Phase 1 — STEEL FRAME: erect columns, beams, bracing per erection plan. Plumb and align. Final bolt-up (snug-tight, pretensioned, or slip-critical per connection schedule). HOLD POINT: structural steel inspection (connections, plumb, alignment). Phase 2 — METAL DECK: install composite floor deck (typically 2in or 3in corrugated steel, 20 gauge). Weld puddle welds or mechanically fasten to beams. Shear studs welded through deck to beams (3/4in dia typical). Deck edge pour stops and slab closure pieces. Phase 3 — CONCRETE FILL: place lightweight or normal weight concrete over deck (typically 3.25in above deck ribs for 2hr rating). Welded wire reinforcement or fiber reinforcement. HOLD POINT: deck/stud inspection before pour. Phase 4 — CORE/MEP: core walls, stairs, elevator shafts. MEP rough follows steel frame up the building. Trades sequence: sprinkler → mechanical duct → plumbing → electrical → data.