In project management, a Work Breakdown Structure is a document that illustrates all the components of a project. Its not a flowchart: rather, its a document that breaks down a project into smaller, more manageable sections so that a project manager can better assess what costs and resources he needs.
In order for a WBS to be effective, it needs to have the following things:
100% of Deliverables
A WBS needs to cover everything needed for project completion. Everything. If youre going to properly estimate the work required (and therefore your timeline), you cant afford to leave anything out. Ideally, the sum of all the work involved in the lower levels of the WBS should equal 100% of the work required at the upper levels.
For example, if 20 hours are estimated for a level 2 task (e.g. stage props), then the total hours of the level 3 tasks under stage props should add up to 20 hours too. This kind of consistency is important if you want to create an accurate project plan.
A WBS dictionary is more than just a definition of terms. Its also a reference for each component of the Work Breakdown Structure and contains milestones, deliverables, tasks, costs, etc. In a way, you could consider it the micro view of the elements in the WBS, with all relevant project information, with the WBS itself being the macro overview.
Clear Hierarchy of Elements
What the WBS does is work backwards from the final result. Each breakdown creates another hierarchy level, which in turn are broken down into another layer of component parts.
For example, a bed (level 1) can be broken down into a mattress and bed frame (level 2). The mattress can then be broken down into the mattress cover, springs, and stuffing (level 3).
The minimum level of detail
While a complete WBS hierarchy is important, it shouldnt be too detailed. Otherwise, youd just waste time describing minor elements that people can easily figure out for themselves.
There are many rules of thumb to gauge the right threshold, but it all boils down to your familiarity with the project, and if it makes sense to boil things down any more. I can, for example, have the final level of a cooking recipe stop at chop carrots, and not need to describe every single stroke of the knife.
One final thing to remember is that the WBS chart describes deliverables, not tasks. This way, the project team has the freedom to figure out the best approach.
Work Breakdown Structures are a great aid in producing accurate project scopes, and its worthwhile to include one in every project if youre not doing so already.