The polycarbonate vs steel debate isn’t simply about cost or appearance—it encompasses strength considerations, weight implications, weather resistance, and specific application requirements that can significantly impact your project’s success. Understanding these fundamental differences is essential for making an informed decision.
In this guide, we’ll break down the critical factors that should influence your decision, providing clear comparisons backed by real-world examples from our portfolio of completed projects.
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Understanding the Materials
What is Polycarbonate?
Polycarbonate is a thermoplastic polymer characterized by exceptional impact resistance and optical clarity. Made from carbonic acid diester and bisphenol A, this versatile material comes in various forms for roofing applications, including multi-wall sheets, corrugated panels, and solid sheets of different thicknesses.
Modern polycarbonate roofing typically includes UV-protective coatings and can be manufactured with various cell structures that trap air for improved insulation properties. The material’s clarity can range from transparent to tinted or opaque, depending on project requirements.
What makes polycarbonate valuable is its combination of lightness and strength. Unlike glass, which shatters upon impact, polycarbonate absorbs energy and resists breaking—making it particularly valuable in areas prone to hail or falling debris.
What is Steel in Roofing?
Steel roofing represents one of the most established materials in the construction industry. In roofing applications, we typically work with several varieties:
- Galvanized steel: Steel coated with a layer of zinc for corrosion resistance
- Galvalume steel: Coated with an aluminum-zinc alloy offering superior corrosion protection
- Stainless steel: Contains chromium for exceptional rust resistance but at a premium price
Modern steel roofing panels feature protective polymer coatings that add color options and additional weather protection. These coatings have dramatically improved in recent decades, with warranty periods extending to 30+ years for premium products.
The material’s versatility allows for numerous profile options—from standing seam designs that minimize visible fasteners to corrugated panels that maximize strength-to-weight ratios.
Strength and Durability Comparison
Polycarbonate Strength Properties
Polycarbonate’s most impressive quality is its impact resistance—it’s approximately 200 times stronger than glass and significantly more shatter-resistant than acrylic. This means polycarbonate roofing can withstand hailstorms that would damage many other materials.
Typical polycarbonate roofing exhibits tensile strength between 9,500-10,500 psi (pounds per square inch), which is remarkable considering its lightweight nature. However, its load-bearing capacity is generally lower than steel, requiring more frequent supports in the underlying structure.
We recently completed a project for a garden center where impact resistance was critical due to frequent hailstorms. The 16mm multi-wall polycarbonate has successfully weathered several severe storms without damage.
Steel Strength Properties
Steel roofing stands as an industry benchmark for structural integrity. With tensile strength typically ranging from 30,000-80,000 psi (depending on the specific alloy), steel significantly outperforms polycarbonate in load-bearing applications.
Wind resistance is another area where steel excels. Properly installed steel roofing systems can withstand wind speeds exceeding 140 mph when correctly fastened. This superior strength allows for wider purlin spacing in the supporting structure, potentially reducing overall construction costs.
For a commercial facility near the coast, the standing seam steel roof system we installed was tested to withstand Category 4 hurricane winds—a level of protection that polycarbonate simply cannot match.
Comparative Analysis
| Property | Polycarbonate | Steel |
|---|---|---|
| Impact Resistance | Excellent (virtually unbreakable) | Good (may dent) |
| Tensile Strength | 9,500-10,500 psi | 30,000-80,000 psi |
| Load-Bearing Capacity | Moderate (requires more supports) | Excellent (wider spans possible) |
| Wind Resistance | Moderate (properly fastened) | Excellent (140+ mph) |
| Flexibility | High (can be cold-formed on site) | Limited (pre-formed) |
For structures where heavy snow loads or extreme winds are expected, steel generally provides superior performance. However, for applications where impact resistance and lightweight properties are paramount, polycarbonate offers unique advantages.
Weight Considerations in Construction
Weight Specifications
The weight difference between these materials is substantial:
- Polycarbonate roofing typically weighs between 0.25-0.8 pounds per square foot
- Steel roofing generally weighs between 1.0-3.0 pounds per square foot
This difference might seem negligible on paper, but across a large roofing area, it translates to tons of additional weight. For a 5,000 square foot commercial roof, choosing steel over polycarbonate could add 5,000-10,000 pounds of load to the structural system.
Structural Implications
The lightweight nature of polycarbonate creates several advantages. Structures supporting polycarbonate roofing can often be designed with lighter framing members, potentially reducing overall building costs. This becomes particularly important in retrofit applications where the existing structure has limited load-bearing capacity.
In a recent renovation project, the client wanted to replace an aging fiberglass skylight system. Using steel would have required significant reinforcement of the existing supports. The polycarbonate solution saved approximately $28,000 in structural modifications while providing superior light transmission.
Transportation and Installation Factors
The weight difference substantially impacts handling during installation. Polycarbonate panels can typically be managed by one or two installers, while steel panels often require mechanical assistance or larger crews.
Installation efficiency also differs significantly. Our crews can typically install polycarbonate roofing 15-25% faster than comparable steel systems, primarily due to easier handling and simpler cutting requirements. For time-sensitive projects, this efficiency can translate to meaningful schedule advantages.
Weather Resistance and Durability
UV and Weather Exposure
Modern polycarbonate roofing materials include UV-protective layers that prevent yellowing and degradation. However, these protective features eventually break down, typically limiting the effective lifespan to 15-20 years before significant deterioration occurs.
Steel roofing, when properly coated and maintained, demonstrates exceptional weather resistance. Premium steel roofing systems can maintain their appearance and function for 40-50+ years, with minimal signs of deterioration even after three decades of service.
Corrosion Resistance Properties
Polycarbonate is inherently immune to rust and corrosion, making it ideal for highly corrosive environments like coastal areas or industrial zones with high pollution levels.
Steel’s corrosion resistance depends entirely on its protective coatings. Once these barriers are compromised—through scratches, poor installation practices, or weathering—corrosion can begin quickly. Galvanized steel installations in coastal environments may show signs of corrosion within 5-7 years without proper maintenance, while inland installations might remain pristine for decades.
In a waterfront restaurant project where we installed both materials, after eight years, the polycarbonate portions remained virtually unchanged, while the steel sections required maintenance to address early signs of corrosion despite having premium coatings.
Expected Lifespan
With proper installation and maintenance, typical lifespans for these materials are:
- Polycarbonate: 15-20 years
- Steel: 30-50+ years for premium systems
This lifespan difference should be factored into any long-term cost analysis.
Cost Analysis
Initial Material Costs
The upfront cost difference between these materials varies:
- Polycarbonate: $3.50-$8.00 per square foot for material only
- Steel: $4.00-$12.00+ per square foot for material only
These ranges reflect variation based on thickness, coating quality, and specialized features. Multi-wall polycarbonate with advanced heat-blocking properties might cost twice as much as basic twin-wall options. Premium steel with specialized finishes can cost three times more than entry-level steel roofing.
Installation Expenses
Installation costs also differ:
- Polycarbonate installation: $2.00-$4.00 per square foot
- Steel installation: $3.00-$7.00 per square foot
Steel typically requires specialized cutting equipment, more labor for handling heavier materials, and often more complex fastening systems. Polycarbonate can generally be cut on-site with standard tools and requires less specialized labor.
In a recent commercial project, the polycarbonate section required 82 labor-hours for completion, while the comparable steel section required 126 labor-hours—a difference of approximately 43%.
Long-term Maintenance Costs
Maintenance requirements create another cost differential:
- Polycarbonate typically requires cleaning and inspection every 1-2 years
- Steel generally requires inspection and potential touch-up every 3-5 years
Over a 30-year period, maintenance costs for polycarbonate approximate 15-25% of the initial installation cost, while steel maintenance typically ranges from 10-20% of the initial cost.
ROI Calculation
When calculating return on investment, consider:
- Initial installation cost (materials + labor)
- Expected maintenance costs over planned ownership period
- Potential energy impacts (heating/cooling)
- Expected lifespan and replacement timing
- Potential insurance impacts (some policies offer discounts for impact-resistant materials)
For a typical 30-year analysis period, steel generally offers a better ROI despite higher initial costs, primarily due to its longer lifespan. However, where light transmission or weight savings are valuable, the calculation may favor polycarbonate.
Specific Applications
Residential Roofing Considerations
In residential applications, aesthetic considerations often take precedence alongside performance requirements. Steel roofing has seen tremendous growth in the residential sector, with modern profiles mimicking traditional materials like slate or shake while offering superior performance.
Polycarbonate in residential applications is typically limited to specific features—sunrooms, covered patios, or skylight systems where light transmission is desirable. We recently completed a covered deck using multiwall polycarbonate that provides weather protection while maintaining the bright, open feel the homeowner desired.
Steel roofing can be significantly louder during rain or hail events, though proper underlayment and insulation can mitigate this issue. Polycarbonate tends to provide better acoustic performance without additional treatments.
Commercial Applications
For commercial structures, longevity and maintenance requirements often drive material selection. The initial cost premium for steel is frequently justified by its extended lifespan and reduced maintenance requirements. Steel’s superior fire resistance can result in insurance advantages for commercial properties.
Polycarbonate finds its commercial niche in applications where light transmission offers functional benefits, such as atriums, walkway covers, and recreational facilities.
Greenhouse and Specialty Structures
Polycarbonate allows approximately 80-90% light transmission while providing diffused light that reduces plant stress and shadows. Its insulating properties—particularly in twin or triple-wall configurations—can reduce heating costs by 30-40% compared to single-layer materials.
Steel, while inappropriate for the main greenhouse covering, often serves as the structural framework supporting polycarbonate panels. This combination leverages the structural strength of steel with the light-transmitting properties of polycarbonate.
In a commercial growing facility, a galvanized steel framework supporting a multi-wall polycarbonate envelope has maintained consistent growing conditions despite extreme temperature fluctuations outside.
Safety Applications
Polycarbonate’s virtually unbreakable nature makes it excellent for impact-prone areas or regions with severe weather events. Its lighter weight also reduces injury risk during installation and presents less danger in the event of structural failure.
Steel provides superior fire resistance—a critical consideration for many commercial and public structures. It won’t ignite, burn, or support combustion, potentially containing a fire rather than contributing to its spread.
Environmental Considerations
Manufacturing Impact
The environmental footprints of these materials differ:
- Polycarbonate production is energy-intensive and petroleum-based, with a higher carbon footprint per pound
- Steel production requires significant energy, but modern recycling practices have reduced its overall environmental impact
Polycarbonate’s lighter weight can reduce shipping emissions compared to steel, partially offsetting its higher production impact for distant projects.
Recyclability
End-of-life considerations influence material selection:
- Steel is almost infinitely recyclable without quality degradation and has well-established recycling channels
- Polycarbonate is technically recyclable, but practical recycling options remain limited in many regions
We’ve established partnerships with recycling facilities that allow us to divert nearly 94% of our steel removal waste from landfills, but fewer practical options exist for polycarbonate recycling.
Energy Efficiency
Thermal performance impacts a building’s ongoing environmental footprint:
- Multi-wall polycarbonate provides insulation values typically ranging from R-1.6 to R-4.0
- Steel offers minimal insulation (approximately R-0), requiring additional materials for comparable thermal performance
For naturally lit spaces, polycarbonate’s combination of light transmission and insulation can reduce both heating and artificial lighting requirements.
Frequently Asked Questions
Is polycarbonate stronger than steel?
No, steel possesses significantly higher tensile strength than polycarbonate (30,000-80,000 psi compared to polycarbonate’s 9,500-10,500 psi). However, polycarbonate offers superior impact resistance and can absorb impacts that would dent steel panels. Steel excels in structural applications where load-bearing capacity is critical, while polycarbonate performs better in situations requiring impact absorption.
Which costs more: polycarbonate or steel roofing?
The initial material cost comparison shows steel roofing typically costing 10-30% more than comparable polycarbonate options. However, when considering the entire lifecycle, steel often represents the better value due to its significantly longer lifespan (30-50+ years vs. 15-20 years for polycarbonate). Installation costs also tend to be higher for steel.
Can polycarbonate roofing withstand heavy snow loads like steel can?
Polycarbonate has lower load-bearing capacity than steel and generally requires more frequent structural supports when used in snow-prone regions. For heavy snow applications, we typically recommend either steel or a reinforced structural system if polycarbonate is preferred for other reasons (such as light transmission).
How does polycarbonate compare to steel for electronics enclosures?
For electronics enclosures, polycarbonate offers several advantages: electrical insulation properties, transparency options for monitoring equipment, and lighter weight for portable applications. Steel enclosures provide superior EMI/RFI shielding, better heat dissipation, and greater security.
Is bulletproof polycarbonate as strong as steel?
Specialized bulletproof polycarbonate (typically much thicker than roofing grades) can stop certain bullets, but it functions differently than steel armor. Polycarbonate absorbs and disperses impact energy, while steel primarily blocks penetration through hardness. For ballistic protection, polycarbonate typically requires 1.5-3x the thickness of steel to achieve similar protection levels.
Which requires more maintenance: polycarbonate or steel roofing?
Polycarbonate typically requires more frequent maintenance, including regular cleaning to maintain light transmission and inspection of seals and fasteners every 1-2 years. Steel requires less frequent but potentially more intensive maintenance, with inspection recommended every 3-5 years and occasional repainting or coating repair needed over its lifespan.
Which material is better for greenhouse construction?
Polycarbonate is generally superior for greenhouse applications due to its light transmission properties (80-90%), diffusion characteristics that reduce plant stress, and insulating properties that maintain more stable growing conditions. Steel serves excellently as the structural framework supporting polycarbonate panels.
How long does polycarbonate roofing last compared to steel?
With proper installation and maintenance, polycarbonate roofing typically lasts 15-20 years before requiring replacement, while premium steel roofing systems can last 30-50+ years. Environmental factors like UV exposure, pollution levels, and proximity to saltwater can significantly impact these expected lifespans.
Can polycarbonate and steel be used together in roofing projects?
Yes, we frequently design hybrid systems that combine both materials to leverage their complementary strengths. Common applications include steel roofing with polycarbonate skylights, covered walkways with steel structural elements supporting polycarbonate panels, and greenhouse structures with steel framing and polycarbonate covering.
Which material performs better in extreme temperatures?
Steel maintains its structural integrity across a wider temperature range (-50°F to 200°F+ without significant property changes) compared to polycarbonate, which becomes increasingly brittle at extremely low temperatures and may soften at very high temperatures. However, polycarbonate provides better insulating properties, potentially creating more stable interior conditions despite external temperature extremes.
Conclusion
The polycarbonate vs steel decision depends on your specific project requirements, budget considerations, and performance priorities. Through our decades of experience with both materials at Regan Roofing, we’ve found that neither represents a universal “best choice”—each offers distinct advantages for particular applications.
For projects prioritizing structural strength, longevity, and fire resistance, steel typically represents the superior option despite its higher initial cost. The material’s proven track record in demanding applications and minimal maintenance requirements often justify the premium investment over the structure’s lifetime.
Conversely, applications benefiting from light transmission, impact resistance, and lightweight properties often favor polycarbonate solutions. The material’s versatility and clarity create possibilities that aren’t achievable with opaque materials like steel.
Many successful projects incorporate both materials, strategically leveraging their complementary properties. This integrated approach often delivers the best overall value and performance, particularly for complex structures with diverse requirements.
Whatever your specific needs, our team at Regan Roofing Inc. can help you navigate the polycarbonate vs steel decision with confidence. Contact our expert consultants to discuss your specific project requirements and discover the ideal roofing solution for your unique situation.
