Abstract: A frame assembly for an environmental enclosure including a plurality of channel-shaped members each including an end wall, opposed spaced side walls and an opening opposite the end wall adapted to receive and retain an end cap for retaining a film over the frame assembly having an integral internal channel which receives a connector element for interconnecting the frame members into a rectangular frame assembly and the frame assemblies are then interconnected to form an environmental enclosure. In one embodiment, the channel-shaped frame members include a generally L-shaped connector portion integral with one of the side walls for interconnecting the frame assemblies in side to side and end to end relation. In the other embodiment, the rectangular frame assembly has a height equal to the height of the environmental enclosure and transverse bracing elements having a U-shaped connector plate including transverse slots received in the internal channel.