Gantt Chart & CPM Scheduling
The Gantt chart is where your project schedule comes to life. It draws every task as a horizontal bar on a timeline, connects them with dependency arrows, and highlights the critical path so you know exactly which tasks control your project end date. Combined with the built-in Critical Path Method (CPM) engine, it gives you a scheduling tool purpose-built for residential construction.
What is the Gantt Chart?
A Gantt chart is a visual timeline. Each task appears as a horizontal bar whose length represents its duration. Tasks are stacked vertically in the order they appear on your task list, and dependency arrows show which tasks must finish before others can start.
In Baulit, the Gantt chart does more than display bars. It runs the CPM engine on your task network and color-codes the results: critical tasks in red, tasks with float in blue, and unscheduled tasks in gray. At a glance, you can see your project duration, identify bottlenecks, and find where you have scheduling flexibility.
Accessing the Gantt Chart
Open the Gantt chart from any project:
- Go to your project and click the Schedule tab at the top of the project view.
- Alternatively, click Gantt in the project header bar for a direct shortcut.
The Gantt chart fills the right side of the screen. Your task list remains on the left so you can reference task names while reading the timeline.
The Network Health Banner
At the top of the Gantt chart, a colored banner reports the health of your task network. This banner tells you whether your schedule has enough information for CPM to produce meaningful results.
Green: Fully Connected
Every task has a duration and at least one dependency connection (either as a predecessor or successor). Your network is complete and the critical path calculation is reliable. This is your target state.
Amber: Partially Connected
Some tasks are missing durations or have no dependency connections. CPM still runs on the connected portion of the network, but orphan tasks are excluded from the critical path calculation. The banner shows a health percentage: the number of tasks with both a duration and at least one connection divided by the total task count.
Red: Circular Dependency Detected
The engine found a cycle in your dependency chain. For example, Task A depends on Task B, Task B depends on Task C, and Task C depends on Task A. CPM cannot run until you break the cycle. The banner identifies which tasks are involved so you can fix the issue in the Dependency Wizard.
Understanding CPM
The Critical Path Method is a scheduling algorithm that calculates the shortest possible duration for your project based on task durations and their dependency relationships. It has been the standard scheduling technique in construction since the 1950s, and Baulit runs it automatically every time your task data changes.
How CPM Works
CPM performs two passes through your task network:
The Critical Path
Tasks where the earliest start equals the latest start have zero float. These tasks form the critical path. If any critical task slips by even one day, the entire project end date moves by one day. The critical path is the longest chain of dependent tasks through your project, and it defines your minimum project duration.
Float (Slack)
Float is the number of working days a task can be delayed without pushing the project end date. A task with 5 days of float can start up to 5 days late (or take 5 extra days to complete) before it becomes a problem. Float gives you scheduling flexibility for non-critical work.
Dependencies: Finish-to-Start Only
All dependencies in Baulit are Finish-to-Start (FS): the predecessor task must finish before the successor task can start. This is the most common and most intuitive relationship in construction scheduling. Your framing crew finishes before the roofers start. The rough-in inspection passes before drywall begins.
Duration in Working Days
Task durations are measured in working days (Monday through Friday). A 5-day task that starts on Monday finishes on Friday. A 5-day task that starts on Thursday finishes the following Wednesday. The Gantt chart handles weekends automatically when a project start date is set.
How CPM Looks on the Gantt Chart
The diagram below shows a simple 5-task network for a residential project. The critical path runs through Foundation, Framing, Roofing, and Inspection. The Plumbing Rough-In runs in parallel and has float because it takes fewer days than the Framing-to-Roofing path.
In this example, the critical path runs across the top: Foundation (5 days), Framing (8 days), Roofing (3 days), and Inspection (1 day), totaling 17 working days. The Plumbing Rough-In takes only 4 days but cannot start until the Foundation is done and must finish before the Inspection. Since the parallel critical path takes 12 days (Framing + Roofing + Inspection) but plumbing only takes 4 days, the plumbing crew has 7 days of float.
The next diagram walks through the actual forward and backward pass calculations on a simpler 4-task network. Each box shows the Early Start / Early Finish on top and Late Start / Late Finish on the bottom, so you can see exactly how float is calculated.
Reading the Gantt Chart Bars
Every bar on the Gantt chart is color-coded to tell you its scheduling status at a glance.
| Bar Color | Meaning |
|---|---|
| Red | Critical path task. Zero float. Any delay pushes the project end date. |
| Blue with gray padding | Non-critical task with float. The gray extension shows how many days the task can slip. |
| Dark thin bar with triangles | Phase summary bar. Automatically spans from the earliest child start to the latest child finish. |
| Gray | Unscheduled task. Missing a duration, missing predecessors, or disconnected from the network. |
| Green | Completed task. Work is done and approved. |
Dependency arrows connect predecessor bars to successor bars. The arrows help you trace the logic of your schedule and see why a particular task is scheduled where it is.
Task Popover
Click any task bar on the Gantt chart to open the task popover. This floating panel gives you quick access to scheduling details and editing tools without leaving the chart.
The popover shows:
- Duration and predecessors with inline editing
- Early Start (ES) and Early Finish (EF) — the earliest the task can begin and end
- Late Start (LS) and Late Finish (LF) — the latest the task can begin and end without delaying the project
- Total Float — how many working days the task can slip
- A link to open the task in the full Dependency Wizard for detailed network editing
Zoom Controls
Construction projects range from a two-week renovation to a twelve-month custom home. The Gantt chart provides multiple zoom levels to match your project scope.
Named Zoom Buttons
Three buttons above the chart set common zoom levels:
- Day — one column per working day. Best for short projects or detailed weekly planning.
- Week — one column per week. The default view. Good for most residential projects.
- Month — one column per month. Best for long projects or portfolio-level overviews.
Fine Adjustment
Use the + and - buttons for incremental zoom changes between the named levels. Your scroll position is preserved when zooming so you stay focused on the same part of the timeline.
Keyboard Shortcuts
When the Gantt chart has focus:
- Cmd + = — zoom in
- Cmd + - — zoom out
Phase Summary Bars
If you organize tasks into phases (like Pre-Construction, Foundation, Framing, etc.), the Gantt chart automatically generates a summary bar for each phase. These thin dark bars with triangular endpoints span from the earliest start date of any child task to the latest finish date of any child task within the phase.
Phase summary bars give you a high-level timeline view. You can see at a glance that the Framing phase runs from week 3 to week 6, even if it contains twelve individual tasks with complex dependencies.
Project Start Date and Calendar Dates
The Gantt chart can display two types of timelines:
- Relative day numbers (Day 1, Day 2, Day 3...) — shown when no project start date is set.
- Real calendar dates (Mon Jan 6, Tue Jan 7...) — shown when you set a project start date in Edit Project.
When calendar dates are active, the Gantt chart accounts for weekends automatically. A 5-day task starting Monday finishes Friday. A 5-day task starting Thursday finishes the following Wednesday (skipping Saturday and Sunday).
Building Your Network for CPM
The critical path is only as good as the data behind it. For CPM to produce meaningful results, every task needs two things: a duration (in working days) and at least one dependency connection.
Practical Tips for Builders
- Watch the red bars. Your critical tasks need the most attention. If a critical task is at risk of slipping, that is where to focus your resources.
- Use float strategically. Tasks with high float can absorb delays. If you need to pull a crew off one task to help a critical task, choose the task with the most float.
- Do not chain everything serially. Real construction has parallel work streams. Foundation work enables both framing and underground plumbing. Framing enables both roofing and exterior sheathing. Build your network to reflect how work actually happens on site.
- Update statuses daily. CPM calculations use task status information. Marking tasks complete as they finish keeps the schedule accurate and shows your team what is coming next.
- Re-check after changes. When a change order adds tasks or modifies durations, the Gantt chart recalculates automatically. Check whether the critical path shifted, as new work may have created a longer chain.
Common Questions
Why are some tasks gray on the Gantt chart?
Gray bars mean the task is unscheduled. It is either missing a duration, missing predecessor connections, or both. Open the task to add the missing information, or use the Dependency Wizard to connect it to the network.
Why did my critical path change after I added a task?
The critical path is the longest chain through the network. Adding a new task with dependencies may create a longer chain than the previous critical path. This is normal. Review the new critical path to make sure it reflects the actual sequence of work.
Can I manually set a task as critical?
No. The critical path is calculated automatically by the CPM engine based on durations and dependencies. You cannot override it. If you want a task to be on the critical path, adjust its dependencies or durations to reflect the real constraints of your project.
What happens when I mark a critical task as complete?
The CPM engine recalculates with the remaining tasks. The critical path may shift to a different chain of tasks. This is expected behavior as your project progresses.