Scheduling & the Critical Path

A schedule turns the work into a sequence of tasks with durations — and shows what has to happen when.

Key ideas

• Activities & durations — break the job into tasks and estimate how long each takes.
• Dependencies — many tasks can't start until another finishes (you can't frame before the foundation cures).
• Critical path — the longest chain of dependent tasks; it determines the project's finish date. A delay on the critical path delays the whole job.
• Float (slack) — tasks not on the critical path have some wiggle room.

Managing the schedule

• Use look-ahead (short-interval) plans — a rolling 2–3 week view of what's coming.
• Update the schedule regularly with actual progress.
• Protect the critical path above all — that's where delays hurt most.

Going Deeper (Intermediate)

A schedule is built from tasks, durations, and dependencies (predecessors). The critical path is the longest chain of dependent tasks — it has zero float and sets the completion date. Anything on it that slips, slips the whole job. Tasks off the critical path have float (slack) you can use.

Advanced / Pro-Level

Running a schedule like a PM:

• Baseline vs. updates — set a baseline, then update progress so you can see slippage and prove delay.
• Long-lead procurement belongs in the schedule (tie it to submittals).
• Resource leveling and 3-week lookaheads keep trades and materials staged.
• Delay analysis methods (impacted as-planned, time-impact analysis) and recovery/acceleration (add crews, overtime, re-sequence) — acceleration costs money, so document who caused the delay.
• An updated CPM schedule is both a management tool and a claims tool; "the schedule" is how delay disputes are won.

Practice Challenge

Task A (5 days) → B (10) → D (4) runs in parallel with A → C (6) → D. What's the critical path, total duration, and C's float? (Answer: A-B-D = 5+10+4 = 19 days (critical); A-C-D = 5+6+4 = 15, so the finish is 19 days and task C has 4 days of float.)

In Practice

A delay on a non-critical task barely matters; a delay on the critical path pushes the whole finish date. Knowing which is which tells you where to focus.

Common Mistakes to Avoid

• Not identifying the critical path
• No look-ahead planning
• Failing to update the schedule with actuals

Takeaway: Build a sequenced schedule, find the critical path (the chain that sets the finish date), and protect it with look-ahead planning.

Educational content — not legal or contractual advice. Follow your contract's specific procedures and deadlines.