# Finish to Finish Relationship

## PDM Relationships – Finish to Finish

This article extends my previous article on Project Network Diagram. Project Network Diagrams are used to pictorially represent Project Schedule and Project Dependencies. You can also read my other articles on Project Dependencies – What are Project Dependencies and 4 Types of Project Dependencies.

There are many ways to draw a Project Network Diagram. One of them is Precedence Diagramming Method (PDM). PDM defines 4 Logical Relationships to represent Project Dependencies. This post to describes Finish to Finish (FF) Relationship.  Finish to Finish is one of the 4 Logical Relationships. The other 3 Logical Relationships are Finish to Start, Start to Start and Start to Finish.

### Definition of Finish to Finish Relationship

It is a Logical Relationship in which a Successor Activity cannot finish until a Predecessor Activity has finished. In other words, the Finish of a Successor is Dependent on Finish of the Predecessor.

Most Project Management Authors treat above definition of FF Relationship as standard. However, some Scheduling Software treat FF Relationship slightly differently. They treat FF Relationship as “Must Finish Together” Relationship. So, if one one of the activities Starts other is Automatically Started.

The most common and most natural relationship is Finish to Start (FS). Finish to Finish Relationship is not widely used. The Project Managers have some flexibility while defining the relationship between 2 activities. Usually it is possible for them to transform a FF Relationship to a FS Relationship.

You can also look at Max Wideman’s Glossary for complete set of definitions on PDM Logical Relationships.

### Project Network Diagram Representation

Let us consider two activities A and B.

• Duration of A – 3 days
• Duration of B – 1 day
• B has a Finish to Finish Relationship with A – B cannot Finish until A Finishes

The Project Team will need a total of 3 days to complete these activities.

### Mathematical Representation

B can Finish (F) only after A Finishes (F)

B(F) = A(F)

### Examples

Let us consider 2 activities A and B. Let us also consider A to be the Predecessor and B to be the Successor.

• A – Write Code for S/W Module X, B – Unit Test S/W Module X
• A – Lay Electrical Wires, B – Inspect Electrical Wires

You can also look at some of my other articles on Precedence Diagramming Method