WORK BREAKDOWN STRUCTURE

In project management, a work breakdown structure (WBS) is an exhaustive, hierarchical (from general to specific) tree structure of tasks or deliverables that need to be performed in order for a project to be completed.

The purpose of a WBS is to identify terminal elements (the actual items to be done in a project). Therefore, WBS serves as the basis for much of project planning.

Work breakdown structure is a very common project managemet tool. Many United States government statements of work require work breakdown structures.

How to build a WBS

Whether the WBS should be activity-oriented or deliverable-oriented is a subject of much discussion. There are also various approaches to building the WBS for a project (see e.g. How to Build a Work Breakdown Structure below). Project management software, when used properly, can be very helpful in developing a WBS, although in early stages of WBS development, plain sticky notes are the best tool (especially in teams).

An example of a work breakdown for painting a room (activity-oriented) is:

• Prepare materials
  • Buy paint
  • Buy a ladder
  • Buy brushes/rollers
  • Buy wallpaper remover
• Prepare room
  • Remove old wallpaper
  • Remove detachable decorations
  • Cover floor with old newspapers
  • Cover electrical outlets/switches with tape
  • Cover furniture with sheets
• Paint the room
• Clean up the room
  • Dispose or store left over paint
  • Clean brushes/rollers
  • Dispose of old newspapers
  • Remove covers

The size of the WBS should generally not exceed 100-200 terminal elements (if more terminal elements seem to be required, use subprojects). The WBS should be up to 3-4 levels deep. Each level should be 5-9 elements broad. These suggestions derive from the following facts:

1. short-term memory capacity is limited to 5-9 items.
2. having fixed time to plan a project, the more terminal elements you have, the less time there is to pay attention to any single one of them. Consequently, your estimates are less thought-through.
3. the more terminal elements you have the more there are potential dependencies among them (see fact 2 above for consequences).

Books

• Carl L. Pritchard. Nuts and Bolts Series 1: How to Build a Work Breakdown Structure. ISBN 1890367125
• Project Management Institute. Project Management Institute Practice Standard for Work Breakdown Structures. ISBN 1880410818
• Gregory T. Haugan. Effective Work Breakdown Structures (The Project Management Essential Library Series). ISBN 1567261353

See also: project planning, critical path, critical chain, product breakdown structure.