Using Decomposition in Work Breakdown Structures

The work breakdown structure is a hierarchical chart allowing the project team to view at a glance the work needed to complete a project. Good work breakdown structures function as the project team’s task list. For an excellent overview of the work breakdown structure, see Ann Gordon’s series, “What is a Work Breakdown Structure" and Lucinda Watrous’ article “The role of the WBS in the Project Planning Lifecycle Explained.”

If tackled properly decomposition is the prerequisite to an outstanding work breakdown structure. When you reach the stage of creating the work breakdown structure, all project deliverables and major tasks should be decomposed into work packages. Creating the work breakdown structure, should flow quickly, because tasks have already been broken down in a hierarchical manner.

The project objective should be listed at the top of the page, as this is the ultimate desired outcome of all of this work. Underneath it, link each deliverable and major task. Assign each deliverable a code – either a letter or a number. Every task item and work package that is listed underneath the deliverable will contain this code as the first part of its own code.

When the WBS is completed, it should contain every work package created during the decomposition phase, with a code reflecting the hierarchy. Each work package should have its own code, budget, and estimated duration. If you followed part three of this series, you will have decomposed each deliverable on its own sheet of paper. Double check to ensure that everything on that sheet of paper is represented underneath the deliverable listed in the WBS.

In an Ohio State University – Office of the CIO document introducing readers to the framework of the WBS, six criteria for Work Breakdown Structure completeness are given. These criteria are:

1. The status of the work package is measurable. The task is adequately defined, and when questioned, the exact status can be given.
2. Events involving the start and end of action items are defined in a clear manner.
3. All activities include deliverables. Action items should be clearly linked to a product that will be completed once the activity is completed.
4. Duration and cost are easily estimated.
5. The duration of an activity follows the 8/80 rule. No work package should be less than eight hours nor should it be more than 80 hours.
6. Work packages are independent of one another. Once work has begun, it can continue until complete. Dependencies are noted, and a task that has begun should not stall because it has everything it requires contained within it.

If all six of these criteria have been met, then decomposition has produced a successful work breakdown structure. If one of these criteria has not been met, go back, and decompose your deliverables or arrange work packages until they meet the requirements.