Work Breakdown Structure

Work Breakdown Structure (WBS) looks at splitting deliverables into smaller components and then sizing each of them thereby providing the Project Manager with a way to provide a reasonable estimate for delivering the project.

The PMBOK defines Work Breakdown Structure as a deliverable-oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and create the required deliverables. It organizes and defines the total scope of the project. Each descending level represents an increasingly detailed definition of the project work. The WBS is decomposed into work packages. The deliverable orientation of the hierarchy includes both internal and external deliverables.

Steps to Create a WBS

Here are some simple points to keep in mind when creating a WBS.

  1. Ensure you have a list of deliverables for the project. You can get this from the proposal, contract or a scope document.
  2. For each deliverable create a list of sub-deliverables. PMI calls these work packages. Work packages define the amount of work that can be tracked by the Project Manager.
  3. For sizing the deliverables ensure you have the necessary experts working along with you. For each deliverable ask yourself questions like “How Long?”, “Who?”, “What next?”. This will ensure you have the relevant details captured in the WBS and are not missing out on anything.
  4. Many experts propose the 8/80 rule for creating a WBS, i.e., no tasks should be less than 8 hours or more than 80 hours. If it is greater than 80 hours, decompose them further into work packages of reasonable measure.

Advantages of a WBS

  1. A Work Breakdown Structure can help identify potential risks in a given project. If a WBS has a “branch”which isn’t well defined it potentially defines lack of clarity in the scope and hence lack in clarity on what deliverables are expected from that “branch”.
  2. If you are falling behind in your project, referring the WBS will quickly identify the  major deliverables impacted by a failing work package or late deliverable.
  3. A WBS used along with tools like MS Project can help identify gaps in your plan and also identify resources that are over-worked. It will help identify under-utilized resources and thereby act as an aid to create a well-balanced plan
  4. A well-defined WBS minimizes the chance of adding items outside the scope of work or forgetting a critical deliverable.

An Example

The image below shows a very simple WBS.

WBS Example

As you would observe:

  1. Each Task has been broken down into further sub tasks. If needed, these could be broken down further. Don’t forget the 8/80 rule described earlier though!
  2. Each Task/Sub-task has a unique identifier associated with it. This ensure there is consistency when referring to them
  3. A task can be marked as “Done”, once all its sub-tasks have been completed. Similarly, the Project can be marked as “Done” once all its Tasks have been completed.
  4. Even though Resource Name and Cost hasn’t been captured in the above example, one could have done that too. When using tools like MS Project, one would typically assign the name of resource working on it.

Here’s a good video summarizing all we have captured so far.


Share your experiences in using WBS in the comments below. Don’t forget to read the post regarding Software Estimation Techniques.

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About the Author: Anuj Seth

Anuj is a certified PMP with over 20 years of Software Development and Management experience. He founded PM Tips in 2020. Contributors are welcome. Drop him a note via the Contact page.

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