Non-walkable clean room ceiling, mounting system, and method

A clean room ceiling system for use inside a building structure, the system comprising:

• a) an inverted T-shaped beam, the inverted T-shaped beam defining a beam upright, the beam upright being configured to be supported by the building structure, the inverted T-shaped beam defining opposing beam legs, the opposing beam legs extending laterally from the beam upright and defining a beam bottom, each beam leg terminating in a beam joint portion, each beam joint portion extending generally in an upward direction from each beam leg, each beam joint portion defining a beam joint upper end and a beam joint lower end;
• b) a composite ceiling panel, the composite ceiling panel having a top skin, a bottom skin and a core disposed between the top and bottom skins, the composite ceiling panel defining a periphery, the periphery of the composite ceiling panel defining a panel joint portion, the panel joint portion defining a panel joint lower end and a panel joint upper end, the panel joint portion being configured for an engagement with the beam joint portion, wherein the panel joint portion and the beam joint portion define a relief when the panel joint portion and the beam joint portion are in engagement so that the beam joint lower end engages the panel joint lower end and the beam joint upper end does not engage the panel joint upper end.