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Estimate Better with a Work Breakdown Structure (WBS)

Projects are made up of hundreds, sometimes thousands, of tasks. It’s overwhelming, even for an experienced project manager, to keep everything straight. A step is missed, deliverables are delayed and a scramble ensues, it happens all the time. And that’s why the work breakdown structure (WBS) exists, to untangle the knots that cause project confusion. The WBS is a document that breaks down project scope, improves time estimation and provides more control over project execution. It’s a visual aid that’s used in the early stages of a project to expose the details; a WBS can be a project manager’s saving grace.

The work breakdown structure is a roadmap, a visual aid decomposing the pieces of a project. Simply stated, a WBS divides projects into manageable chunks of work that can be better estimated and controlled. It helps even the most complicated undertaking feel possible. A housing construction, for example, requires hundreds of small steps but can be divided into foundation, internal and external development. And, from there, “internal work” can be further refined into tasks like electrical and plumbing while “external work” includes building finishings, roofing and more. You might be inclined to skip the WBS—you’re busy assembling a team, drafting your schedule and defining your budget. But you, and your teammates, will be better off taking a WBS into the throes of project management battle.

Creating a work breakdown structure…

Widely considered the most important process in Scope Management, WBS definition demands a few inputs including: organizational process assets, requirements documents and the project scope statement. That means you’ll use your company’s WBS template, if it exists, along with the scope of work and any early requirements to create the work breakdown structure diagram.

The highest level of every WBS is the final deliverable—a commercial building, a video game, an airplane, whatever. You’re given some flexibility with the next level. Some project managers visualize the work by deliverable—artwork, scripts, source code, test plans—while others prefer phases—design, construction, testing. So create the second level of the WBS in the way that best fits your style and project. If you’ll create multiple user guidance documents, add a box for that deliverable. Also, create one for project management itself because, as you know, a lot of tasks go into keeping the project organized and on track. The third layer of the WBS further breaks down those phases or deliverables. For example, the design phase might not be granular enough so sub-level boxes for packaging design and product design are added. And now we come to the most crucial part of a work breakdown structure, the work package.

Each work package is a unit of work—create a test plan, find test scenarios, execute the test plan—that rolls up into one of the deliverables or phases in the WBS. Take each deliverable and decompose it into actual work. One deliverable in publishing a comic book is to create the artwork. But that’s too amorphous to be a work package so it’s decomposed further. Create a storyboard, sketch the characters, draft background scenery, finalize the order of the storyboard. Identifying these lower level pieces of work make the WBS whole and help you identify gaps in your project plan. The end result will look much like your company’s org chart, swapping the CEO for the final product, senior management for deliverables or phases, and employees for work packages.

The finer points of a work package…

The work package is the heart and soul of a WBS. Each one is a singular piece of work, duration and cost. So it needs a bit more detail than simply a box and a general description. Pair your WBS with a dictionary that will help you keep everything straight. Each entry in the WBS dictionary includes:

  • Work Package ID and Name—a unique identifier
  • Statement of Work—what’s the goal of this piece of work
  • Responsible Party—which team owns the work
  • Milestones—what deadlines are associated with the work package
  • Quality Requirements—what does it need to accomplish
  • Resources and Cost Estimates—who is needed and how much will it cost 

Once the work breakdown structure is done, put it to good use…

The WBS is done (phew!) and it might feel easy to check off that box, store the document away and move on to the next thing. But don’t do that, the WBS is a useful piece of the puzzle. Use it to create a scope baseline, a document that’s a combination of the WBS, the WBS dictionary and the scope statement. It sets a control for the project so you can look back and see what has gone according to plan and what has needed major or minor changes along the way. This effort will challenge you to be an efficient and thoughtful leader. And it will keep you honest—quality and ethics matter in every decision you make.

The work breakdown structure will visually map out your project from start to finish, first shovel to final coat of paint. It positions you to better estimate the number, and kinds, of resources needed to accomplish your goals. And it aids the definition of a more accurate budget. Not every project demands a WBS but each one benefits from its creation. It’s a step the best project managers don’t skip.