September 11, 2018

Work Breakdown Structure Tutorial and WBS Example

What is a work breakdown structure?


A Work Breakdown Structure, or WBS as it is commonly known, is the backbone of the scope of a project and is used to assist in the planning phase of the project, being an important input towards scope definition which in turn will lead into the development of the project schedule.

work breakdown structure example
Work Breakdown Structure Example
The WBS is an exercise of decomposition, where the project is broken down from key deliverables into smaller, manageable chunks of work, called work packages. It is therefore deliverable-orientated and is usually represented as a hierarchical tree, where parent (higher level in the WBS) and child tasks are clearly distinguishable, making it easier to assign estimates and responsibilities.

How to Create a Work Breakdown Structure?

Level by level – see the illustration below: 

how to create a work breakdown structure
How to Create a Work Breakdown Structure
  1. The first level of the WBS will be the project itself. As an example, consider the building of a house, where “New House” would be your end product for the project, typically designated as parent task 1, that is, “1 New House”.
  2. We now start decomposing the project into smaller components, their deliverables. If we think of a house, our next level would be key areas such as the “Foundation”, “Structure”, “Interiors” and, of course, “Project Management”. These are represented by building a new lower layer in our tree structure and by assigning an individual code to each, that is, “1.1 Foundation”, “1.2 Structure”, “1.3 Interiors” and “1.4 Project Management”.
  3. We continue one step further, now decomposing each of the deliverables previously identified into their subcomponents. For instance, “1.2.2 Structure” could be broken down into “1.2.1 Walls”, “1.2.2 Electrical”, “1.2.3 Plumbing”, and “1.2.4 Mechanical”. I’m no expert in construction but I’m certain you can see my point here.
  4. We then add as any other additional layer as needed in our tree until we reach that level where we have work packages. A work package is the lowest level of a WBS. You know you have arrived at the work package level when the work involved can be accurately estimated and managed by one person. The work package can then be decomposed into activities for inclusion on the project schedule. Let’s take the example of the electrical part in the house’s structure. In our example, the work packages would be “1.2.2.1 Do electrical cable work”, “1.2.2.2 Procure light fixtures”, “1.2.2.3 Arrange for electricity contract”, etc.

Hints and Tips

  • Follow the 100% rule: if it is part of the scope, it needs to be in the WBS; if it is not in the WBS, then it is not part of the project’s scope.
  • Consider the 8-80 rule: it can be trick to find when to stop, what is the right level of detail. To help you, consider this simple and easy to remember rule of thumb. If the task has less than 8 hours, it is likely to detailed and you will end up micro-managing, therefore, it could be aggregated to others as work package; if the task is bigger than 80 hours of work, it is likely to high-level to be manageable and assignable, hence you might want to break it down further
  • Use the right nomenclature: to avoid confusions, apply a defined convention for the WBS. Use nouns for deliverables (level 2) and verb infinitive tense for work packages, instilling a sense of action.
  • Apply the rolling wave technique: when the scope is not fully known at the beginning of the project, the rolling wave planning technique is handy. It involves progressive elaboration to add detail to the WBS on an ongoing basis, where more detailed planning is put for short term than long term work items, which are based on high-level assumptions. That is, this technique enables you to plan for a project as it unfolds.
  • Complement it with a WBS Dictionary: the accompanying friend of the WBS, the WBS Dictionary is a document that provides detailed information about each component in the WBS, namely scheduling considerations and constraints, resources required or even quality expectations for that WBS element.

The more complex the project, the more use you will find in building a WBS and, while it might look daunting at first, it is an essential tool for getting a project off the ground. After all, the best way to complete a big task is to complete each of their related sub tasks, one at a time and you will get it completed in no time.


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