Scheduling guide
By Firat Acar, Founder and CEO, Plan104 · October 25, 2026
The critical path method (CPM) is the standard way to plan and control construction projects. This guide explains how a CPM schedule is built, what the critical path and float really mean, and what separates a schedule the field trusts from one that only lives in the office.
A CPM schedule breaks the project into activities. Each activity has a duration and is connected to other activities through logic, also called relationships. The most common relationship is finish to start: one activity must finish before the next can start. Start to start and finish to finish relationships, sometimes with lags, describe work that overlaps.
Once activities, durations and logic are in place, scheduling software such as Oracle Primavera P6 runs a forward pass to find the earliest each activity can start and finish, and a backward pass to find the latest it can start and finish without delaying the project.
The critical path is the longest continuous chain of activities through the schedule. Any delay to an activity on the critical path delays the completion date by the same amount, unless the work is resequenced or accelerated. On a large project the critical path often moves from update to update, which is why every schedule update should explain what is driving the finish date.
Total float is the amount of time an activity can slip before it delays the project. Free float is the time it can slip before it delays the next activity. Activities with zero or negative total float are critical. Negative float means the schedule, as it stands, cannot meet a required date.
The biggest weakness of most CPM schedules is that crews never see them. A thousand-line schedule is hard to read on site. Plan104 solves that with a construction operations platform that turns the schedule into a live simulation and personal daily work reports for every person on site.
If you need a CPM schedule built, updated or reviewed, see our construction scheduling services and Primavera P6 scheduling.
CPM stands for critical path method, a scheduling technique that uses activities, durations and logic to calculate the longest path of work and the project completion date.
Total float is how long an activity can slip without delaying the project. Free float is how long it can slip without delaying the next activity.
Oracle Primavera P6 is the most common CPM scheduling software on large construction projects. Microsoft Project is also used on smaller jobs.
Tell us about your project and where the schedule stands today. We will show you how we would build, update or recover it, and how the platform puts it in front of every crew on site.