What Is A Work Breakdown Structure In Project Management?
A work breakdown structure (WBS) is a way to visualize an entire project’s tasks, phases, and deliverables.
Here’s the hard truth: crafting a WBS is one of the hardest project planning tasks, but one of the most important to get right. It will help you identify the activities that are required to complete a project and organize those activities into manageable chunks of work.
What Is A Work Breakdown Structure (WBS)?
A work breakdown structure is a resource planning visualization that outlines a project’s deliverables and components. It helps stakeholders to understand what work is part of project delivery. Work that isn’t in the WBS isn’t in the project.
Here are some more details, courtesy of The Project Management Body of Knowledge (PMBOK) Guide:
“The WBS is a hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables. The WBS…represents the work specified in the current approved project scope statement”.
Here’s what it often looks like:
As you can see, the WBS is a hierarchy of things that the project will produce, usually two to four levels deep. It also shows how individual tasks are related to one another by highlighting task dependencies.
Before we go into further detail, here are some definitions of terms that I’ll use in this article:
- Baseline: An initial estimate of the scope of work required to deliver a project
- Milestone: Delineates an important point in a project schedule (ex. completion of a major phase of work or a key decision point)
- Critical Path: The sequence of stages that determines the minimum time needed for an operation
How Detailed Should The Work Breakdown Structure Be?
A WBS decomposes larger chunks of project work into smaller tasks. But, what’s the right level of detail to break down?
Like Goldilocks, you want to seek a happy medium. Too much detail, and your WBS will be unwieldy and difficult to manage. Too little detail, and your WBS will lack the information you need to manage your project successfully.
Aim for three levels of detail in your WBS, but no more than four levels. Like with other project management documentation, how you craft your WBS will vary based on organizational best practices and whether you’re running a complex project.
Components Of A Work Breakdown Structure
Here are some items you’ll need to include in your work breakdown structure:
- Deliverable: A tangible or intangible good or service produced as a result of a project that is intended to be delivered to a customer (either internal or external)
- Control Account: The work assigned to one organizational unit within the WBS; used for budgeting and reporting purposes
- Planning Package: An organizing unit that describes a group of related tasks underneath it (the work package)
- Work Package: An organizing unit within a WBS that groups together a set of related activities
- WBS Dictionary: Includes additional details about each element that comprises the WBS
The deliverables (or phases in some cases, as I’ll explain in the next section), control accounts, planning packages, and work packages are plotted like the below example.
Interpreting a WBS can be challenging given the many moving parts that go into successful activity mapping. This is where a WBS dictionary comes in handy—it defines each WBS element and how it’s used.
Here’s an example of a WBS dictionary (see the corresponding WBS below the table).
| Column | Description/Use |
|---|---|
| WP1 | A high-level view of the tasks related to a specific work package. Numbering or otherwise distinguishing the work packages makes it easier to refer to them in meetings or status reports. |
| WP | The sub-task related to the high-level work package. I would recommend creating sub-tasks to represent a level of effort of four hours or more. |
| Work Package Number and Name | A description of the work package |
| Task | A description of the task to be performed as part of this work package |
| Name | The person assigned to perform this task. Ideally, you should only have one responsible person listed here. You want to be able to make sure that you have someone accountable for each task. |
| Input/Output | What is the input to or output from this activity? Is the activity associated with a specific deliverable? |
| Effort | How much effort does it take to complete the task (measured in days)? Calculate the effort associated with this task in collaboration with your team and make sure that the person performing the task agrees with the assessment. |
| Check | Includes a formula to verify that resources are not overallocated |
| Wk1/2/3, etc. | The calendar week in which the task takes place |
2 Types Of Work Breakdown Structure
It’s worth noting that there are two ways of creating a WBS—either most commonly with deliverables or alternatively by project phases.
- Deliverable-oriented work breakdown structure: Also known as entity-oriented, noun-oriented, or product-oriented. This is most common.
- Phase-based work breakdown structure: Focused instead around the tasks required to complete those deliverables. The other names for this that you might come across are activity-oriented, task- oriented, verb-oriented, or process-oriented.
Why Should You Use A Work Breakdown Structure?
The WBS’s detailed view of a project clarifies the work that each team member is expected to complete. Without the work breakdown structure, it is likely that the team will miss requirements, and further likely that the deliverables and maybe even the entire project will miss the mark.
The WBS visualizes project outcomes, the sequence of required activities, and project deliverables. Within the WBS, organizing mechanisms like the control account help you bill to clients, while the work packages break down exactly what is included in the project scope.
Here are some key reasons why you should use a work breakdown structure:
1. Increases Clarity around Roles and Responsibilities
Since the WBS delineates tasks and assigns them to individuals, the team learns who is responsible for which aspect of work and when deliverables are due.
More importantly, project team members understand how their work contributes to meeting each deliverable and, ultimately, the project goals. This boosts motivation and engagement.
2. Helps Ensure Tasks Are Completed Properly and on Time
The WBS dissects deliverables down to the lowest level of detail, making it more likely that no task or sub-deliverable is lost in the process. The breakdown process reduces ambiguity and confusion around what each team member is required to do and when they need to have their work completed.
3. Enables Activity Tracking
The WBS creates an identifiable baseline. The ability to track activities against the baseline increases the chances that the project progresses as expected.
The graphic below shows the required inputs to create a work breakdown structure and the outputs it generates, including a scope baseline and updates to requirements documentation.
Project managers that fail to include the necessary inputs or try to skip this step are more likely to encounter issues later in the project life cycle.
Work Breakdown Structure Template
To get you started, here is a free downloadable WBS template. To edit the file, download it as an XLSX file and use it within Google Sheets or Excel. The file also includes a sample WBS that you can use as a model.
How To Create A Work Breakdown Structure
Now that we’ve reviewed some WBS examples, how do you begin creating a WBS on your own? Here are some steps to consider when creating a work breakdown structure:
- Identify project deliverables. Make sure that you include each deliverable so that the team has a comprehensive picture of what work is required.
- Break down the deliverables into smaller chunks of work, ie. the tasks that are required to produce the deliverable. Continue breaking down your tasks until you reach a point where they are manageable (a good suggestion is to use work increments of four or more hours.)
- Once you have a high-level overview of deliverables and supporting tasks, work with your team to realign the tasks into a sequence for when the activity should be completed.
- In step 2, you listed tasks that were estimated to require four hours or more of work. At this stage, refine your estimates to ensure that you’ve assigned a level of effort to each task in your WBS.
- Schedule the tasks based on the sequence and expected level of effort. This means assigning dates for when you expect to work on each task so that you can meet deliverable deadlines.
- Review project staffing to make sure that you have a realistic plan based on the resources that are available. It’s important to clearly identify the tasks along the critical path that must be completed for your project to move forward. Managing resources effectively is a tricky art to refine.
- Review the completed plan with your team to gain buy-in.
5 Best Practices For Creating A Solid Work Breakdown Structure
Here are some best practices to keep in mind that will help you create a good work breakdown structure:
1. Take Time to Understand your Inputs and Outputs
For a WBS to be effective, it needs to reflect an understanding of project goals and objectives and what is required to achieve those objectives. Before you begin crafting your work breakdown structure, it is a good idea to review the project charter/statement of work documents as a basis for the key deliverables.
You could then use sticky notes to plot out the high-level deliverables, with different colors to represent different components of the task. You could also use resource management software or a project management software to socialize the plan with your team, assign team members to tasks, and gain buy-in from your team in a remote setting. Visualizations are a great way to encourage the team to think about the sequence of activities and what’s involved.
2. Take Advantage of Subject Matter Experts
Use subject matter experts to assist in planning and sequencing tasks and activities. You can make sure tasks are ordered correctly and that there is no overlap between components of your WBS.
3. Gather Feedback
Review your work breakdown structure against available resources to make sure that your plan is realistic. This may require consulting with other project managers, the leadership team, and/or a resource manager.
4. Get Buy-in
If your team doesn’t agree with the task estimates in the WBS, then you won’t be successful executing against it. Make sure you take the time to review the work breakdown structure with your team to promote alignment and accountability.
5. See the Forest for the Trees
Don’t make the WBS too detailed, as it will become too cumbersome to update. As mentioned above, it’s best to stick to increments of work that are four hours or more.
Frequently Asked Questions about Work Breakdown Structures
Should I Use a Work Breakdown Structure or a Gantt Chart?
Like most things, the answer is: it depends.
When To Use A WBS
A WBS breaks down what you are building into smaller, more manageable components. It shows what work you are doing on a project. Therefore, the WBS is useful for scope control, including change management.
When To Use A Gantt Chart
By contrast, a Gantt chart shows when you are doing the work. Use your WBS as the basis for your Gantt chart to track tasks across time. The Gantt chart shows the start and finish date of each task, their dependencies, and their relationship to each other. You use a Gantt chart for schedule control.
Are a WBS and the Critical Path Method the Same Thing?
The critical path is the list of core project activities that must be completed to deliver the project within the triple constraints (time, budget, and scope.) If the critical path slips, then your project will see an adverse impact in one of these three areas.
The WBS hierarchically organizes project activities and deliverables, not just the critical path activities.
When in the Project Life Cycle Should I Create the WBS?
It’s important to create the WBS during the project planning phase, as it helps you gain understanding of the work required to execute the project. The WBS is also a key input into the project schedule, budget, and risk management plan, all of which are needed earlier in the project life cycle.
What’s Next?
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