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Work Breakdown Structure

What is a Work Breakdown Structure? Definition and meaning

In a work breakdown structure (WBS), the project is graphically represented divided into sub-projects and work packages. Here, sub-projects must be broken down further, while work packages represent the lowest level that cannot be divided any further.

The work packages contain the tasks that are needed for further planning.

Structuring principles of a work breakdown structure

Three principles have become established for structuring a work breakdown structure. They determine the criterion by which the project is broken down into sub-projects and work packages:

  • Object-oriented structuring: The work breakdown structure is built around the objects or components of the end product, for example assemblies, components or subsystems.
  • Function-oriented structuring: The structure follows the functions or types of activity in the project, such as planning, design, implementation and testing.
  • Phase-oriented structuring: The work breakdown structure is based on the timeline and organises the project by project phases.

In practice, these principles can also be combined (mixed structuring), for example object-oriented at the upper level and function-oriented at the lower levels.

Methods of the Work Breakdown Structure

A work breakdown structure (WBS) can be created using three methods:

Top-Down Method

With the Top-Down method, work breakdown structures are represented from the project level down to the detail (deductive approach).

Bottom-Up Method

With the Bottom-Up method, work breakdown structures are represented from the detail up to the whole project (inductive approach).

Yo-Yo Method

In the Yo-Yo method, the deductive (Top-Down) and the inductive (Bottom-Up) method are combined in alternating steps in order to use the advantages of both approaches.

The WBS is usually depicted graphically in a vertical or horizontal tree structure. It is important that the goals and steps are presented clearly and in an easily understandable way. An alternative way of representing it is, for example, the bar chart / Gantt chart.

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Frequently asked questions

What belongs in a work breakdown structure?
A work breakdown structure divides the project into sub-projects and work packages. Sub-projects can be broken down further, while work packages form the lowest level that cannot be divided any further. They hold the tasks that are needed for the ongoing planning.
Which methods are there for creating a work breakdown structure?
A WBS can be created using the Top-Down method (from the project down to the detail), the Bottom-Up method (from the detail up to the whole project) or the Yo-Yo method, which alternates between both approaches.
What is the difference between the Top-Down and Bottom-Up method?
With the Top-Down method, the work breakdown structure is refined step by step, starting from the overall project down to the individual work packages (deductive approach). With the Bottom-Up method, the individual work packages are gathered first and then combined into the overall project (inductive approach).
By which principles is a work breakdown structure organised?
A work breakdown structure can be organised object-oriented (by the components of the end product), function-oriented (by types of activity) or phase-oriented (by project phases). In practice, these principles are often combined.
How do I create a work breakdown structure in software?
With the work breakdown structure from projectfacts, you structure your project clearly into sub-projects and work packages and display it as a tree structure.