138T & 238T Metal Roofing Systems: Strength, Style & Superior Commercial & Residential Performance

Discover the unmatched strength, style, and flexibility of McElroy Metal's 138T and 238T standing seam systems.

In today's construction industry, choosing the right roofing system isn't just about what looks good or what holds up—it's about finding a product that does both. Architects, contractors, and property owners demand solutions that are as tough as they are beautiful. And that's exactly where our 138T and 238T standing seam panels come in.

These two flagship systems are proof that form and function can coexist seamlessly. Designed to withstand the elements while enhancing a building's architectural profile, both the 138T and 238T panels offer long-term performance with unmistakable curb appeal. Whether you're working on a new commercial development, retrofitting an older metal roof, or upgrading a residential property, these panels provide a smart, stylish, and sustainable solution.

In this post, we'll take a deep dive into the features, benefits, and real-world applications of these symmetrical standing seam systems, exploring why they're becoming the go-to choice for forward-thinking builders and building owners.

Understanding 138T and 238T Standing Seam Panel Systems

At first glance, the 138T and 238T panels might seem like just another pair of standing seam metal roofing options. But a closer look reveals innovative design features that make them stand out.

ror images of each other. This design not only enhances aesthetics with sleek, uninterrupted lines but also delivers long-term value through simplified installation and maintenance.

Here's a quick breakdown of the differences:

138T Panel:

• Rib height: 1 3/8 inches
• Panel width: 16 inches
• Substrate: Galvalume® steel or optional aluminum
• Install over: Solid decking only

238T Panel:

• Rib height: 2 3/8 inches
• Panel widths: 12", 16", 18", or 24"
• Substrate: Galvalume® steel or optional aluminum
• Install over: Open framing or solid decking

Explore more standing seam metal roofing options or see our guide to selecting panels: How to Choose the Best Metal Roofing Panel.

Both panels are available in a wide array of premium finishes, including PVDF coatings like Kynar 500® that are engineered to resist fading and chalking for decades. So whether you're going bold with a striking color or staying classic with a neutral tone, your roof will look as good in 30 years as it does today.

The Advantages of Symmetrical Standing Seam Design

Not all standing seam panels are created equal, and symmetrical design is one of those subtle but game-changing features that set the 138T and 238T apart.

Unlike traditional double-lock or snap-lock systems, symmetrical panels are easier to repair and modify. That's because individual panels can be removed and replaced without disturbing the neighboring ones—a huge advantage for roofs expected to last 40–60+ years.

As Charlie Smith, National Recover Manager at McElroy Metal, puts it:

"There are many reasons why symmetrical standing seam panels are better than double lock or snap panels. First, they are more waterproof because they do not have any interruptions in the seam sealant when they are installed. They are site-formed when the panels are too long to ship, which eliminates potential leaks at end laps. Second, they have very high wind uplift resistance. Third—and most importantly—they are easy to repair or alter after they are installed. You have a roof that should last 60-plus years; it would be nice to be able to make a simple repair."

That simplicity in repair and the enhanced watertightness of symmetrical designs give building owners peace of mind, knowing that future maintenance won't be a major headache or expense.

Standing Seam Panel Comparison: 138T vs 238T vs Medallion-Lok

When it comes to standing seam roofing, McElroy Metal offers several high-performing options, but selecting the right panel depends on the priorities of your project.

Our 138T and 238T panels are mechanically seamed systems designed for the most demanding commercial and architectural applications. These panels shine on jobs that require long panel runs, on-site rollforming, high wind uplift, or recover solutions. With weathertightness warranties available and proven performance in retrofit scenarios, they're engineered for durability and serious structural performance.

Medallion-Lok, on the other hand, is a snap-lock system that delivers a crisp architectural look without the need for seaming equipment. It's a favorite for architectural roofing projects and commercial buildings where appearance and ease of installation matter most. While it may not offer the same structural recover capabilities as 138T and 238T, it's ideal for new construction or reroofing where aesthetics and straightforward installation are priorities.

Metal Roofing Applications and Use Cases

The versatility of the 138T and 238T panels makes them an ideal fit across a wide variety of building types. Whether you're constructing something new or looking to breathe new life into an older structure, these panels adapt to the needs of nearly any project.

Common Applications Include:

Commercial buildings: Shopping centers, warehouses, office parks, and industrial plants benefit from the strength and low maintenance of metal panels, while architects appreciate the modern, streamlined aesthetic. See our solutions by building type.

Residential properties: For homeowners seeking durability and elevated curb appeal, these panels offer superior protection from extreme weather while enhancing the architectural beauty of the home. Explore residential metal roofing.

Post-frame and agricultural buildings: Think barns, equipment sheds, and livestock shelters—where performance and longevity are essential. Learn more about post-frame solutions.

Institutional facilities: Schools, hospitals, government centers, and churches also benefit from the combination of strength, low maintenance, and energy efficiency.

Even in high-slope or low-slope scenarios, there's a solution:

• The 138T panel is approved for slopes as low as 2:12.
• The 238T panel can be used on slopes as low as ½:12 when approved, making it ideal for flat or nearly flat roofs that require superior drainage and weather protection.

Performance Testing and Wind Uplift Resistance

When it comes to performance, the numbers speak for themselves. Both the 138T and 238T have undergone rigorous testing to ensure they exceed industry standards. These panels meet or exceed:

• UL 580 for uplift resistance
• UL 1897 for static pressure
• ASTM E1592 for structural performance
• ASTM E1646 and E1680 for water and air infiltration

In real-world terms, this means the panels are designed to withstand:

• High winds (including hurricane-force gusts)
• Heavy rainfall and snow loads
• Thermal expansion and contraction

The mechanically seamed ribs and floating clip systems allow the panels to expand and contract with temperature changes without causing stress on fasteners or seams, helping to reduce oil-canning and extend system life.

Metal Roof Recover Systems: Retrofit Solutions

Replacing an entire roof system is a major investment—and a major disruption. That's why McElroy Metal developed recover solutions using the 138T and 238T panels. These systems allow contractors to install new roofs directly over existing ones, saving both time and money.

Two Key Recover Options:

138T Shingle Recover System: Designed for light commercial and residential reroofing projects, this approach uses a patented clip that creates an energy-saving airspace between the old and new roof. It enhances ventilation, reduces thermal transfer, and eliminates the need for expensive tear-off. Learn more: Installing a Standing Seam Metal Roof Over Shingles.

238T Metal-Over-Metal Recover System: Perfect for older metal roofs nearing the end of their lifecycle, this system includes structural framing members that support the new panel system. Explore the system: 238T Metal-Over-Metal Recover and our overall Retrofit & Recover resources.

Installation Requirements and Best Practices

Both systems are built for long-term success, but they require skilled installation to achieve their full potential.

Key Installation Considerations:

Mechanical Seaming: The panels are secured with mechanical seamers, ensuring a tight, consistent lock. McElroy Metal offers seaming machine rentals, onsite roll forming, and installer training.

Substrate Requirements:

• 138T panels must be installed over solid decking (e.g., plywood or metal deck with insulation).
• 238T panels offer more flexibility and can be used over either open framing or solid substrates.

Complete System: Matching trims, ridge caps, closures, and accessories are available to ensure a weather-tight, architecturally consistent roof system.

Support Materials: Access installation manuals, CAD drawings, spec sheets, and more in our Product Information & Downloads center.

Sustainability and Metal Roof Longevity

Metal roofs aren't just a smart investment—they're a sustainable one too. The 138T and 238T systems are made from recycled steel and are 100% recyclable at the end of their service life. Additionally, McElroy's reflective cool roof coatings help reduce energy usage, especially in warm climates, by reflecting more of the sun's rays and keeping buildings cooler.

With proper installation and routine inspections, these systems can last 40 to 60 years, or more. Unlike traditional asphalt shingles that may need replacement every 15 to 20 years, a standing seam metal roof offers decades of protection with minimal upkeep.

Professional Testimonials and Real-World Performance

It's one thing to hear about performance on paper—it's another to hear it from those in the field.

David F., a commercial contractor in the Gulf Coast region, shared this:

"The 238T system is a game-changer. We needed a panel that could handle the Gulf Coast's punishing winds and rain… the architectural look made the school board and the design team happy. It was the best of both worlds—function and form in one solution."

Contractors appreciate the ease of installation, designers love the sleek profile, and owners benefit from lower energy costs and fewer repair calls over the lifespan of the roof.

Product Video

If you're looking for a roofing solution that won't force you to choose between beauty and performance, McElroy Metal's 138T and 238T standing seam systems are well worth a closer look.

From residential rooftops to retail facilities, schools, and government buildings, these panels deliver consistent, high-performance results. Their symmetrical design provides simplified repair, while their long lifespan, sustainability, and range of finish options make them a practical yet visually impressive solution.

Frequently Asked Questions

What is the difference between the 138T and 238T standing seam systems?

The 138T and 238T panels share a symmetrical design but have different dimensions and installation requirements. The 138T panel has a 1 3/8" rib height and is installed over solid decking, while the 238T panel has a 2 3/8" rib height and can be installed over open framing or solid decking.

Why choose a symmetrical standing seam design?

Symmetrical standing seam panels provide superior watertightness and wind uplift resistance compared to traditional systems. They are also easier to repair because individual panels can be removed and replaced without disturbing adjacent ones. Learn more about our standing seam roofing options.

What applications are best suited for 138T and 238T panels?

These panels are versatile and can be used on commercial, residential, post-frame, and institutional buildings. From shopping centers and schools to barns and homes, they adapt to nearly any project.

Can 138T and 238T panels be used for low-slope roofing?

Yes. The 138T panel is approved for slopes as low as 2:12, while the 238T panel can be used on slopes as low as ½:12 when approved, making it ideal for low-slope and flat roof applications.

How long do these metal roof systems last?

With proper installation and maintenance, the 138T and 238T systems can last 40 to 60 years or more, offering significantly longer service life compared to traditional asphalt shingles. Learn more about residential metal roofing longevity.

What are the recover options available with these panels?

McElroy Metal offers two primary recover systems: the 138T Shingle Recover System, designed for reroofing over asphalt shingles, and the 238T Metal-Over-Metal Recover System, which installs directly over older metal roofs with structural framing support. See all our Retrofit & Recover solutions.

Are these systems energy efficient and sustainable?

Yes. Both panels are made from recycled steel and are 100% recyclable at the end of their service life. Additionally, McElroy’s reflective Cool Roof Coatings help reduce energy costs by reflecting sunlight and lowering heat gain.

Do 138T and 238T systems require special installation equipment?

Yes. Both panels are mechanically seamed and require a seamer for installation. McElroy Metal provides standing seam services, including seamer rentals, onsite roll forming, and installer training resources.

What warranties are available?

Weather-tightness warranties are available for projects using the 138T and 238T systems. Explore more about McElroy Metal warranties.