A portable building is disclosed, having a wall section including a first upwardly extending support member, a second upwardly extending support member and a header supported by the first upwardly extending support member and the second upwardly extending support member, the header having a header channel. The wall section also includes a floor beam secured to the first upwardly extending support member and the second upwardly extending support member, the floor beam having a floor beam channel. Further, the wall section includes a plurality of wall panels, where each of the plurality of wall panels are removably retained within the header channel and the floor beam channel, such that each of the plurality of wall panels are slidable along the floor beam and the header while retained within the header channel and the floor beam channel. Each of the plurality of wall panels are configured to interlockingly engage an immediately adjacent wall panel and an exterior surface of each of the plurality of wall panels form a continuous exterior wall surface.

A stud rail system comprising at least one stud rail assembly. The at least one stud rail assembly comprises a plurality of rail portions, a plurality of cross portions, where a plurality of sets of support openings are formed in each of the plurality of the cross portions, a plurality of pin projections, where each rail portion supports at least one pin projection, a plurality of support assemblies, and a plurality of support projections, where each support projection is supported by one of the plurality of support assemblies. Each of the support projections extends through one of the support openings in each set of support openings such that the rail portions are rotatably connected to cross portions at a plurality of axis points to allow the stud rail assembly to be reconfigured between a collapsed configuration and an expanded configuration.