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Blog > What is a Work Breakdown Structure and why do I need one?

What is a Work Breakdown Structure and why do I need one?

affiché le 3 août 2017

by Maria Lahiffe

Be honest – how many times have you started in on a project with only a vague idea of where it was going to lead? How did that work for you? Did you end up having all the resources you needed in the end, or did you have to scramble part-way to make things work?

The Work Breakdown Structure (WBS) is a tool project managers use to formally establish all the work that will be needed to do a project. It is an important part of the planning phase of a project, which we discussed in a previous blog post. Specifically, the WBS is used to define the activities for the project. Once you have the WBS, you can look at what resources you’ll need and develop a schedule.

Why use a Work Breakdown Structure?

There are three compelling reasons why we recommend you create a WBS for your projects:

  1. It will help you to accurately and specifically define and organize the scope of the total project.
  2. It will help you communicate to the project team precisely what is expected at each stage of the project, to allocate resources and personnel appropriately.
  3. It will facilitate communication about the specifics of the project with stakeholders, like management, board, or end-users, to make sure nothing is overlapping or missing.

How do I create a Work Breakdown Structure?

Project Scope

Start with a clear statement of the project scope. “A good scope statement includes the following information:

  • Justification
  • Product scope description
  • Acceptance criteria
  • Deliverables
  • Constraints
  • Assumptions” [1]


The best people to have in the room when you create your WBS are the people who will be doing the work, and possibly some external stakeholders. You’ll need a blank wall and a lot of sticky notes.

  1. Top level: project title
  2. Second level: all the deliverables for the project. Write each one on a separate sticky note.
    Follow the 100% rule: 100% of the work for the project should be covered by the WBS. This is why you need to involve everyone in this process, to make sure nothing gets forgotten.
  3. Third level and beyond: break down the deliverables into successively smaller chunks of work. Each chunk is called a Work Package. Each work package is a piece of work which can be assigned to a specific person or team to complete. A rule of thumb is that a work package should take no less than 8 person-hours, and no more than 80 person-hours to complete.
  4. Before you finish the meeting: Step back a minute to check for gaps and overlaps. Make this a mindful step in the process, because when you are in step 3, it is easy to get lost in process details.

Here is an example of what a WBS may look like once you’re finished.


Common Pitfalls

Watch out for these when you create your WBS:

1.      Work Package Detail

This can be difficult to dial in. There needs to be enough detail that the person or team knows what is expected of them, but general enough that the person or team has the authority to decide the best way to achieve the deliverable.

2.      Focus on Deliverables, not Tasks

The WBS defines deliverables, i.e. what is meant to be accomplished. It is not a place to prescribe actual tasks.

3.      The WBS is not a Plan or Schedule

The WBS simply breaks down deliverables into workable chunks. Certainly, it can be used to develop a schedule, as well as to identify needed resources. However, the WBS itself is simply a breakdown of work.

4.      Document any changes to the WBS

No plan is ever written into stone. Changes happen. However, the WBS should be considered as a formal document which should be respected. Any changes should be documented and approved by the project manager, who can make sure that everyone affected by a change, knows about it.

A Work Breakdown Structure is a valuable tool to organize projects, to make sure that all of the needed work gets done, to ensure a high-quality result.

To learn more about applying the Work Breakdown Structure to your own projects, as well as many other aspects of project management, come to our upcoming seminar, taught by certified Project Management Professionals. The seminar cost includes up to 20 hours of individual one-on-one coaching at your location, a $5,000 value.

Want to learn more? Come to an upcoming workshop.

Click here for more information, and to register.

Volunteer Ottawa offers a comprehensive suite of courses related to organizational operations. Click here for more information, and to register. Subscribe to our Event RSS Feed to be among the first to know when a new workshop is added to the schedule.

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Related post:

[1] S. E. Portny, "What to Include in a Project Scope Statement," Dummies (A Wiley Brand), [Online]. Available: http://www.dummies.com/careers/project-management/what-to-include-in-a-project-scope-statement/. [Accessed 3 August 2017]. | M. Mathis, "Work Breakdown Structure (WBS) Purpose, Process, and Pitfalls," Project Smart, [Online]. Available: https://www.projectsmart.co.uk/work-breakdown-structure-purpose-process-pitfalls.php. [Accessed 2 August 2017].
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