Wall panel system

Claim 1

A wall panel comprised of extruded plastic units, each having a plurality of forwardly-facing vertically-spaced, horizontally-extending similar flat lands supported on the ends of arms of C-shape channels having forwardly open mouths, the longitudinal edges of the lands constituting lips which overhang the channel mouths and which are adapted to be engaged by mounting clips, prongs and the like of hangers, and joint means having cooperating parts which extend along upper and lower horizontal edges of the units for securing a lower edge of an upper unit to an upper edge of the next lower unit, wherein that part of the joint means which is on the lowermost edge of an upper unit is supported on one arm of a channel and, together with said one arm, respectively define first and second adjacent sides of an open-ended generally rectangular box, a third side of said box being constituted by a wall parallel to and spaced from the lowermost land, the fourth side of the box being spaced from and parallel to said second adjacent side and terminating short of the third side of the box and providing therebetween a gap, the part of the joint means extending along the upper edge of the next lower unit comprising an inverted "T"-shape flange as seen in cross section, said flange slideably engaging endwise in the box of the other joint part with one end of the head of the inverted "T"-shape flange engaging in said gap, the stem of the inverted "T"-shape flange engaging behind the fourth side of the box and the head of the inverted "T"-shape flange engaging against the third side of the box.