Interlocking metal roofing: five screws per panel, none on the surface.
Every screw in a WeatherLok roof goes into the deck and then disappears under the next course. Here's how the lock works, why it matters in wind and rain, and what to ask any roofer who says "hidden fastener."
Screw. Overlap. Lock.
Three moves per panel, repeated up the roof. Once the course above is on, the screws below it are covered.
Screw it to the deck
Five screws per panel, driven straight into the roof deck. Direct to deck, no battens. The panel is fixed to the structure, not just to the panel next to it.
Overlap the row below
Each 53-inch (135 cm) panel overlaps the course beneath it by 3.5 inches (9 cm). The screws sit under that overlap, so the course above covers every one of them.
Interlock the next course
The next panel clips onto the course below and interlocks. What you see from the ground is stone and steel, not screw heads.
An exposed screw is a hole with a rubber washer on it.
Exposed-fastener metal roofing puts every screw head out in the sun, the ice and the wind, and asks a rubber washer to keep the water out for decades. An interlocking, hidden-fastener roof takes that whole problem off the surface. On a WeatherLok roof the screws sit under the next course, sealed watertight, and the panels are rated for 110 mph (177 km/h) wind (ASTM D3161) as one interlocked system.
You'll hear this called click-lock, T-lock, snap-lock or hidden-fastener roofing. Different names, same idea: the fastener is covered and the panels lock to each other. What separates one system from another is how many screws hold each panel to the deck and what the panel is made of. Ours is five, into 26-gauge steel. On a Canadian roof that spends half the year in freeze and thaw, the fasteners sit under the course above instead of out in it.
What "interlocking" means on the spec sheet.
Pulled from the WeatherLok system specifications. The full sheet, with weight and coverage, is in the documents library.
| Fastening | Interlocking hidden-fastener system, direct to deck |
|---|---|
| Fasteners | Five hidden screws per panel, covered by the next course. Zero exposed screws, sealed watertight. |
| Panel size | 53.13" x 16.93" (135 cm x 43 cm), 3.5" (9 cm) overlap, 19 panels per square |
| Material | 26-gauge stone-coated steel |
| Weight | 147 lbs (67 kg) per square, panels only |
| Wind rating | 110 mph (177 km/h), ASTM D3161 |
| Hail rating | Class 4 impact, UL 2218 |
| Fire rating | Class A, UL 790 |
| Goes over an existing roof | Installs over one or two layers of existing shingles. No tear-off, no disposal fees. |
Screw it down once. Keep it for 70 years.
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