Building a Work Breakdown Structure (WBS)

Work Breakdown Structure (WBS)

A Work Breakdown Structure (WBS) is a key project deliverable that organizes the team's work into manageable sections. The Project Management Body of Knowledge (PMBOK) defines the work breakdown structure as a "deliverable oriented hierarchical decomposition of the work to be executed by the project team." The WBS visually defines the scope into manageable chunks that a project team can understand, as each level of the work breakdown structure provides further definition and detail. An easy way to think about a Work Breakdown Structure is as an outline or map of the specific project.

The project team creates the project Work Breakdown Structure by identifying the major functional deliverables and subdividing those deliverables into smaller systems and sub-deliverables. These sub-deliverables are further decomposed until a single person can be assigned. At this level, the specific work packages required to produce the sub- deliverable are identified and grouped together. The work package represents the list of tasks or "to-dos" to produce the specific unit of work. If you've seen detailed project schedules, then you'll recognize the tasks under the work package as the "stuff" people need to complete by a specific time and within a specific level of effort.

From a cost perspective, these work packages are usually grouped and assigned to a specific department to produce the work. These departments, or cost accounts, are defined in an organizational breakdown structure and are allocated a budget to produce the specific deliverables. By integrating the cost accounts from the organizational breakdown structure and the project's Work Breakdown Structure, the entire organization can track financial progress in addition to project performance.

Why use a Work Breakdown Structure?

The Work Breakdown Structure has a number of benefits in addition to defining and organizing the project work. A project budget can be allocated to the top levels of the Work Breakdown Structure,  and department budgets can be quickly calculated based on the each project's work breakdown structure. By allocating time and cost estimates to specific sections of the Work Breakdown Structure, a project schedule and budget can be quickly developed. As the project executes, specific sections of the Work Breakdown Structure can be tracked to identify project cost performance and identify issues and problem areas in the project organization. 

Project Work Breakdown Structures can also be used to identify potential risks in a given project. If a WBS has a branch that is not well defined then it represents a scope definition risk. These risks should be tracked in a project log and reviewed as the project executes. By integrating the Work Breakdown Structure with an organizational breakdown structure, the project manager can also identify communication points and formulate a communication plan across the project organization.

When a project is falling behind, referring the Work Breakdown Structure will quickly identify the major deliverables impacted by a failing work package or late sub- deliverable. The Work Breakdown Structure can also be color coded to represent sub- deliverable status. Assigning colors of red for late, yellow for at risk, green for on-target, and blue for completed deliverables is an effective way to produce a heat-map of project progress and draw management's attention to key areas of the Work Breakdown Structure.

Example of Work Breakdown Structure: