Designed primarily for commercial projects, but widely used on larger, design-forward homes, Medallion-Lok offers crisp, narrow seams, concealed fasteners, and the refined profile architects love. And because it's part of McElroy Metal's standing seam family, it's backed by our commitment to long service life, premium coatings, and industry-leading testing.
In this blog, we'll walk through what Medallion-Lok is, who it's designed for, where it works best, how it installs, and how it compares to other standing seam options in our lineup. By the end, you'll know exactly whether this panel fits your next project.
What Is Medallion-Lok?
Medallion-Lok is a concealed-fastener, snap-together standing seam panel built to provide the clean, contemporary appearance many designers want today. While its look is unmistakably sleek, the strength behind the panel is equally impressive.
Panel Type and Appearance
- Standing seam profile with a clean, architecturally refined look.
- 1.75-inch rib height, giving the roof sharp vertical definition.
- Available coverage widths: 12", 16", and 18".
- The panel installs with no exposed fasteners.
Substrates
- Standard substrate: 24-gauge Galvalume®
- Optional upgrade: 22-gauge Galvalume® (Possible minimum order and longer lead times may apply)
- Optional: .032 aluminum (Possible minimum order and longer lead times may apply)
Premium Coating System
Medallion-Lok is available with the industry's best-in-class PVDF finish, Kynar 500®. This coating offers exceptional long-term resistance to:
- Fading
- Chalk
- UV exposure
- Coastal weathering
If you're designing for longevity and color stability, this finish is the gold standard.
Color Options
Medallion-Lok can be ordered in all of McElroy Metal's architectural PVDF finishes, including Matte Black, Copper Penny, Brite Red, Patina Green, Regal Blue, Ash Gray, Texas Silver Metallic, and many more.
Explore full color options on our Color Visualizer to mock up your project in real time.
Engineering, Strength, and Tested Performance
Medallion-Lok may be chosen for its appearance, but its engineering is what keeps it performing for decades. Every detail in the system supports long-term durability.
Tested & Approved Ratings
- UL 580 Uplift:
- Construction No. 255 (open framing)
- Construction No. 343 (over plywood)
- Construction No. 468 (over metal deck)
- UL 2218 Impact Resistance: Class 4
- ASTM E1592: Uplift testing for structural performance
- ASTM E1680: Air infiltration
- ASTM E1646: Water penetration
- Fire Rating: Class A
- Florida Product Approval
- Miami-Dade Approval
- ICC-ES Report ESL-1082
If your project needs documented compliance for high-wind regions, Medallion-Lok checks the boxes.
Minimum Roof Slope
- 3:12 minimum
Panel Construction
- Snap-together seam — no mechanical seamer required
- Fully concealed clips
- Compatible with:
- Solid decking
- Open framing
This makes Medallion-Lok a versatile option for both commercial structures and custom homes.
Factory Eave Notch
A factory eave notch can be ordered for a clean, finished transition at the eave, reducing field labor and improving appearance.
Where Medallion-Lok Works Best
Medallion-Lok is one of the most versatile architectural systems in our lineup. While it's built for commercial-grade performance, it's frequently selected for residential and specialty applications where aesthetics matter just as much as longevity.
Common Project Types
- Commercial buildings
- Office and retail centers
- Schools and municipal buildings
- High-end custom homes
- Porch roofs and architectural accents
- Multi-structure campuses where consistent design language matters
What Problems Does It Solve?
Medallion-Lok tackles several of the challenges that typically come with traditional roofing systems. Here's how:
- Eliminates exposed-fastener concerns: With no fasteners on the roof surface, there are fewer potential leak points and far less long-term maintenance.
- Delivers a clean, modern look: The narrow 1.75" seam gives buildings a refined, architectural appearance that many owners prefer, especially on custom homes and commercial projects.
- Performs in demanding environments: With strong uplift testing, impact resistance, and Florida/Miami-Dade approvals, it's a great fit for coastal, high-wind, or severe-weather regions.
- Provides consistent weather sealing: The factory-applied in-seam sealant speeds installation and can create a uniform seal, no skipped beads or uneven application like you can get with field-applied sealant.
- Reduces installation labor: The snap-together design helps installers work faster while maintaining proper seam engagement and weather tightness.
- Enhances long-term durability: Premium PVDF finishes help the panel keep its color and resist fading over time, even in harsh sunlight.
Underlayment, Trim, Installation, and Tools
Installing a concealed-fastener standing seam system requires attention to detail, and Medallion-Lok is designed to make that process as straightforward as possible with its snap-together seam and concealed clip system. To help ensure a smooth installation and long-term performance, here are the recommended underlayment and accessory considerations:
Recommended Underlayment Guidance
- Synthetic underlayments are generally recommended for durability and ease of installation.
- Ice-and-water protection is recommended in all hemmed conditions (such as eaves, valleys, and other areas prone to water backup).
- Breathable underlayments can be helpful in assemblies where moisture management is a concern.
Trim & Accessories
- All trim components are available in matching PVDF finishes
- Ridge caps, hips, eaves, valleys, and transitions are engineered to integrate cleanly
- Factory eave notch available (recommended for best appearance)
Installation Difficulty
Snap-together standing seam panels require:
- Precise clip placement
- Proper panel alignment
- Attention to flashing details
Tools Required
- Standard metal roofing tools
- Snips, hand seamer (for trim adjustments), brake
- Fastening tools for clips
- Safety gear for working at height
Sustainability, Energy Savings & Lifespan
Medallion-Lok contributes to long-term environmental performance thanks to its materials, finishes, and lifespan.
Recyclability
Metal roof panels are recyclable at the end of life, reducing landfill impact.
Cool Roof Benefits
PVDF finishes help maintain reflectivity over time, reducing cooling loads in warm climates when reflective colors are selected.
Service Life
While lifespan varies based on climate and maintenance, Medallion-Lok is built for multi-decade performance when properly installed and maintained.
Maintenance Expectations
- Annual inspection
- Clearing debris
- Checking flashings
- Washing in coastal or industrial environments
McElroy's "Operation and Maintenance Manual (Roofs)" provides complete guidance.
Specifications & Technical Downloads
All resources are available on the Medallion-Lok page, including:
- Product Data Sheet
- Installation Manual
- Maintenance Manual
- ICC-ES Report (ESL-1082)
- Load Tables
- Florida Product Approval / Miami-Dade NOA
- PDF and CAD details
- Color Charts
You may download these documents on our Medallion-Lok page.
What Contractors & Architects Are Saying
For our current project at "Catalpa Gardens" (pic below), I chose to submit McElroy's Medalion-Lok because McElroy has "Old McDonald Yellow" as a color option. Half of this building we're working on is being covered in this color which is semi-standard for McElroy. Any other manufacturer would have cost us a large amount of money for "a custom color". Also, because your facility in Illinois is downstate and has much lower taxes than Chicago, we saved a good amount of money on taxes.
So basically, the architect picks the profile, and we can usually choose the manufacturer. For our current project, McElroy had the best value. - Ryan Hill of Knickerboker Sheet Metal
How Medallion-Lok Compares to Other McElroy Standing Seam Products
| Product | Best Use Case | Strengths | Choose When You Need… |
|---|---|---|---|
| Medallion-Lok | Architectural roofs/walls | Sleek narrow seam, PVDF finishes, snap-together ease | Beauty + performance for commercial or custom residential |
| Maxima | High-end commercial & structural | Mechanically seamed, high uplift, long panel runs | Highest structural performance |
| Meridian | Residential/light commercial | Economical, snap-together concealed fastener | Budget-conscious with architectural appearance |
| 138T | Metal-over-metal and metal-over shingle recover system | Patented 138T Clip creates a structural airspace: minimizes tear-off | A recover solution that avoids removing the old roof while improving energy performance |
| 238T | Commercial/industrial recover systems | Stronger version of 138T; taller 2⅜" seam; high wind uplift | A structural recover system for commercial buildings needing extreme uplift performance |
FAQs
Can Medallion-Lok be installed over shingles?
Installation over shingles is not standard. The roof deck must be evaluated, and many projects require re-decking or installing an approved overlay system. Always check local codes and the installation manual.
Is Medallion-Lok approved for hurricane zones?
Yes. Medallion-Lok has UL 580 uplift approvals, UL 2218 Class 4 impact resistance, and Florida/Miami-Dade approvals. Always follow job-specific gauge and clip spacing requirements.
What paint system is available?
Medallion-Lok features Fluropon®/Kynar 500® PVDF paint—industry-leading for color retention, UV protection, and long-term appearance.
Does metal roofing attract lightning?
No. Lightning is influenced by structure height and location, not roofing material. Metal roofs are actually safer because they are non-combustible.
Ready to Get Started?
If you're designing a modern home, commercial project, or architectural structure that needs both performance and beauty, Medallion-Lok is an excellent fit.
Here's what you can do next:
- Request samples from McElroy Metal
- Explore your design in our Color Visualizer
- Download spec sheets, CAD files, and installation guides
When you're ready, McElroy Metal is here to help you build with confidence—one panel at a time.
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