A roll-up door including thermal protection devices provided in the mounting arrangement thereof to prevent the transfer of cold outside air, snow, ice and the like through the doorway covered by the roll-up door, the thermal protection devices including a plastic member in the mounting arrangement to provide a thermal break therein, heating members also disposed in the mounting arrangement, and a heated hood disposed over the support roller on which the door is rolled up into in the opened position thereof. The plastic member can have a snap-on construction to facilitate the assembling thereof, and also for the removal thereof in the event replacement is necessary. The roll-up door is provided with a direct drive gearing arrangement disposed between the motor gear of the roll-up and roll-down mechanism and the support roller gear to avoid the building up of forces therethrough usually caused when the support roller becomes fixed in place or difficult to rotate due to cold weather conditions. Preferably, the mounting arrangement also includes a wind bar and weather sealing fins to prevent outside wind, rain, snow and the like from passing therethrough into the doorway.