Most structures meant for human habitation are permanent and securely fixed to their sites. There are temporary structures such as tents and gazebos that can be taken down and moved, but these are not designed for long term use. Prefabricated buildings are known and are becoming more popular, but once erected, these are usually intended to be fixed to their sites and made permanent.
A review of rigid structures that can be moved reveals very limited examples which are for relatively small structures designed to cover or enclose a hot tub. Reville, in U.S. Pat. No. 6,604,327 teaches a retractable trackless spa enclosure made up of two sections, both constructed of an extruded aluminum frame, clear plastic side panels and Gambrel roof. One section is slightly smaller than the other and has a back wall. The larger front section slides over the smaller back section to nest around the back section. A pivotally mounted front wall tilts to enable the front section to move over the spa. Both sections can be moved away from the spa during good weather and can completely enclose the spa during inclement weather. This system can work well for hot tubs of varying sizes but would not work for a full sized swimming pool or for a large patio area. In U.S. Pat. No. 6,374,433, Gray discloses a movable hot tub cover structure that includes four walls and a roof. The cover structure sits on a wheeled cart which moves on high density plastic or rubber wheels over angle iron rails. The cover structure is moved by means of a garage door reversible motor activated by a remote control and utilizes a chain drive located on each transverse side. The hot tub is located at ground level and the cover structure is situated on a raised deck built contiguous with the upper level of the hot tub. The cover structure can completely cover the hot tub or be completely removed from the hot tub. The patent describes the walls as being from three to seven feet high and the sides from ten to thirty feet long. This structure may work well for covering a hot tub, but would not be practical to cover a large outdoor area. If the system described and illustrated were to be thirty feet long it would have to be constructed of a very light plastic.
Structures have been designed to cover full sized swimming pools and these range from fabric covered steel frames to permanent structures, often having one or more walls of windows or sliding doors that can be opened in good weather and closed during inclement weather. Other means have been developed to cover swimming pools, but these do not represent structures, merely covering means. See U.S. Pat. No. 4,815,152 to Mac Donald et al. An interesting permanent pool covering structure is taught by Nohl et al. in U.S. Pat. No. 4,598,506. There is a movable floor supported by four upright columns. The floor can be lowered forming a usable floor space that completely covers the pool, and can be raised to form a second ceiling when the pool is to be used.
There is a need for a rigid structure that can completely enclose an outdoor area such as a swimming pool during inclement or cold weather while being movable to the extent that the outdoor area is completely uncovered and exposed during warm weather. There is a need for a structure that, though quite large, can be moved easily, either to cover the desired area or uncover it, without the need for cumbersome machinery or complex systems. There is a need for such a movable structure for home and recreational use as well as for use in commercial settings.