and roof support elements fig2 shows narrow roof end 300 that has a flat section on top that creates a section of roof and from that roof section extends a section that has the same cross sectional dimensions as the connectors so that the piece can be placed into a cavity 15 or two cavity 17 s fig2 shows roof center 310 that is used when a wall or corner cavity is not available roof corner 320 is shown in fig2 that has features for use over corner pieces said features include extensions that fit into cavities 15 or 17 are arranged at 90 degrees with respect each other fig2 shows wide roof end 330 that has two extensions for cavities 15 or 17 and smaller extensions that fit into the vertical cavities of the roof extensions fig2 shows an exploded assembly view of a possible configuration for a roof assembly the roof support elements and connectors create beams that extend from wall to wall and are attached to said walls with connectors the roof elements are placed to that one continuous surface exists over the area bounded by the walls and corner sections in the preferred embodiment the parts shown in the preceding figures are made of plastic further the preferred manufacturing process for said parts is plastic injection molding fig2 shows plastic injection mold 400 that is a possible configuration of a device that can be used to create a short wall section referring now to fig2 a possible shipping and storage configuration is shown one of the advantages of the invention is that it can be stored and shipped easily in the preferred embodiment a box like shipping container.