Gantt LWC - Creating Predecessors in the Gantt Chart

Last Modified On: April 2, 2025

Predecessors specify the relationships between project tasks and indicate when a task should begin or end in relation to other tasks. 
 

Predecessor relationships can be created either by:

• Populating the Predecessor Column (see Gantt LWC - Defining Task Relationships), OR
• Defining Predecessors within the Gantt Chart 

Understand Predecessor Types

Inspire Planner supports the four (4) common types of dependencies:

• Finish to Start (FS),
• Start to Start (SS),
• Finish to Finish (FF), and
• Start to Finish (SF)
   

Finish to Start (FS)

Finish-to-Start predecessors are the most commonly used type of dependency. When a Finish-to-Start predecessor is used to connect two tasks, this means that Task B cannot start before Task A is finished. The image below shows an example of a Finish-to-Start type of predecessor.

Start to Start (SS)

When a Start-to-Start predecessor is used to connect two tasks, this means that both tasks start at the same time. However, these tasks can finish at different points in time. The image below shows an example of a Start-to-Start type of predecessor.

Finish to Finish (FF)

When a Finish-to-Finish predecessor is used to connect two tasks, this means that both tasks finish at the same time. However, these tasks can begin at different points in time. The image below shows an example of a Finish-to-Finish type of predecessor.

Start to Finish (SF)

Start-to-Finish relationships are the least commonly used in project planning. When a Start-to-Finish predecessor is used to connect two tasks, this means that Task A cannot finish until Task B starts. The image below shows an example of a Start-to-Finish type of predecessor.  The image below shows an example of a Start-to-Finish type of predecessor.

Define Predecessors in the Gantt Chart

Defining predecessor relationships between Project Tasks in the Gantt Chart is done by either:

• Drawing a line between Project Tasks, OR
• Populating the Predecessor Information for Tasks on the Gantt Chart

Drawing a Line between Project Tasks

You can define predecessor relationships by drawing a line between Project Tasks to connect them. 

Finish to Start (FS)

To create a Finish to Start type of predecessor between two tasks, simply hover over Task A until you see two circles appear on each end. Then draw a line from the end of Task A to the start of Task B (see green line in the image below).

As you connect the tasks, a tooltip displays that lets you know if the dependency is valid (allowed) or invalid (not allowed).

Start to Start (SS)

To create a Start to Start type of predecessor between two tasks, simply hover over Task A until you see two circles appear on each end. Then draw a line from the start of Task A to the start of Task B (see green line in the image below).

As you connect the tasks, a tooltip displays that lets you know if the dependency is valid (allowed) or invalid (not allowed).

Finish to Finish (FF)

To create a Finish to Finish type of predecessor between two tasks, simply hover over Task A until you see two circles appear on each end. Then draw a line from the end of Task A to the end of Task B (see green line in the image below).

As you connect the tasks, a tooltip displays that lets you know if the dependency is valid (allowed) or invalid (not allowed).

Start to Finish (SF)

To create a Start to Finish type of predecessor between two tasks, simply hover over Task B until you see two circles appear on each end. Then draw a line from the start of Task B to the end of Task A (see green line in the image below).

As you connect the tasks, a tooltip displays that lets you know if the dependency is valid (allowed) or invalid (not allowed).

Invalid Dependencies

Inspire Planner prevents you from creating invalid dependencies. When you attempt to create an invalid dependency, an error displays to let you know that the dependency you are trying to create is invalid (not allowed). Examples of invalid dependencies include:

• A dependency between a parent task and its subtasks
• A circular dependency (for example, Task C is dependent on Task B that is dependent on Task A that is dependent on Task C).

Adding Predecessors in Task Dialogue

Another way to create predecessor relationships is via the Task dialogue.
 

1. To open the task dialogue, double-click on the task bar in the Gantt chart.
   
   
    
2. The task dialogue will open onscreen. Click on the Predecessors tab.
   
   
    
3. Click on the Add icon.
   
   
    
4. In the Name column, you can click on the drop-down arrow to see all tasks in the project. You can also start typing in the name of a task, and it will narrow down the tasks displayed in the drop-down. Click on a task to select it.
   
   
    
5. Double-click on the Type field to adjust the dependency type.
   
   
    
6. If the task has multiple predecessors, click on the Add icon again and then fill in the details of the other predecessor task.
   
   
    
7. To remove a predecessor, select the task first and then click on the Recycle Bin.
   
   
    
8. Click on Save when you are finished.
   
   
    
9. The task dialogue will close, and the predecessor column will display the row number(s) of the predecessor task(s).
   
   

Add Lag or Lead Time

You can add Lag or Lead time between dependent tasks in the Gantt chart. Simply hover over the dependency line connecting the task bars. The line will turn into a darker line. Then, double-click on it.

You can then adjust the lag or lead time in days. Use the up and down arrows to adjust the value. Click on Save when finished.

The value in the Predecessor column for the task will also reflect the lag/lead time you specified.