The weakest point of a cold room is the door: when it opens, warm humid air flows in and cold air flows out; even when closed, the gasket and frame leak heat. The door leaf is made with the same foam as the panels, 60–150 mm thick, with two or three rows of flexible gasket around it; in frozen rooms a heating element is laid in the frame so that the gasket does not ice up and the door does not stick.
Types: hinged door (small to medium rooms, 0.8–1.2 m wide, an inside safety release handle is mandatory), sliding door (large openings, forklift traffic, 1.5–3 m), swing (clear PVC) door (positive rooms with very frequent passage, inside the main door), high-speed roll-up door (heavy forklift traffic, opens and closes in seconds) and dock doors (truck docking). By temperature there are "chilled room" (0 °C) and "frozen room" (−20 °C, thick and heated) versions.
Door opening is a significant item in the heat load calculation: at the door of a distribution warehouse that opens hundreds of times a day, air infiltration can reach a third of the total load; an air curtain, PVC strip curtain and automatic closing reduce it. The cooling load calculator takes door usage intensity (light / normal / heavy) as an input.