Polycarbonate cold storage glazing is specified for two reasons: it does not shatter when a pallet truck clips a door, and it can be built into an insulated panel without a heavy frame. The rest of the design is about heat and moisture.
A frozen food distributor in Rotterdam replaced 12 door windows after a series of failures. Panels had cracked at the frame and every window iced over within a shift. The cause was a single-pane 6 mm sheet in a minus 28 C room.
Polycarbonate cold storage glazing options
- 16 mm twinwall: U-value around 1.6 W/m2K, small viewing windows
- 25 mm multiwall: U-value around 1.0 W/m2K, larger apertures
- 8 mm to 10 mm solid: impact-led specification, small windows
- Low-temperature grade: mandatory below minus 20 C
The U-value is the operating cost argument. A single 6 mm pane has a U-value near 5.8 W/m2K and will condensate on the warm side every time the door is closed. Multiwall at 25 mm cuts that by a factor of five.
Condensation, heaters and frame detail
A freezer window fogs because warm humid air in the shop meets the cold panel. Two accepted answers: a sealed unit with a desiccant and a warm-edge spacer, or a heated frame with a low-wattage element. Thicker single glazing does not solve it.
The frame must be insulated and thermal-broken. A steel frame in a freezer room becomes a cold bridge, and the window ices from the edge inward. A thermally broken frame with a gasket on both sides is the standard detail.
Hygiene is the second specification. Food facilities clean with alkaline or chlorinated agents, and polycarbonate has limits. The polycarbonate chemical resistance guide sets out what is safe, and the PC sheet weight guide helps with the door load calculation.
Where the room also needs strip curtains or a viewing panel at a loading dock, the design overlaps with polycarbonate security glazing.
Send your door model, room temperature and hygiene regime to oversales@rpplexiglass.com for a glazing recommendation.
Frequently Asked Questions
What polycarbonate for a cold storage door window?
Multiwall polycarbonate of 16 mm to 25 mm where a U-value matters, or 8 mm to 10 mm solid sheet where the window is small and impact resistance dominates. Both must be low-temperature grades for rooms below minus 20 C.
Why do freezer windows fog on the inside?
Warm moist air meeting a cold surface. The fix is a sealed double-glazed unit with a desiccant, or a heated frame, not a thicker single pane. A single pane in a freezer door will fog and then ice.
Does polycarbonate get brittle in a freezer?
Standard grades lose impact strength at low temperature. Specify a low-temperature or high-impact grade for rooms below minus 20 C, and test a sample at service temperature before approving.