Abstract: Adjustable slotted rim track for securing peripheral edges of a joist-floor panel assembly has a generally U-shaped planar web with interior depending tabs and opposite depending flanges normal to and separated by the web. The depending flanges may have a series of parallel adjustment slots for receiving fasteners through the flanges to connect and secure the rim track to a framing member such as a floor joist or floor panel assembly. Another design provides adjustment slots on the tabs instead of flanges. The slotted tabbed rim track design allows the joist-floor panel assembly to move relative to the rim track. Tabbed slots or angle clips affixed to the interior planar area of the rim track web are utilized for secure fastening of the adjustable rim track to the joist framing member during final installation of the assembly.