Finish-to-Start (FS) Dependency
A Finish-to-Start (FS) dependency is a logical relationship in which a successor activity cannot start until a predecessor activity has finished.
Explanation
Finish-to-Start is the most common and intuitive dependency type in project scheduling. It represents the natural sequence where one activity must be completed before the next can begin. For example, the foundation of a building must be poured (predecessor finishes) before the framing can begin (successor starts).
FS dependencies account for the vast majority of relationships in most project schedule network diagrams. When no specific relationship type is stated, FS is the default assumption in project management tools and on the PMP and CAPM exams. The critical path method relies heavily on FS relationships to calculate early start, early finish, late start, and late finish dates.
Leads and lags can be applied to FS relationships to adjust timing. A lead on an FS relationship allows the successor to start before the predecessor fully finishes (overlapping work). A lag introduces a waiting period after the predecessor finishes before the successor can start. For example, concrete must cure (lag) after pouring before the next construction phase begins.
Key Points
- •Most common dependency type in project scheduling
- •Successor cannot start until predecessor finishes
- •Default relationship type when none is specified
- •Can be modified with leads (overlap) or lags (waiting period)
Exam Tip
FS is the default relationship. If an exam question describes a dependency without specifying the type, assume it is Finish-to-Start.
Frequently Asked Questions
Related Topics
Precedence Diagramming Method (PDM)
The Precedence Diagramming Method (PDM) is a technique used to construct a schedule model in which activities are represented by nodes and are graphically linked by logical relationships to show the sequence of activities.
Start-to-Start (SS) Dependency
A Start-to-Start (SS) dependency is a logical relationship in which a successor activity cannot start until a predecessor activity has started.
Finish-to-Finish (FF) Dependency
A Finish-to-Finish (FF) dependency is a logical relationship in which a successor activity cannot finish until a predecessor activity has finished.
Leads and Lags
A lead is the amount of time a successor activity can be advanced with respect to a predecessor activity. A lag is the amount of time a successor activity must be delayed with respect to a predecessor activity.
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