Setting dependencies between tasks is the most powerful feature of Gantt Excel. The in-built auto-scheduling automation of the template is able to update the dates of tasks based on changes that are made to its dependent tasks.
Definition of Task Dependency
Task Dependency is a relationship in which a task or milestone relies on other tasks to be performed (completely or partially) before it can be performed. This is also referred to as a logical relationship. It is important to understand the types of dependencies that can be used in Gantt Excel Ultimate.
4 types of task dependencies are supported in Gantt Excel Ultimate
- Finish-to-Start (FS)
- Start-to-Start (SS)
- Finish-to-Finish (FF)
- Start-to-Finish (SF)
This is the most common type of dependency between tasks and a type that is used most often. This dependency means that if there are 2 tasks TASK A and B, then TASK A (FS) B means that, the dependent task (B) cannot begin until the task that it depends (A) on is complete.. In other words if TASK A is delayed by a day, then TASK B will also be delayed and will begin a day later.
Example: If you are building the foundation for your house and you have two tasks, “Excavate” and “Pour concrete,” the “Pour concrete” task cannot begin until the “Excavate” task is complete
This dependency means that if there are 2 tasks TASK A and B, Task B can’t start until Task A starts. They don’t have to start at the same time: Task B can begin any time after Task A begins.
Example: To save time, you want to level concrete at one end of the foundation while it is still being poured at the other end. But Level concrete (Task B) can’t start until Pour concrete (Task B) has also started.
This dependency means that if there are 2 tasks TASK A and B, Task B can’t finish until Task A is completed. They don’t have to end at the same time: Task B can end any time after Task A ends.
Example: Your team is adding the wiring to the building and inspecting it at the same time. Until Add wiring (Task A) gets done, you won’t be able to finish Inspect electrical (Task B).
Task B can’t finish until Task A begins. Task B can finish any time after Task A begins. This type of link is rarely used.
Example: The wooden window frames for your house are built off-site. You can’t finish Assemble windows (Task B) until Window frame delivery (Task A) begins.
Lag time, a time interval, can be set between dependent tasks to allow for required delays. For example, in a construction project, you need to let the foundations set before building the walls. In this case, lag time should be set for concrete to set. A successor task can only start once the defined lag time (specified in days) has elapsed.
Creating a Task Dependency
The easiest way to create a task dependency is to double click a task and then set dependencies from the right pane.
- Click on the dropdown under Predecessor – Task name and select the predecessor task, set the dependency type and lag.
- Click the Add button to add the dependency and click Ok to finish. A task dependency is set instantly.
Modifying Task Dependency
To modify a task dependency just double click a task and then you can add/ edit or delete existing dependencies.
- To edit a dependency, select the task dependency and click the edit button. Click the Save button when you finish.
- To delete a dependency, select the task dependency and click the delete button.