Inside/outside loading docks require doors at each dock position to keep the inside environment separated from the outside when there is no a truck at the dock. Usually these doors are opened only once for each truck and kept open during loading. For this reason, manually operated overhead sectional or rolling doors are the most common. Sectional doors have rollers which run inside tracks are smoother and quieter. Also they are thicker and stronger against wind and impact as compared with rolling doors; and can be insulated. If the doors ride in tracks, the tracks should be protected with concrete filled pipes.
Door widths are commonly 2.4 m and their heights an commonly 2.4, 2.7, or 3.0. Dimensions of the door are determined by the typical trucks, the desired seal or shelter, and the plant environmental needs. If clear access to the entire trailer width and height is required, the door must extend about 4.2 m above the driveway and be at least 2.5 m wide.
To maintain effective control of refrigerated operations with foam pad seals, usually you need to use doors narrower than 2.4 m. For refrigerated facilities, also specify insulated dock doors.