slot 92 provided in the floor pieces 11 as shown in fig1 the bottom projection 90 may be shaped as a hook to be slid under the floor to provide a more secure connection and stable support for the brace 14 in fig1 the center post 13 is installed by inserting bottom protrusions 96 each through the elongated opening 40 of the nut receiving seat 36 of the floor and the elongated aperture 44 of the corresponding floor locking nut 30 and locked by turning the floor locking nut 30 in a manner similar to that shown in fig1 12 each center post 13 and the corresponding brace 14 may be further secured together for instance by fasteners or the like in one embodiment the brace 14 includes three side bumps 98 distributed along its edge facing the center post 13 which includes three corresponding indents aligned for receiving the side bumps 98 to be interlocked therewith as schematically shown in fig1 a for instance the side bumps 98 and indents may be connected together by a tight fit or an interference fit in fig2 a lower roof truss 100 is connected to the braces 14 prior to installing the roof.