A floor assembly for a trailer includes stringers that extend in a transverse direction of the assembly and are spaced from one another in a longitudinal direction of the assembly. The stringers are made of a thermally insulative first material. A bottom flange is coupled to a lower portion of a respective stringer. A top flange made of a second material is coupled to an upper portion of a respective stringer. Floor panels are also provided. Each floor panel extends in the longitudinal direction, is supported by the top flange, is coupled to another floor panel along respective edges thereof, and has at least one rib that extends in the longitudinal direction and depends substantially perpendicularly from a bottom surface thereof. Each floor panel is made of the second material and each at least one rib is welded to a top surface of the top flange.