Critical-path float is the number of days a job can slip before the finish date moves. It is also the number most schedules hide.
Every activity on a job has a relationship to something else. Rough-in before inspection. Inspection before cover. Cover before the next trade. The critical path is the chain of those activities with no spare time between them. Float is the spare time on everything else. An activity with five days of float can slip five days and the building still finishes on the same date. An activity with zero float cannot slip at all. If it slips, the finish date slips with it.
That is the whole idea. The trouble is how it gets used.
A bar on a Gantt chart can look healthy while float is already gone. Percent complete can be on plan while the one activity that controls the date is late. Crews can be busy all day on work that has float, while the work with no float sits blocked on a missing answer, a delivery, or another trade. The job feels productive. The finish date is already moving, and nobody has named the activity that moved it.
Float disappears in small pieces. A submittal sits an extra week. An inspection gets pushed two days. A long-lead item arrives, but the crew that was supposed to set it was pointed at a room that was easier to reach. None of those events looks like a crisis. Added together, they consume the slack that was supposed to protect the date. By the time float hits zero, the recovery is overtime, resequencing, or a change in the completion promise.
Negative float is the same fact, stated late. The schedule is already saying the finish date cannot be met on the current logic. More meetings do not fix that. A decision does: accelerate the activity, remove the constraint, or reset the date and own it.
The useful check is short. Which activities have zero float, or are close to it. What is blocking each one: material, access, an RFI, an inspection, manpower. Whether that blocker is owned by someone who can clear it this week. If the look-ahead is full of work that has float, and the zero-float work is waiting on a text, the schedule is a wish.
Click Construction treats float as a constraint list, not a report. The activities that control the date stay attached to the thing blocking them, and that update reaches the field and the office while there is still time to act. The superintendent is not asked to re-decide, every morning, which task actually matters. The work with no slack is already named. The work that can wait is not allowed to crowd it out.
Float is not padding. It is the only honest measure of whether tomorrow’s plan can survive a normal day on a commercial job. When it is visible early, the decision is small. When it is discovered at zero, the decision is expensive.