A phase in construction scheduling is a chunk of project work grouped by trade, location, or sequence. Common phases on commercial TI work include demolition, framing and partitions, MEP rough-in, drywall and ceilings, MEP finish, finishes, FFE coordination, commissioning, and close-out. Phases have a start date, an end date, a budget, and assigned crew or sub responsibilities.
Phases differ from milestones. A phase is a span of time with work happening; a milestone is a single point marking phase completion. Phase-based scheduling lets project managers track variance per chunk of work rather than only at project total. When the estimate line items map cleanly to phases, budget vs actual reporting becomes per-phase rather than per-project, surfacing problems weeks earlier than waiting for close-out.