Multiple polymeric panels molded as a rigid integral body having a planar top surface and a bottom grid structure are interlocked together mechanically along side edges. Each side edge has alternating upwardly and downwardly facing steps with concave dimples on one and mating convex projections on the other for securely interlocking adjacent panels to each other. The steps of adjacent panels interlock with each other to form a complete floor system. The multiple polymeric panels can be molded to simulate flooring materials such as brick or overlaid with sections of linoleum, carpet, synthetic grass, tile or wood flooring. Alternately, the assembled panels can be covered with a sheet of decorative material.

An HVAC air handling enclosure is comprised of individual panel assemblies each of which are fabricated from two panels or skins that are held together by double-sided adhesive tape. Adjacent panel assemblies are connected by a metal tongue-and-groove joint that relies on that same tape as a thermal break at the joint. After assembly, the thermal break and the tongue and groove elements of the joint are completely hidden from view. Moreover, the joint includes an internal cavity that can take up surplus sealant that may ooze out from within the tongue-and-groove joint during assembly, whereby the surplus sealant also remains hidden.

Floor panels (1, 1') are provided with a mechanical locking system including a flexible tongue (30) in a sliding groove (40) which during a vertical folding motion is displaced. Moreover, a tongue blank (50), a production method and an installation method are shown.

The invention relates to a locking system for mechanical joining of floorboards (1, 1'), a floorboard having such a locking system and a flooring made of such floorboards. The locking system has mechanical cooperating means (36, 38; 6, 8, 14) for vertical and horizontal joining of adjoining floorboards. The means for horizontal joining about a vertical plane (F) comprise a locking groove (14) and a locking strip (16) which is located at opposite joint edge portions (4a, 4b) of the floorboard (4). The locking strip (6) projects from the joint plane (F) and has an upwards projecting locking element (8) at its free end. The locking groove (14) is formed in the opposite joint edge portion (4a) of the floorboard at a distance from the joint plane (F). The locking groove (14) and the locking element (8) have operative locking surfaces (10, 11). The locking surfaces are essentially plane and spaced from the upper side of the projecting strip and inside the locking groove and make a locking angle (A) of at least 50.degree. to the upper side of the board. Moreover the locking groove has a guiding part (12) for cooperation with a corresponding guiding part (6) on the locking element (8).

A locking system for mechanical joining of floorboards has a locking groove which is formed in the underside of and extends in parallel with the first joint edge at a distance from the joint plane, and a portion projecting from the lower part of the second joint edge and below the first joint edge and integrated with a body of the board. The projecting portion supporting at a distance from the joint plane a locking element cooperating with the locking groove and thus positioned entirely outside the joint plane seen from the side of the second joint edge, the projecting portion having a different composition of materials compared with the body of the board. The projecting portion presents at least two horizontally juxtaposed parts, which differ from each other at least in respect of the parameters material composition and material properties.