Non-sequentially installed dry joint wall panel system

A wall panel system for attachment to a building surface, said wall panel system comprising:

• a plurality of generally vertical supports;
• a plurality of generally horizontal mounting rails interconnected with said vertical supports to define a panel mounting gridwork, said horizontal mounting rails having an upper mounting feature and a lower mounting feature on a side opposite from the building surface;
• and
• a plurality of panels, each said panel having a rear surface, an upper extrusion mounted to a top of said rear surface, and a lower extrusion mounted to a bottom of said rear surface, said upper extrusion mating with a corresponding lower mounting feature on said gridwork, and said lower extrusion mating with a corresponding upper mounting feature on said gridwork, said plurality of panels having a gap about a periphery thereof relative to any adjacent panels, whereby said panels can be non-sequentially mounted to said gridwork, each said panel including an outer surface opposed to said rear surface and a top return flange and a bottom return flange that both extend at an approximate 90° angle relative to said outer surface, said top return flange extending farther than said bottom return flange.