Trailer manufacturers are constantly looking for ways to improve durability, appearance, and long-term performance without increasing weight. For decades, aluminum trailer siding has been the standard material used on cargo trailers, toy haulers, and specialty vehicles.
While aluminum and cheap alternative composite materials offer a lightweight solution for trailer exterior panels, it also comes with a well-known drawback: oil canning. Many trailer manufacturers are now exploring composite trailer siding panels as an alternative to traditional aluminum trailer siding, particularly for cargo trailers and enclosed trailers.
Piedmont Plastics developed PolyCor™ AP to solve this problem. PolyCor AP is a specially engineered composite trailer siding panel designed for enclosed trailers, cargo trailers, and specialty vehicle applications. For trailer manufacturers looking for durable cargo trailer siding panels, PolyCor AP provides a lightweight and stable alternative to traditional aluminum trailer siding.
Even more importantly, PolyCor products are available exclusively through Piedmont Plastics, ensuring manufacturers receive consistent, high-quality material rather than lower-quality alternatives. In this guide, we’ll explore what PolyCor AP is, why it was developed, how it compares to aluminum trailer siding, and why sourcing authentic PolyCor from Piedmont Plastics matters.
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An Introduction to PolyCor AP
PolyCor AP is a high-performance composite siding material developed and distributed exclusively by Piedmont Plastics as a superior alternative to traditional aluminum trailer panels. Unlike aluminum sheets, PolyCor AP is structurally designed to resist oil canning, even in extreme temperatures. The result is a trailer exterior that maintains a smooth, flat, professional appearance throughout its lifespan.
Key Characteristics of PolyCor AP
Resistance to oil canning
Lightweight with strong structural stability
Waterproof, resistant to salt and chemicals, and easy to clean.
Noise reduction during transport
Backside primer for improved adhesion
No galvanic corrosion concerns
Strong thermal insulation properties
Common PolyCor AP Applications
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Exterior Siding Panels
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Interior Wall Panels
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Trailer Ceilings
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Cabinet Surfaces
Why PolyCor AP Performs Better
Although aluminum has long been used for trailer exterior panels, PolyCor AP delivers clear performance advantages for manufacturers of cargo trailers and enclosed trailers. In addition, as cheap composite alternatives enter the market and fall short of expectations, PolyCor AP continues to set the standard for durability and reliability.
Oil Canning Resistance: The most significant advantage of PolyCor AP is its resistance to oil canning. The material’s structural stability prevents the warping and distortion commonly seen with aluminum siding, even in environments with extreme temperature changes. This ensures trailers maintain a smooth exterior surface that supports clean graphics and professional branding.
Lightweight and Structurally Stabile: Weight plays an important role in trailer performance and towing efficiency. PolyCor AP is lightweight, helping improve towing and allowing for greater payload capacity. At the same time, it offers excellent rigidity, helping trailer wall panels maintain their shape and reduce movement during transport.
Waterproof and Chemically Resistant: Moisture can damage cargo and shorten the lifespan of a trailer. PolyCor AP panels are completely waterproof, helping protect the interior and improve long-term durability. They also offer strong chemical resistance, making them well suited for environments where exposure to oils, cleaners, or other substances is common.
Reduced Road Noise: Composite trailer siding materials can also help reduce vibration and road noise. PolyCor AP’s construction dampens sound during transport, resulting in a quieter trailer while traveling.
Easy to Clean and Maintain: PolyCor AP features a durable polyester paint coating that can be cleaned with standard household products. Its smooth surface is ideal for graphics, wraps, and branding, helping trailers maintain a clean, professional look over time.
What is Oil Canning?
The Problem with Oil Canning on Trailers
For trailer manufacturers and dealers, oil canning distortions on trailer siding can lead to several problems:
Unprofessional appearance: Wavy panels reduce the visual quality of the trailer
Distorted graphics or branding: Commercial graphics can appear uneven or warped
Panel instability over time: Constant movement can affect the structural integrity of the siding
Inconsistent surfaces: Difficult to maintain a smooth finish across large trailer panels
From hot summer highways to freezing winter storage conditions, trailers are constantly exposed to temperature fluctuations that cause aluminum to move. PolyCor AP trailer siding panels are engineered to prevent this issue.
Unlike aluminum sheets, PolyCor AP maintains structural stability across temperature changes, helping trailers retain a smooth, flat exterior surface throughout their service life. PolyCor AP panels also feature a durable polyester paint system that supports simple installation, long-term durability, and easy maintenance.
Why Trailer Manufacturers Are Switching To PolyCor
Piedmont Plastics supports trailer manufacturers at every stage of the process, from material selection and fabrication guidance to installation support and ongoing customer service. Our team works closely with manufacturers to ensure they’re using the right product for their specific applications. PolyCor AP is also backed by a warranty, providing added peace of mind that many lower-quality alternatives simply do not offer.
“We're in the business of helping you find new products for existing applications that will outperform conventional materials. That's the PolyCor story.”
Proven Performance and Reliability
PolyCor AP has proven itself as a trusted material in the trailer industry. As one of the first materials of its kind brought to market, it has been used in the production of over 150,000 trailers. It offers full lot traceability for quality assurance, has demonstrated durability with over 3,000 hours of ASTM B117 salt spray testing without degradation, and is manufactured with strict on-site quality control standards. In addition, PolyCor AP is UL certified for use with low voltage wiring, further supporting its reliability in modern trailer applications.
Limitations of Aluminum Trailer Siding
Many manufacturers are making the switch from aluminum trailer siding to PolyCor AP due to the long-term performance challenges associated with metal panels. Aluminum is prone to oil canning, which creates visible waves in trailer siding over time and can distort graphics and branding. It also expands and contracts with temperature changes, leading to inconsistent surfaces and potential durability concerns. In addition, 0.050" aluminum is 25% heavier than PolyCor AP, which averages 0.58 lbs/ft2 per sheet. While aluminum has been widely used for years, these drawbacks have pushed manufacturers to seek more stable and reliable composite trailer siding solutions.
PolyCor AP vs. Aluminum
For decades, aluminum trailer siding panels have been the industry standard for cargo trailers and enclosed trailers. However, composite materials like PolyCor AP offer several performance advantages.
| Feature | PolyCor AP Trailer Siding | Aluminum Trailer Siding |
|---|---|---|
| Oil Canning Resistance | Engineered to resist oil canning | Prone to oil canning |
| Weight | Slightly lighter than .040 aluminum | Depends on thickness |
| Structural Stability | High stability | Can flex and distort |
| Waterproof | Completely waterproof | Water resistant |
| Chemical Resistance | Excellent | Moderate |
| Surface Appearance | Smooth, flat exterior | May develop waves |
| Noise Reduction | Helps dampen road noise | Metal may amplify vibration |
| Corrosion | No galvanic corrosion | Potential corrosion |
If It's Not Piedmont, It's Not PolyCor
PolyCor AP is part of the PolyCor™ product family, a line of materials developed and supplied exclusively by Piedmont Plastics. This exclusivity offers several advantages:
Quality assurance with consistent material performance
Reliable supply through Piedmont’s North American distribution network
Technical expertise from specialists familiar with trailer manufacturing applications
Protection from imitation materials and low-quality replicas
While PolyCor AP is optimized for exterior trailer siding panels, other PolyCor materials may be used for interior wall panels, trailer ceilings, cabinet surfaces, and flooring systems. Together, these materials help manufacturers build trailers using high-performance plastic solutions designed for durability and long-term appearance.
Beware of Knock-Off Composite Trailer Siding
Piedmont Plastics is the exclusive distributor of PolyCor AP.
As demand for composite trailer siding panels continues to grow, some dealers in the industry may be unaware of, or even misrepresent, the difference between genuine PolyCor AP and lower-quality alternatives. To avoid confusion, it’s important to ask your dealer or manufacturer a simple question: Is this trailer built with PolyCor AP from Piedmont Plastics?
While imitation materials may look similar at first glance, they often lack the engineering, consistency, and quality control required for demanding trailer applications. Lower-cost composite panels can introduce a range of performance issues that impact both appearance and durability over time.
Common Issues with Imitation Composite Materials:
- Lower structural stability
- Poor performance in extreme temperatures
- Surface imperfections and inconsistent finishes
- Reduced impact resistance
- Inconsistent coatings or protective layers
- Faster long-term degradation
Frequently Asked Questions About PolyCor AP
Have questions about PolyCor AP and how it compares to alternative trailer siding materials? Below are answers to some of the most common questions from trailer manufacturers and buyers.
PolyCor AP is a composite trailer siding panel developed exclusivly by Piedmont Plastics as an alternative to traditional aluminum trailer siding.
Oil canning occurs when trailer siding expands and contracts due to temperature changes, creating visible waves in the trailer exterior. Products like PolyCor AP do not oil can.
No. PolyCor AP is specifically engineered for trailer siding to reduce oil canning while maintaining a smooth, clean appearance. It also offers a strong balance of rigidity, impact resistance, and long-term durability. Other composite panels often lack the consistent performance and application-specific design that PolyCor AP delivers.
Yes. PolyCor AP is slightly lighter than .040 aluminum siding and significantly lighter than .050 aluminum panels.
PolyCor AP is widely used across cargo trailers, enclosed trailers, toy haulers, utility trailers, and livestock trailers. Its versatility also makes it a strong solution for a range of applications beyond the trailer industry.
Yes. The polyester paint finish allows the panels to be cleaned using standard household cleaning products.
PolyCor AP has many color options. PolyCor AP standard colors include white, grey, black, and silver. PolyCor AP vibrant color options include red, blue, indigo, yellow, orange, green, brushed aluminum, champagne, saharah desert, and brandywine. Additional custom color options are also available.
PolyCor AP is available exclusively from Piedmont Plastics.
Upgrade Your Trailer Siding with PolyCor AP
Traditional aluminum siding has long been used for cargo trailer walls and exterior trailer panels, but modern composite materials like PolyCor AP provide clear advantages. With resistance to oil canning, improved durability, lightweight construction, and a smooth professional finish, PolyCor AP helps manufacturers build trailers that perform better and maintain their appearance over time.
Because PolyCor products are available exclusively through Piedmont Plastics, manufacturers can trust they are receiving high-quality material engineered specifically for trailer applications. Contact us to learn more about PolyCor AP composite trailer siding or request a quote for your cargo trailer or specialty vehicle project!
