Abstract: An industrial cleanroom structure including a plenum enclosure assembly positioned above a cleanroom enclosure assembly. The plenum assembly includes plenum support structure rigidly attached and including top and bottom covers and sidewall covers sealed to prevent entry of microcontamination into the plenum enclosure. The plenum top cover includes openings for receiving air propelled by overhead fans into the plenum area. The plenum bottom cover comprises a filter system through which air is expelled into the cleanroom enclosure. The cleanroom enclosure includes a plurality of fabricated wall studs removably attached to the plenum support structure in vertical orientation to form wall support structure having exact vertical and horizontal alignment. At least one horizontal span cord is coupled to the plenum support structure and indirectly to the wall support structure to rigidly tie all coupled studs together in load sharing relationship.