Abstract: An expandable transportable enclosure is described which includes an environmentally protected expandable section. The expandable section extends away from the body of the enclosure and includes an inflatable seal which fills the gap located between the expandable section and the body of the enclosure. The environmentally protected expandable section also includes a retractable floor which is raised off the bottom of the expandable section to insulate the floorboard from the exposed, bottom surface of the expanded section. Finally, an automatically retracting cover, over the expandable section, is provided to prevent the accumulation of snow, water, dirt, or other environmental elements on the top of the expandable section. The environmentally protected unit thus provides a comfortable and weather insulated expanded, interior trailer space without the requirement of costly manufacturing.