The Work Breakdown Structure: An Essential Project Management Tool

Updated November 21, 2019

Tackling a large or complex project can prove overwhelming. Whether it’s coordinating an industry event, launching a new product, or starting a business, any project with multiple parts or people can quickly miss deadlines or exceed budgets.

To achieve success, you must understand project management basics. What’s more, these types of projects require a map to the project goal, one that captures considerations such as how long it will take, cost concerns, and a clear path to completion.

That’s where the work breakdown structure in project management comes in. It is a key element to any project management plan.

Overview: What is a work breakdown structure?

The work breakdown structure, or WBS, is one of the project management steps in the planning process of a project life cycle.

According to Smartsheet, the WBS concept was developed by the U.S. Department of Defense (DOD) and National Aeronautics and Space Administration (NASA) in the 1950s and 1960s as a means of completing projects like the Polaris missile program.

The WBS documents the tasks involved in completing a project and breaks those down into digestible chunks of work so that the people engaged in the project can address the tasks more efficiently. By completing all the tasks, the team achieves the project goal.

What are the characteristics of the work breakdown structure?

The WBS is an effective tool for large or complex projects composed of many tasks and requiring weeks or months of work involving several people.

Before creating a WBS document, it’s critical to understand the characteristics of one. Every WBS should adhere to certain design principles in order to be effective.

1. The tree hierarchy

A common characteristic of the WBS is that it uses a tree structure as a visual representation of the project.

At the top of the tree is the fully completed project. All the components that must be done to achieve the final outcome are listed below this.

Each component of work is then broken down into sub-components, which are also broken down even further. This process continues until you are left with a task that cannot be broken down any further. These final tasks are called work packages.

Sample work breakdown structure using construction of a house as an example, broken down into subtasks

An example of a work breakdown structure’s hierarchical composition. Source: workbreakdownstructure.com

They sit at the lowest level of the tree and represent the work that is assigned to team members on the project.

This diagram illustrates the WBS tree structure. Note how each level of the hierarchy is numbered using a sequential decimal system. This helps anyone looking at a specific task to know where it sits in the hierarchy.

2. The 100% rule

The 100% rule is a key element of the WBS. This rule requires that the WBS diagram includes every piece of work required to meet the project goal.

In addition, adding up all the tasks at each level of the hierarchy should equal 100% of the work for that level.

The tasks on the tree should include both critical path items — those parts of the project that are essential to complete in a specific order — as well as elements that can be delayed or done in parallel without compromising deadlines or budgets.

3. Focus on outcomes, not actions

When building the tree diagram, it’s crucial that the tasks focus on specific outcomes that will be delivered, not actions. By doing so, the WBS communicates what a desired result looks like, enabling the people working on each task to know what is expected of them.

As a result, each piece of work on the tree should be unique, that is, mutually exclusive. No two tasks should be identical. This avoids duplication of effort.

Benefits of using a work breakdown structure

The work breakdown structure offers several benefits. Aside from organizing the work on a project, some of the benefits of a WBS are:

  • Improved efficiency: By dividing the project into smaller components and defining the outcomes, it’s easier to make progress because the steps required for project completion are outlined and the team knows what’s expected of them, resulting in greater efficiency.
  • Realistic timelines: Because all required tasks are cataloged, a project completion timeline can be more accurately calculated. This helps the team avoid unrealistic deadlines and identifies the tasks that can be done in parallel.
  • Easier progress tracking: The WBS simplifies tracking project progress. As each component is completed, it’s straightforward to compare what’s done with the work left to do. For example, if a project is broken down into 10 tasks and 4 are completed, it’s clear to see that 60% of the project remains.

How to create a work breakdown structure

Now that we’ve covered what a work breakdown structure is, its benefits, and what it’s comprised of, it’s time to look at the steps to creating a WBS.

1. Meet with the SMEs

When it comes to creating the actual WBS document, the first step is to meet with the project’s subject matter experts (SMEs).

These are the people with specialized or in-depth knowledge about the various parts that comprise the project. The SMEs help identify the various tasks required for the WBS.

For example, if you are building a software product, you would need to consult with the engineers who code the software to determine the tasks involved and an estimate of how long each piece of coding will take.

Pro Tip: Cast a wide net when engaging project SMEs. Try to get input from as many people as possible. This allows for capturing different viewpoints and considerations in order to get as complete a picture as possible for the WBS.

2. Perform a critical path analysis

The next step is to execute a critical path analysis. This process identifies those tasks that must be completed sequentially.

It’s an important step because the critical path items determine how long the total project will take, since one task cannot start until the previous task along the critical path is completed. This is different from other tasks in the WBS that could be completed at the same time, or in parallel, to the critical path items.

Pro Tip: In the WBS documentation, it’s useful to mark the critical path items in some way to help them stand out from non-critical-path tasks. This can be done by color coding them or flagging them with a special icon. Also, note the order in which the critical path items must be completed.

3. Document the WBS

Once the tasks necessary to achieve the project goal are identified, it’s time to apply the WBS template and put the tasks into a tree structure. You may choose from many approaches to accomplish this.

One method is to use project management software. Many packages are on the market with varying prices and features to meet just about any need.

For instance, software like monday.com supports many of the requirements of a WBS template, including time tracking and budget features.

If specialized software is not an option, it’s possible to cobble together the WBS in a spreadsheet or on slides. This approach typically requires more time to perform updates to the plan than using project management software.

Another approach is to use sticky notes. Each note would represent a task in the project and would be organized in the WBS tree structure on a wall or whiteboard so that members of the team can see the WBS. Here’s what that might look like:

Pro Tip: The WBS should be documented in a way that’s easy for all team members to access. So if specialized project management software is the preferred option, all team members should have access to that software or at least be able to view the latest WBS version at any time.

Final advice for work breakdown structure newbies

While the work breakdown structure is a valuable tool in a project manager’s arsenal, keep in mind that the WBS should be a living document. It is meant to change and evolve as the project progresses.

Also, be sure to hold regular review sessions. These sessions help ensure the team is on the same page, and serve as a forum to raise new challenges or adjustments to the WBS. Remember that the WBS serves the needs of the team, and these sessions present opportunities to shape it accordingly.

It takes effort and planning to create a WBS. But creating a work breakdown structure will help you conquer even the most daunting projects.

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