Abstract: A flooring system comprising a plurality of spaced load-bearing joists and flooring members which are carried thereby, extending at right-angles thereto. Each flooring member has a web and a pair of downwardly-depending flanges, and each joist is of generally triangular cross-section, with spaced pairs of slots for accommodating the flanges of the flooring members. Each slot of a pair thereof has a lesser length than the depth of the associated flange, but the flange also is provided with slots for accommodating parts of the associated joist, whereby the web of each flooring member may bear on the top faces of the joists it crosses. The flooring members and the joists may be made of a plastics material, such that the flooring members may be snap-fitted to the joists. The flooring members may be perforated and the pairs of slots in the joists spaced by such distances that there are gaps between parallel members, resulting in a ventilated floor which is particularly suitable for use in animal enclosures.