A tiedown system foundation adapter system provides greater flexibility in spotting equipment on a support surface. An adapter module includes a plate assembly that drops into a slotted track system and is slid along the track system until it fits into an attachment point that restrains the plate assembly from vertical pullout and motion transverse to the track. The plate assembly is then locked into position to restrain it from further translation along the track. An equipment fitting is translatably mounted with respect to the upper surface and attaches to a complementary attachment fitting on the bottom of a piece of equipment. By locating a number of modules in desired locations along the tracks and locating the equipment fitting in each module, a piece of equipment can be oriented in virtually any position and location in the space to be furnished. A deck system for a flush floor is also provided.