A polycarbonate dock door panel exists so that a forklift driver and a dock supervisor can see each other without opening the door. That makes it a safety device, and it has to survive the traffic that makes it necessary.
A distribution centre in Rotterdam replaced 24 door windows after a run of failures. Every cracked panel was in a bay where the door was hit by a reversing trailer, and every crack started at a corner where the frame clamped the sheet hard.
Polycarbonate dock door panel specification
- Standard window: 6 mm, 400 x 600 mm
- High-traffic bay: 8 to 10 mm
- Corner radius: 10 mm minimum, never square
- Frame: gasketed, 2 mm clearance, no hard clamp
Square corners in a moving door are stress concentrators. A 10 mm radius spreads the load and doubles the life of the panel in a door that racks as it travels.
Gaskets, condensation and cleaning
The gasket does two jobs: it seals the weather out and it isolates the panel from the door frame. An EPDM gasket on both faces, with the panel free to move a millimetre, is the detail that stops cracking.
Condensation is the visibility problem. A single pane between a warm warehouse and a freezing yard fogs on the warm face and ices on the cold one. A sealed unit with a desiccant spacer, or a low-wattage heater in the frame, keeps the window usable through winter.
Cleaning happens with whatever the yard crew has. Alkaline degreasers attack polycarbonate at stressed edges, and a panel cleaned weekly with a strong detergent will craze within a year. Warm water and a neutral detergent is the instruction to put on the door.
Where the dock also has fixed glazing in the wall, the specification overlaps with polycarbonate security glazing, and the scratch and coating question is covered in polycarbonate scratch resistance.
Send your door type, panel size and traffic pattern to oversales@rpplexiglass.com for a vision panel quote.
Frequently Asked Questions
What thickness polycarbonate for a dock door vision panel?
6 mm for a standard 400 x 600 mm window in a roller door, 8 mm to 10 mm where forklift masts or pallets come close. Impact is the driver, not the size.
Why do dock door windows crack?
Rigid clamping in a door that flexes. Roller doors move and a hard frame concentrates stress at the corner. A gasketed frame with 2 mm clearance and rounded corners removes most failures.
How do you stop condensation in a cold dock door?
A sealed unit or a heated frame. A single pane in a door between a warm warehouse and a cold yard fogs every time the door cycles, and in winter it ices.