Patent ID: 8739475

Claim:
A foldable building unit, comprising (a) a first frame element having a first structural load carrying member selected from the group comprising a hollow structural metal section, a metal C-channel, a metal I-beam, a metal T-beam, a metal angle beam, and a metal wide-flange beam; (b) a second frame element having a second structural load carrying member selected from the group comprising a hollow structural metal section, a metal C-channel, a metal I-beam, a metal T-beam, and a metal wide-flange beam; provided that the first structural load carrying member and the second structural load carrying member are not both hollow structural metal sections; and (i) the first structural load carrying member and the second structural load carrying member are lengthwise connected to form a fixed connection between the first frame element and the second frame element, or (ii) the first structural load carrying member and the second structural load carrying member are lengthwise foldably connected to allow folding of the first frame element and the second frame element relative to each other; wherein the first structural load carrying member is positioned relative to the second structural load carrying member to allow direct fastening between the first structural load carrying member and the second structural load carrying member from outside the foldable building unit.