Mechanical lock: 2-inch structural
2-Inch Mechanical Lock Standing Seam for Metal Buildings and Open Framing
The 2-inch mechanical lock standing seam is our structural panel. The PMRS sheet says it was designed for pre-engineered metal buildings and calls the single-lock panel the industry’s most extensively tested, with over 50 years of field history. It spans open framing and comes in the widest range of metals we form.
- 20+ years of experience
- Lifetime limited warranty
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2-inch mechanical lock specifications
The data below is drawn from the PMRS 2″ Structural and Architectural Mechanically Seamed Panel System sheet.
| Property | 2″ mechanical lock |
|---|---|
| Seam height and lock | 2″; folded by power seamer to 45, 90 or 180 degrees |
| Coverage | Variable, 12″ to 18″ |
| Rating | Heavy duty and structural, for residential and commercial work |
| Pitch | 1/2:12 or steeper |
| Support | Open framing or a solid deck |
| Clip system | Heavy-duty interlock clip that secures the panel and lets it expand and contract |
| Tested assemblies | Seam sealant is required when air and water tests are specified |
| Steel gauges | 22, 24 or 26 |
| Aluminum | .040″ or .032″ |
| Copper | 20 oz or 16 oz |
| Zinc | Rheinzink in .8 or .7 mm |
| Coil-coater finish terms | 30-year Kynar 500 or Hylar 5000 solids; 20-year metallics; 15-year SMP; 25-year steel warranty on Galvalume Plus |
| Typical uses | Metal buildings, commercial roofs over purlins, long spans and heavy-gauge architectural work |
The PMRS 2″ mechanical lock spec sheet (PDF) includes the profile and seam drawings. The resort on its cover is a manufacturer photo, not a PMRS project.
What sets the 2-inch apart from the 1-inch and 1.5-inch?
It is built as structure, not just skin. The 1″ and 1.5″ mechanical locks need a solid deck. The 2″ can span open framing, held by a heavy-duty interlock clip that secures the panel while letting it expand and contract.
It also has the most options. Within our mechanical lock standing seam line, it is the only panel with a 45-degree seam, 22-gauge steel, .040″ aluminum and 20 oz copper.
There are tradeoffs. Widths stop at 18″, the tall seam reads bold on a small house, and its sheet does not list the 35-year ULTRA-Cool finish shown for the smaller panels.
Which seam should you choose: 45, 90 or 180 degrees?
Each further fold adds resistance to wind and water, plus a little seaming time. We match the lock to the project specification.
- 45 degrees: a partial fold, offered only on the 2″ panel, used where the specification calls for it
- 90 degrees: a single lock, the classic upright seam for pitched roofs
- 180 degrees: a double lock, our choice for low slopes and high uplift
Whatever the angle, seam sealant goes inside the seam when the project calls for air and water testing.
Where does the 2-inch mechanical lock belong?
Choose it when the roof must carry load across framing, or when the specification calls for heavier material.
- Pre-engineered metal buildings, shops and warehouses with purlin framing
- Schools, churches and commercial roofs with long, low-slope spans
- Barndominiums and large outbuildings that deserve concealed fasteners instead of exposed screws
- Architectural roofs in 20 oz copper, Rheinzink zinc or 22-gauge steel
On a typical house, the 1.5″ mechanical lock gives the same low-slope rating with a lighter look. For a budget metal building, compare our corrugated and exposed-fastener panels.
How do we install the 2-inch panel in North Texas?
Engineering comes first on open framing. Clip spacing over purlins depends on span, gauge and wind exposure, so we work from the project engineering or provide site-specific engineering on request.
- Over purlins: heavy-duty interlock clips fastened to each framing member at the specified spacing
- Over a deck: high-temperature underlayment rated for a North Texas summer under the panels
- Seams folded with a power seamer to the specified angle, with sealant where testing applies
- Trim, closures and gutters formed to match the roof
That clip and seam combination earns its keep here. In May 2024, a DFW storm brought gusts near 80 mph along with baseball-size hail.
Metal-building and commercial roofs are quoted from drawings. Homeowners can budget from $15 per square foot, our installed standing seam rate, and test options in the roof cost calculator.
2-inch mechanical lock questions
Can the 2-inch mechanical lock go directly over purlins?
Yes. The PMRS sheet lists it for a solid deck or open framing. Clip spacing over purlins comes from the project engineering, which we can provide on request.
Is the 2-inch panel too bold for a house?
On a small house it can look heavy. On a large or modern home with long, low roofs, the tall seam reads clean. Compare the drawings on the 1.5″ sheet and the 2″ sheet before you choose.
What does the 45-degree seam option do?
It is a partial fold, the lightest of the three locks on the 2″ panel. The 90 and 180-degree locks fold further for more resistance to wind and water, so we match the seam to the project specification.
Can the 2-inch panel be made in copper or zinc?
Yes. It is formed in 16 or 20 oz copper and in .7 or .8 mm Rheinzink zinc, the widest metal range in our line. See our warranties page for coverage details.
Get Your Free Metal Roof Estimate
Tell us about your roof and a Permanent Metal Roofing Systems specialist will follow up to schedule your free estimate. No pressure, no obligation.
Prefer to talk now? Call (469) 466-2421.
Roofing a metal building or a long-span structure?
Send us the drawings and framing layout. We will confirm clips, seam and gauge, and we can supply shop drawings and submittals.