Work breakdown structure


Work breakdown structure - Definition

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

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 management tool. Many United States government statements of work require work breakdown structures.

Contents

How to build a WBS

Whether the WBS should be activity-oriented or deliverable-oriented is a subject of much discussion (http://www.maxwideman.com/musings/wbswar.htm). 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, to state the obvious:

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:

short-term memory capacity is limited to 5-9 items.
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.
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