Architectural metal: flat lock
Flat Lock Metal Panels for Turrets, Curves, Mansards and Walls
Flat lock metal panels are small, flat pans of copper, zinc or aluminum with all four edges folded so each one hooks into its neighbors. With no raised seam, they follow curves and tight shapes that standing seam cannot, from turrets and eyebrow dormers to mansards and feature walls.
- 20+ years of experience
- Lifetime limited warranty
- Free written estimates
What are flat lock metal panels?
They are a traditional way of cladding roofs and walls in sheet metal. Each pan is cut to size, and opposite edges are hemmed in opposite directions. The pans then interlock on every side, and concealed cleats hold them to the substrate.
Laid in staggered courses, the pans form a flat, tiled surface with fine shadow lines instead of tall ribs. Because each piece is small, the system can bend around a cone, a curve or a compound shape.
Flat lock is one of the architectural panels in our standing seam metal roofing range. PMRS has no published spec sheet for it, so the values below are typical and confirmed per project.
| Specification | Flat lock panels |
|---|---|
| Material | Copper (16 or 20 oz typical), .7 or .8 mm Rheinzink zinc, or painted aluminum |
| Profile | Flat pans with folded, interlocking edges on all four sides |
| Coverage | Pan size laid out to the surface: smaller pans for curves, larger for flat walls |
| Attachment | Concealed cleats; no exposed fasteners |
| Finish | Natural copper or zinc patina; PVDF (Kynar 500) colors on aluminum |
| Impact, wind and fire ratings | No published PMRS rating for this profile; assembly data on request |
| Minimum slope | Steep slopes and walls when unsoldered; low slopes need soldered flat seams |
| Warranty | Coil-coater finish warranty on painted aluminum; ask how our lifetime limited warranty applies |
| Best for | Turrets, cupolas, curved bays, eyebrow dormers, mansards and accent walls |
Where do flat lock panels fit on DFW homes and buildings?
On the details that define a facade. These are the places we see flat lock earn its cost.
- Turrets and round towers on Tudor, Victorian and French-style homes
- Curved bay roofs, eyebrow dormers and entry canopies
- Mansards and accent walls on retail, office and multifamily buildings
- Chimney and parapet cladding that should match a copper or zinc roof
Hail
Copper and zinc are soft metals, so large hail can leave dents. Flat lock usually goes on walls and steep, sheltered surfaces, where exposure is lower than on a main roof plane. Ask us about heavier material on exposed areas.
Heat
Small pans move less individually than long panels, and the folded joints absorb some thermal movement. That helps in a region that typically sees about 20 days a year at or above 100 F.
HOAs
A copper or zinc accent is still a material change, so it needs approval. We supply samples and drawings for your architectural committee.
How does PMRS fabricate and install flat lock?
Fabrication is where flat lock succeeds or fails, because every pan has to match. We cut and fold pans on the same computerized equipment we use for trim, so hems and dimensions repeat exactly.
- Substrate: solid sheathing, checked smooth, because flat pans show every bump
- Underlayment: high-temperature underlayment suited to metal in Texas heat, with a separation layer where the metal calls for one
- Layout: courses set out from a reference line, so joints stagger evenly around curves
- Pans: each one hooked into the course below and fastened with concealed cleats
- Transitions: flashing to standing seam, walls and windows formed from the same metal
What colors and natural finishes are available?
Fresh copper is bright and salmon-toned. It mellows to brown over time and greens only slowly in a dry climate. Rheinzink starts a soft gray and weathers evenly.
Painted aluminum takes PVDF colors from our metal roof color chart. That lets a flat lock turret match a painted standing seam roof.
Flat lock, diamond panels or standing seam?
Let the shape of the surface decide. The table compares the three.
| Feature | Flat lock | Diamond panels | Standing seam |
|---|---|---|---|
| Look | Flat, tiled courses with fine lines | Diagonal diamond pattern | Long vertical ribs |
| Curves and cones | Handles them very well | Handles them well | Limited; curved panels need special forming |
| Typical surfaces | Turrets, walls, mansards, bays | Turrets, dormers, steeples, accent walls | Main roofs and walls |
| Piece size | Small pans | Small squares set on point | Panels run the full slope |
| Low-slope option | Soldered flat seam | None | Mechanical lock to 1/2:12 |
For pattern and texture, see our diamond metal roof panels. For the main roof, mechanical lock standing seam pairs naturally with copper or zinc flat lock. Flat lock is quoted per project; our metal roof cost page covers whole-roof budgets.
Flat lock panel questions
What is the difference between flat lock and flat seam?
The terms overlap. Flat lock usually means unsoldered interlocking pans for steep slopes and walls. Flat seam often means the same pans with soldered joints, which lets copper or zinc work on low slopes.
Can flat lock metal panels go on a low-slope roof?
Only with soldered seams, which is specialist copper or zinc work. Unsoldered flat lock belongs on steep slopes and walls. For a low-slope roof in painted metal, our 1″ mechanical lock is rated to 1/2:12.
How much do flat lock panels cost?
They are quoted per project. Material, pan size and the shape of the surface drive the price, and curved work takes more labor than a flat wall. Send drawings or photos for a written quote.
Will copper flat lock stain my brick or stone?
Runoff from copper can leave green-blue streaks on light masonry below it. We plan drip edges and gutters to steer water away from stone and brick where the design allows.
Do you sell flat lock pans to contractors?
Yes. We can fabricate pans, cleats and matching flashing as a materials package, with shop drawings for commercial work.
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.
Have a turret, curve or feature wall to clad?
Send us drawings or photos. We will suggest a metal and pan layout, then quote the work in writing.