A polycarbonate cold storage door fails at the frame, not at the panel. The maintenance log of a distribution centre in northern Poland recorded the same complaint eleven times in one winter: the cold store viewing windows iced over on the inside by mid-morning. The panels were sound, the frames were not.
Polycarbonate cold storage door: thickness by duty
Acrylic becomes brittle at low temperature and impact resistance falls sharply below minus 10 degrees Celsius. Polycarbonate keeps its ductility to about minus 40, which is the entire reason it dominates cold-room doors.
That advantage is wasted if the frame bridges heat. A steel frame in contact with a minus 20 interior and a plus 20 exterior becomes a condensation surface, and the panel fogs from the edge inward.
Thickness by duty
- Low traffic, chiller at 0 to 5 degrees: 6 to 8 mm single pane
- Freezer at minus 18 to minus 25: 8 to 10 mm, or twin-wall 16 mm
- High traffic with trolley impact: 10 mm with a protective bumper
- Large windows above 1.2 m span: twin-wall or a framed double unit
The twin-wall option is not only about insulation. Its structure separates the cold inner surface from the warm outer one, so condensation forms where it can drain rather than where it can be seen.
Frame and gasket detail
Three details decide whether a door stays clear: a thermal break in the frame, a gasket that seals on a warm face rather than a cold one, and a condensate path that leads water away from the panel.
A heated frame strip is the belt-and-braces option in very humid plants. It costs a small amount of energy and removes the maintenance call entirely.
Hardware loads at low temperature
Hinges and closers are sized for the door mass, and polycarbonate panels are light for their stiffness. The risk is not the panel but the fixing: a steel bolt through a cold panel contracts faster than the plastic, and after a hundred cycles the hole has grown.
Use isolated fixings with a plastic sleeve, and allow 1.5 mm clearance in the hole. The door will still close square and the panel will stop cracking at the corners.
Cleaning and the condensation cycle
Cold-room panels are usually washed down with the same detergents as the floor. Neutral products are fine; alkaline degreasers will craze polycarbonate over time, particularly at the frame line where stress is highest.
Wipe dry after washing. Water left on a cold panel freezes into a film that reads as fog and gets reported as a panel fault.
For doors that also need security performance, the security glazing note covers the laminate options, and for lead time planning the sheet lead time guide is the practical reference.
Send door sizes, operating temperature and traffic frequency to oversales@rpplexiglass.com for a panel and hardware specification.
Frequently Asked Questions
Does polycarbonate stay clear at freezer temperatures?
Yes, down to about minus 40 degrees Celsius it stays ductile rather than brittle, which is why it is preferred over acrylic for cold-room doors.
Why does a cold room door window fog up?
Condensation forms when the inner surface is below dew point. A twin-wall panel, a heated frame or a double-glazed unit with a dry air gap solves it; a single pane does not.
What thickness for a busy chiller door?
8 to 10 mm single pane for low traffic, twin-wall 16 to 20 mm where condensation control matters, and 10 mm where trolleys strike the panel.