Work/Cost Breakdown Structure (WBS/CBS)

The Work Breakdown Structure (WBS) is an outline for the project’s Scope of Work and provides a numerical structure for organizing, sorting, and filtering the schedule and cost data for reporting purposes. A Work Breakdown Structure (WBS) provides the foundation matrix to relate the elements of scope, responsibility, schedule and cost.

The WBS is a task-oriented, detailed breakdown that defines the code structure for tasks at a level on and above that typically defined in Critical Path Method (CPM) schedules. The WBS initiates development of a responsibility matrix known as the Organizational Breakdown Structure (OBS), and a resource-based Cost Breakdown Structure (CBS). It also provides the outline and foundation for scheduling, earned value management, and progress reporting on cost and schedule. 

Each element in the WBS is usually followed by a WBS narrative describing the effort required to accomplish the work. The WBS narrative often results in the project statement of work (SOW).