Casting the floor first is recommended. Note that rebound and trimmings from vertical wall placement are not fully consolidated concrete and must not be used as part of a structural concrete section. Thus, casting first allows:
- No collection of rebound and trimmings from wall construction to get trapped below floor reinforcing steel.
- Provides a stable surface to collect and remove rebound and trimmings.
- Is generally faster placement and allows full consolidation of concrete throughout the floor thickness by immersion vibrators.
- If using wet-mix shotcrete the shotcrete pump can serve as a line pump for pumping concrete into the floor thus requiring no extra equipment.
- Allows proper joint preparation at the floor/wall joint to provide a watertight joint.