finish to start relationship

Today, we will discuss the finish-to-start relationship. This is the most commonly used relation in the network diagram.

Before we move into detail on the finish-to-start (FS) relationship, let’s understand the terms we’ll use.

A predecessor activity comes before a dependent activity in a schedule.

A successor activity is a dependent activity that comes after another.

A lead is when the work of a successor activity is started before the predecessor finishes and is indicated by the “-” sign.

A lag is a delay of a successor activity, denoted by the “+” sign. 

Finish-to-Start Relationship

finish to start relationship

A project network diagram can have four types of dependency:

  1. Finish-to-start
  2. Finish-to-finish
  3. Start-to-finish
  4. Start-to-start

In this blog post, I will provide you with details of the finish-to-start (FS) relationship.

According to the PMBOK Guide, “Finish to Start is a Logical Relationship in which a Successor Activity cannot start until a Predecessor Activity has finished.”

This is the most commonly used relationship in a network diagram; the start of the successor activity depends on the predecessor activity’s finish.

Representation of Finish-to-Start Activity

Here is how a finish-to-start relationship is shown in a network diagram.

Bar chart or Gantt chart of the same is below:

Example of Finish-to-Start Relationship

Let’s say you are constructing a room.

To install the ceiling, you have to construct the walls. In this example, the first activity is constructing walls, and the second activity is the ceiling.

Let’s see a scenario with lag.

After plastering the wall, you will wait for two days to let it cure, then you can start painting. Here the relation is finish-to-start with two days of lag.

Our last example has lead.

Suppose you are constructing a two-floor building. You have two activities in sequence: electrical work and painting. The duration of electrical work is ten days, and the painting will take six days.

However, as you complete the electrical work on the ground floor in five days, you begin painting while the electrical work on the second floor continues.

Here you have a finish-to-start relationship with five days of lead.

Uses of Finish-to-Start Relationship

This relationship is used in all types of project network diagrams, including activity-on-node diagrams and activity-on-arrow diagrams.

Roles of Finish-to-Start relation in Schedule Compression

This relationship is useful when the project is delayed, and the project manager has to compress the schedule.

Finish-to-start is also useful when you want to complete the project earlier and are looking for activities that can be run in parallel. 

Conclusion

Finish-to-start is the most commonly used relationship in project management and can be used in all types of network diagrams. 

Here is where this post on the finish-to-start relationship ends. Please share your experience using it in the comments section.