Scheduling · August 2026 · 5 min read
Reading a construction Gantt chart without lying to yourself
A bar on a chart is only as true as the start and due dates behind it. Here is what to check before you treat the picture as the plan.
A Gantt chart looks decisive. A bar crossing three months feels like a commitment. It is only a drawing of two dates: when the task starts and when it is due. If those dates were guessed, the bar is a guess with better graphics.
Before a review, check three things. Does every bar you care about have both a start and a due date, or did one of them default because only one date was entered? Is the today line inside the window, and are bars that should already be finished still open? Is the chart filtered to the project you are discussing, or are you looking at every job at once?
A predecessor on a task records that one task depends on another. That is a fact about the sequence. It is not, by itself, a critical-path calculation, and the Best CPMS chart does not draw arrows between bars. If you need the sequence, open the task. If you need the dates, read the bar.
Milestones are the dates other people will remember. Use them for the points that end a stage, and use tasks for the work between those points. A chart with only milestones is too coarse. A chart with only tasks hides the dates the client will ask about.
Update the dates when the site changes them. A chart that is rebuilt from current task dates is allowed to look worse than last week’s export. That is the version worth taking into the meeting.