made when needed. Minor issues like small punctures or isolated blisters can often be patched with a compatible mastic or reinforced membrane.

But if you’re seeing systemic problems—like widespread leaking, sagging, or visible deterioration—it may be time to consider partial or full replacement. Our commercial roofing experts can help you determine whether a restoration coating will suffice or if a tear-off is the better investment.

Want to stay ahead of expensive damage? Check out this in-depth maintenance guide by Buildings.com on commercial flat roofing upkeep.

Proactive Tips to Extend the Life of Your Built Up Roofing

To make the most of your investment in built up roofing, follow these maintenance best practices:

  • Keep the surface clean: Remove debris after storms, especially leaves and branches that can clog drains.

  • Maintain drainage systems: Ensure scuppers, downspouts, and internal drains are free of blockage.

  • Limit foot traffic: Use designated walk paths and install protective mats near HVAC service points.

  • Schedule seasonal maintenance: Especially critical before and after Arizona monsoons.

  • Apply reflective coating: Helps reduce thermal stress, improve UV resistance, and lower cooling costs.

For added longevity and energy efficiency, some commercial owners in Verado and Casa Grande have chosen to top-coat their built up roofing systems with elastomeric or silicone coatings. Our roof coating team can help evaluate compatibility and recommend the right material for your system.

Tax Incentives, Energy Rebates & Insurance Considerations for Built Up Roofing

Installing built up roofing on your commercial property isn’t just a structural upgrade—it can also provide real financial benefits when it comes to tax incentives, insurance premiums, and energy savings.

Many Arizona property owners in Tempe, Surprise, and Avondale have found that built up roofing contributes not only to long-term durability, but also to eligibility for key deductions and rebates that can significantly lower total project cost.

Depreciation Benefits Under IRS Section 179

Thanks to the IRS Section 179 Deduction, eligible business owners can write off qualifying roofing improvements—such as built up roofing installation or full replacement—in the year the expense is incurred, rather than spreading it over decades.

This deduction, designed to encourage business investment, has become a major financial driver for Arizona commercial owners investing in new roofing systems. For roofs that don’t require structural expansion, BUR replacements often qualify.

You can read more directly from the IRS Section 179 FAQ.

To find out whether your upgrade qualifies, it’s also wise to consult a tax advisor familiar with Arizona commercial building codes and federal depreciation rules.

Utility Rebates & Cool Roofing Programs

Another benefit of built up roofing—especially when topped with a reflective white coating—is its ability to qualify for utility rebate programs offered by power providers like Salt River Project (SRP) or Arizona Public Service (APS).

For example:

  • APS Cool Roof Rebates offer commercial customers incentives for reflective roofing materials that meet ENERGY STAR® standards.

  • Some Maricopa County municipalities provide green building bonuses for roofing systems that reduce heat island effect.

Applying a UV-resistant coating over your built up roofing in areas like Phoenix or Mesa can reduce roof temperatures by up to 60°F, cutting HVAC loads and slashing summer energy bills.

Visit EnergyStar.gov to explore qualifying roof coatings and BUR-compatible materials.

How Built Up Roofing Impacts Insurance Ratings

From an insurance standpoint, built up roofing is considered a high-resilience option for flat commercial structures. The multiple layers of bitumen and reinforcing fabrics are valued by many commercial underwriters for their:

  • Fire resistance

  • Wind uplift protection

  • Waterproofing durability

  • Impact resistance (especially with gravel-surfaced systems)

Insurers operating in monsoon-prone areas like Goodyear or Buckeye may offer reduced premiums for roofs that meet or exceed FM Global or UL Class A fire ratings.

Some insurers also prefer built up roofing because it can be easily patched rather than requiring full section replacements—translating to faster and less expensive claims.

To see if your existing commercial coverage aligns with your roofing system, consult this guide from the Insurance Information Institute.

Documentation That Helps Maximize Financial Benefits

If you’re planning to install or replace built up roofing, make sure your contractor provides detailed documentation, including:

  • Manufacturer material certifications

  • Warranty coverage on coatings or membranes

  • Photos of project milestones

  • Final inspection reports and code compliance confirmations

At Castile Roofing, we provide comprehensive closeout packages to assist our clients with tax prep, rebate applications, and insurance updates. Whether you’re in Queen Creek, Tolleson, or Casa Grande, we’re here to make your investment in built up roofing count—financially and structurally.

Built Up Roofing Installation: What Arizona Businesses Should Expect

When properly installed, built up roofing provides decades of protection for flat and low-slope commercial structures. But successful installation requires knowledge, precision, and adaptation to the Arizona climate. At Castile Roofing, we’ve executed BUR installations in urban zones like Phoenix and Glendale as well as suburban hubs like New River and Anthem—and the key to long-term success always lies in the installation process.

Step 1: Surface Preparation & Deck Inspection

Every built up roofing installation begins with a full tear-off (if replacing an existing roof) or a substrate evaluation (if starting fresh). Our crew inspects the decking for rot, rust, and structural damage. Any issues are addressed immediately.

Surface preparation includes:

  • Power brooming or vacuuming dust and debris

  • Removing moisture via drying techniques if needed

  • Ensuring the deck meets code for slope and fastening

This stage is especially critical in monsoon-sensitive areas like Casa Grande or Sun City, where water intrusion from undetected substrate issues could spell disaster.

Step 2: Base Sheet Installation

The first layer of the BUR system is typically a mechanically fastened or cold-adhered base sheet. This layer acts as a stable foundation for the rest of the system and helps improve fire resistance and wind uplift performance.

Options for base sheets include:

  • Asphalt-impregnated fiberglass

  • Organic felt with asphalt adhesives

  • Torch-applied modified bitumen base layers

Our residential roof repair crews use similar materials in some cases, but commercial built up roofing requires higher fire ratings and heavier weight tolerances.

Step 3: Multiple Ply Layers of Felt or Fiberglass

After the base layer is secure, we begin applying multiple plies of asphalt-saturated felt or fiberglass, embedding each layer into hot asphalt as we go. This layering—often three to five plies deep—gives built up roofing its name and provides unbeatable waterproofing and structural redundancy.

Each layer is:

  • Rolled out in a staggered configuration

  • Adhered using hot mopped asphalt or cold process adhesives

  • Smoothed to eliminate air pockets or bridging

In Glendale or Tempe, where roof temperatures often exceed 150°F in summer, these layers help prevent blistering and UV fatigue over time.

Step 4: Protective Surfacing

The final component is the surface coating, which protects the membrane from weather and mechanical wear. BUR systems can be finished with:

  • Gravel (aggregate) embedded in asphalt

  • Reflective coatings (acrylic, aluminum, or elastomeric)

  • Mineral-surfaced cap sheets for a clean finish

Reflective surfacing not only extends the roof’s life—it also qualifies for energy efficiency rebates in cities like Mesa and Scottsdale. For a list of coatings that meet ENERGY STAR® standards, visit Cool Roof Rating Council.

Optional Additions: Tapered Insulation & Skylight Integration

Many of our commercial clients opt to enhance their built up roofing systems with:

  • Tapered polyiso insulation, to encourage drainage

  • Walk pads, for maintenance access

  • Skylight flashing systems, for daylighting benefits

Whether you’re outfitting a warehouse in Avondale or an office park in Verado, we tailor every BUR system to meet your building’s needs and your city’s code requirements.

Built Up Roofing Requires Experience—Castile Roofing Delivers It

The installation of built up roofing is a complex, multi-day process that should never be rushed or assigned to inexperienced crews. Improper asphalt temperatures, poor ply adhesion, or skipped surface prep can lead to early failures, leaks, and voided warranties.

That’s why commercial clients across Maricopa County—from Queen Creek to Surprise—continue to choose Castile Roofing. With over a decade of expertise and a deep understanding of the regional climate, we install BUR systems that stand the test of time, weather, and budget.