A rail element is provided having a longitudinal axis, a first longitudinal end and a second longitudinal end longitudinally spaced from the first end along the longitudinal axis. The rail element includes a rail body longitudinally extending between the first longitudinal end and the second longitudinal end, the rail body defining therein at least one longitudinally extending first lumen having a longitudinally co-extensive transverse first opening, the rail element being configured for being mounted to at least one longitudinal support member in load bearing contact therewith in operation of the rail element. The rail element is configured for being mounted to the at least one longitudinal support member in a non-longitudinal manner A system for covering an area incorporating such rail elements is also provided, as well as a method for using such a system.

A portable and retractable roof having a rotatably retractable cover housed inside a case and attached to a spindle rotatably housed inside the case. The case is removably affixed to a tree trunk by a tree mount disposed as a frame attached to the case and attached to the trunk by a strap. The cover, when extended, is attached to and supported by a frame assembly attached to both the cover and to either the case or the tree mount. A skirt portion removably affixed to the frame assembly is also provided. In use, the cover is rotatably extended out so as to serve as a roof and rotatably retracted to store in the case. A method of use is also provided.