Work Breakdown Structure

Used by the project management team to organize and define a project into manageable objectives and create a blueprint by which the steps leading to the completion of a project are obtained. It is an outline of the project that becomes more detailed under the subheadings or work packages.

A hierarchically-structured cost estimating framework or format that organizes and classifies the extent of a real property asset. Each descending level represents an increasingly detailed definition of the asset. [adapted from NISTIR 6389, UNIFORMAT II Elemental Classification for Building Specifications, Cost Estimating, and Cost Analysis] A real property asset may contain:

a. Component. A single item or small piece of equipment that performs a distinctive and necessary function in the operation of an assembly. Components are usually removable in one piece and are considered indivisible for a particular purpose or use.

b. Assembly. A grouping of individual work items, components, or subassemblies, with appropriate quantities, to provide a basis for cost estimating.

c. System. A collection of assemblies that performs a given function regardless of the design specification, construction method, or materials used. Examples are: mechanical, electrical, plumbing, and fire protection systems.

A WBS dictionary defines the work scope for each element in the WBS. The WBS is used as the basic building block for the planning of all authorized project work. The WBS is a product-oriented division of project tasks depicting the breakdown of work scope for work authorization, tracking, and reporting purposes, which facilitates traceability and provides a control framework for management. It should ensure that the work scope is entirely covered and allow for the integration of technical, schedule, and cost information.

The WBS also facilitates communications as it establishes a common frame of reference for customers, management, and IPTs. A WBS is a direct representation of the work scope in the project, documenting the hierarchy and description of the tasks to be performed and their relationship to the product deliverables. The WBS breaks down all authorized work scope into
appropriate elements for planning, budgeting, scheduling, cost accounting, work authorization, measuring progress, and management control. The WBS should be extended to the level necessary for management action and control based on the complexity of the work. Each item in the WBS is assigned a unique identifier. These identifiers should provide a structure for a
hierarchical summation of costs and resources.

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.

A breakdown of a project into those subelements that define the project. The WBS provides a consistent organization framework throughout the project.