Today, we will discuss the finish-to-start relationship. This is the most commonly used relation in the network diagram. Show
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 RelationshipA project network diagram can have four types of dependency:
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 ActivityHere 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 RelationshipLet’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 the 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 RelationshipThis 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 CompressionThis 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. ConclusionFinish-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. What is Finish to Start dependency? 1 Answers The Finish to Start dependency is the default link type applied. It forces a task to start only when/after its predecessor has finished; predecessor finishes and the other starts. In a project network, a dependency is a link among a project's terminal elements.[citation needed] The A Guide to the Project Management Body of Knowledge (PMBOK Guide) does not define the term dependency, but refers for this term to a logical relationship, which in turn is defined as dependency between two activities, or between an activity and a milestone.[1] Standard types of dependencies[edit]There are four standard types of dependencies:
Finish-to-start is considered a "natural dependency". The Practice Standard for Scheduling recommends, that "Typically, each predecessor activity would finish prior to the start of its successor activity (or activities)(known as finish-to-start (FS) relationship). Sometimes it is necessarily to overlap activities; an option may be selected to use start-to-start (SS), finish-to-finish (FF) or start-to-finish (SF) relationships....Whenever possible, the FS logical relationship should be used. If other types of relationships are used, they shall be used sparingly and with full understanding of how the relationships have been implemented in the scheduling software being used. Ideally, the sequence of all activities will be defined in such a way that the start of every activity has a logical relationship from a predecessor and the finish of every activity has a logical relationship to a successor".[2] SF is rarely used, and should generally be avoided. Microsoft recommends to use SF dependency for just-in-time scheduling.[3] It can be easily shown however, that this would only work if resource levelling is not used, because resource levelling can delay a successor activity (an activity, which shall be finished just-in-time) in such a way, that it will finish later than the start of its logical predecessor activity, thus not fulfilling the just-in-time requirement. There are three kinds of dependencies with respect to the reason for the existence of dependency:
Early critical path-derived schedules often reflected only on causal (logical) or discretionary (preferential) dependencies because the assumption was that resources would be available or could be made available. Since at least the mid-1980s, competent project managers and schedulers have recognized that schedules must be based on resource availability. The critical chain method necessitates taking into account resource constraint-derived dependencies as well. Leads and lags[edit]Dependencies can be modified by leads, and lags. Both leads and lags can be applied to all 4 types of dependencies. PMBOK defines lag as "the amount of time whereby a successor activity will be delayed with respect to a predecessor activity". For example: When building two walls from a novel design, one might start the second wall 2 days after the first so that the second team can learn from the first. This is an example of a lag in a Start-Start relationship. In accordance to PMBOK a lead is "the amount of time whereby a successor activity can be advanced with respect to a predecessor activity For example, on a project to construct a new office building, the landscaping could be scheduled to start prior to the scheduled punch list completion. This would be shown as a finish-to-start with two-week lead".[1] Example[edit]If you are building a building, you can't paint the walls before installing the water pipes into the walls. Advanced cases of activities dependencies[edit]Maximal-type relationships[edit]Activity A and Activity B are said to have a Maximal-Type Relationship, if Activity B can start after Activity A, but with the delay of no more than X.[4] Real life examples, which are simulated by Maximal-Type Relation:
Maximal-type relationships are rarely implemented in the project management software, most probably because with this feature it is too easy to create contradictory dependencies. See also[edit]
References[edit]
What is Finish to Finish dependency?What is Finish to Finish dependency? The Finish to Finish dependency forces a task to finish only when/after its predecessor is completed; both tasks finish at the same time. If a nonzero lag is present, it is added to the Finish date.
What is a start to start dependency?A Start-to-Start (or SS) dependency means that a successor activity cannot begin before its predecessor has started. They do not however have to start at the same time. These dependencies are common within projects which require their tasks to run parallel to one another.
Why is it finish to start dependency?A Finish-to-Start (FS) dependency is perhaps the most common dependency type that you will come across in projects. This is due to the fact that this 'type' means a successor (second task) cannot begin until its predecessor (first task) is complete, which is the most common scenario in projects.
What is an example of a finish to finish dependency?Finish-to-Finish (FF)
For example, “Fracking cannot finish until pressure testing is complete” “Electrical work cannot finish until drywalling is complete.” “Design work cannot finish until environmental studies are complete”
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