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A Project Manager’s Guide To Work Breakdown Structure

 

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If you’re a project manager, one of the first things that you learn about is a work breakdown structure (WBS), but creating one that brings value to your project is a lot harder than many project managers expect.

During this article, I’ll break down what a work breakdown structure is and give you a clear rundown of what you need to know about the WBS to support a successful project. You’ll learn:

What is the Work Breakdown Structure (WBS)?

The work breakdown structure (WBS) is a chart that outlines a project’s deliverables and components; it’s used to provide clarity on what the project needs to deliver.

The WBS is created as a hierarchy of things that the project will produce and organizes a team’s work into manageable chunks. The hierarchy is usually two to four levels deep. It clarifies exactly what’s going to be delivered at the end of the project and shows how those deliverables relate to one another.

Work Breakdown Structure screenshot

A conceptual illustration of a work breakdown structure.

A work breakdown structure as defined by the Sixth Edition of the PMBOK guide states:

“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 organizes and defines the total scope of the project and represents the work specified in the currently approved project scope statement”.

Many project managers realize that within a project, things can go wrong at any time for a magnitude of different reasons, but more often than not, a project will fail due to a poorly documented or non-existent WBS.

And the authors of Applying The Work Breakdown Structure To The Project Management Lifecycle confirm:

“A poorly constructed WBS can result in adverse project outcomes including ongoing, repeated project re-plans and extensions, unclear work assignments, scope creep or unmanageable, frequently changing scope, budget overrun, missed deadlines, and unusable new products or delivered features.

It’s worth noting that there are two ways of creating a WBS – either most commonly with deliverables as we described above, or alternatively with phases. The deliverables oriented WBS is most common, and is also known as Entity Oriented, Noun Oriented or a Product Oriented WBS.  The phase-oriented WBS is focussed instead on the tasks required to complete those deliverables. The other names for this that you might come across are – Activity or Task-Oriented, Verb Oriented, or Process Oriented WBS.

Important WBS definitions

Before we go into further detail, I wanted to explain a few terms that I will be using in this article.

  • Work Breakdown Structure: A deliverable-oriented collection of project components. Work that isn’t in the WBS isn’t in the project. The point of the WBS is to organize and define the project scope.
  • Progressive Elaboration: continuously improving and detailing a plan as more information becomes available. In layman’s terms: working with what you’ve got.
  • Critical Path: The sequence of stages that determines the minimum time needed for operation. Read more about this method in this article on project management methodologies.
  • 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)
  • Project Management Plan: Covers how the project will be implemented, examined, and controlled.

Why is a work breakdown structure important?

The WBS defines what the project is all about.

This detailed view of the project gives teams with the information they need to clarify the work required by each individual for all tasks. Without the WBS, it is likely that requirements will be missed, and further likely that the deliverables and maybe even the entire project will miss the mark.

The work breakdown structure document gives a clear overview of the outcomes of the project, the order in which activities need to be performed, and the required project deliverables. A WBS gives clarity to all team members about what outcomes need to happen and the work packages break down exactly what is included.

The level of detail in a WBS will depend on your project size, organization, and level of detail, but a good rule of thumb is to have a plan that is agile enough that you’re not spending your entire working week trying to keep it up to date!

Here are the key benefits of a work breakdown structure:

1. It increases clarity around roles and responsibilities.

Since the WBS breaks out and assigns all tasks to individuals, it clarifies who is responsible for which aspect of work and includes due dates for each deliverable. Team members gain a clear understanding of how their work contributes to meeting each deliverable and ultimately the overall project goals.

2. It helps ensure all tasks are completed properly and on time.

The WBS is the dissection of deliverables down to their smallest unit, making it more likely that no task is lost in the process. This breakdown process reduces ambiguity and confusion around what each team member is required to do, and when they need to have their work completed. Ultimately this also saves time, making better use of each individual’s workday and reducing waste.

3. It enables tracking of all activities.

As each task is identified, detailed, scheduled, and assigned to meet a specific goal, there is an identifiable baseline to which all work can be traced back. The ability to track activities increases the chances that the project can progress as expected to deliver the client the best product or service within scope.

The below image shows why the WBS is so important to detail the project deliverables and what are the required inputs.  tracking activities screenshotProject managers who do not include all of these inputs or try to skip this thorough step are more likely to run into problems further in their project.

Work Breakdown Structure VS Gantt Chart: What Should You Use?

The WBS breaks down what you are building for the project into smaller, more manageable components. The WBS shows what you are doing and the Gantt chart shows when you are doing it.

How you use a WBS

You use the WBS for scope control, including change management. The (WBS) is a hierarchical decomposition of a project into manageable chunks. It is graphical and shows all the project parts in an organized chart. Unlike a Gantt chart, it does not show the tasks organized in sequence over time.

How you use a Gantt chart

You use the Gantt chart for schedule control. A Gantt chart is created from the Work Breakdown Structure and tracks tasks across time. It shows the start and finish date of each task, their dependencies, and their relationship to each other in terms of sequencing.

WBS VS The Critical Path Method: Aren’t They The Same Thing?

A question that is often asked to me by Junior PMs is, “What’s the difference between the WBS and the Critical Path Method?” The critical path is the list of core project activities that need to be focused on to deliver the project within the triple constraint (time, budget, scope). If the critical path slips, then the project manager will have a consequence for the overall project in one or more of these three areas.

One difficult area of critical path project management is knowing how to estimate it and what float (if any) exists on the task duration.  To support this and also resource assignment there’s software that can be used and it’s important to ensure that as a project manager you are not only using the software correctly but you have the right software for your projects.

Work Breakdown Structure Best Practices

When creating a good WBS, you need to be aware of and understand the following.  These are important, key points that will steer you in the right direction:

1. Focus on deliverables

Ensure you’re breaking down the deliverables, not activities, required to produce those deliverables.

2. Make everything mutually exclusive

Ensure there is no overlap between components within the WBS.

3. Be consistent

The WBS serves as a framework for all subsequent planning activities so it needs to be clear and SMART with consistent levels of detail and breakdown on deliverables.

Those 3 things are general best practices. You need to have these at the top of your mind during the entire WBS process.

That said, here are some of my top tips for making a work breakdown structure once you get started.

6 Tips For Creating A Good WBS

1. Take time to understand your inputs and outputs.

Before entering your WBS in a program, make sure that you understand all of the inputs and what needs to be achieved.

I recommend starting with the project charter/scope documents and using this to highlight the key deliverables/objectives. I normally do this with sticky notes and plot out all of the high-level deliverables and then use different colors for the different layers within the task. I can then put this across a desk and gather input/agreement from my team. Working with sticky notes helps me think visually and share my inputs with the team.

If your team is working remotely, you can do this in various software. This is a great way to encourage the team to think about the sequence of activities and what’s involved.

2. Leverage your SMEs

Use subject matter experts to assist in the planning and sequence of tasks/ activities. This can help ensure that you’re keeping things in the right order.

3. Get feedback

Review your WBS with the PMO/resource manager to line up any key resourcing so that you can make sure that your plan is realistic and in alignment with your Resourcing plan.

4. Get buy-in

Buy-in is the key for any successful WBS, so make sure that you spend the time to go through it with your team to make sure that they’re aligned and agree

5. See the forest through the trees

Do not make the WBS too detailed as it will become too cumbersome to update. I normally suggest not breaking down any task if it takes less than a day to complete (for medium to large projects). Of course, if the task is extremely important or on the critical path then an exception can be made.

6. Follow a consistent process

Consider following a checklist like the one here to validate if your WBS is detailed enough

How To Create A WBS

To create a WBS you must first identify the main deliverables of your project. Once this is done, you start breaking down the deliverables into smaller chunks of work and creating branches. You continue breaking down your tasks until you reach a point where they are manageable. As a general rule of thumb, most people consider ‘manageable’, to be 80 hours work.

A WBS can be very unique and specific to every project manager. Each PM has its own way of breaking down deliverables and detailing what needs to happen. TechRepublic has a great article on the basics of a WBS which is worth a read before you get started.

  1. Using the advice above, create an overview of all of the high-level tasks and deliverables. Make sure that you include each deliverable so that the team can map out the necessary level of detail
  2. Once you’ve done this; work with your team to realign the tasks into a sequence for when the activity should be completed.
  3. Next, it’s time to work on effort estimation and scheduling.
  4. Finally, it’s time to look at resourcing and leveling to make sure that you have a realistic plan based on the resources that are available. This can be a tricky art to refine with your resource manager and I suggest making sure that you have the critical path clearly identified.
  5. Review the completed plan with your key team to ensure buy-in and alignment.

Work Breakdown Structure Example

I have included an example below of a WBS structure based on work packages and outputs which has helped me track deliverables and keep a clear focus on milestones and resourcing. What was most important for me in using a WBS was clarity and ability to filter on the key reportable aspects (i.e. the status of work packages/milestones).

breakdown structure screenshot

Work breakdown structure example showing the status of work packages and milestones.

Work Breakdown Structure Example: What Are The Different Parts?

Below, I break down what I put in each column of the work breakdown structure. I tell you where it’s located and how I use that part of the WBS.

Column Description/ Use
WP1 This is to give you a high-level view of all of the tasks related to a specific Work Package. I choose to work through the Work Package Numbers as it’s easier to keep track of when going into more detail. You can easily amend this to A, B, C, or another format if you’d prefer.
WP This is the subtask from the high-level Work Package (WP). When looking at the level of detail for each subtask, you can base it on the amount of effort (e.g. under 4hrs of work) being performed. Depending on the size of your WBS, I would recommend not creating any task that is less than 4hrs work.
Work package Number and Name This is a written description of the Work Package that it relates to. If you are not using Work Packages, you can use this field as “Description Title”.
Task A description of the task to be performed under this Work Package
Name The resource assigned to perform this task. Ideally, you should only have the responsible person listed here and avoid generic resources like departments or multiple names. You want to be able to make sure that you have someone accountable for each task.
Input/Output What is the input or output as a result of this activity? Is a document completed?
Effort How much effort does it take to complete? You calculate the effort associated with this task in collaboration with your team. It’s recommended to make sure that the person doing the task agrees and commits to the effort being put in the WBS. In the example here, we work in day increments.  For those tasks listed as Milestone; this is highlighted with a Red bar and a description of the Milestone number
Check This is a formula within Excel to ensure that the resources are not overallocated in your planning. It is a simple formula to check that the effort that you have entered, is correctly allocated across your WBS and that you do not have fewer or more hours assigned. This formula was created as a ‘second check’ for the Project Manager to make sure that the hours listed in the WBS were accurate and that resources were getting the right hours per week. I noticed that without this check, it took me a long time to verify that the effort was correct across the number of weeks that we were running.
Wk1/2/3 etc This is the calendar week broken down for your project. I have used weekly increments as the basis for this example as it’s the most common time frame used. If you’d like to use a different timeframe, please make sure that it’s not too cumbersome for you to maintain as shorter timeframes can add additional effort for you to complete.

Work Breakdown Structure Example: How To View All Resource Capacities?

Below, you will see an overview of the resourcing capacity that I calculate to the right of all of the WBS information covered above. It’s calculated based on the project requirements.

resource capacity overview screenshot

My tasks, names, inputs, outputs, efforts (etc) are on the left, and my resourcing capacity overview is included on the right, with a Check column and resourcing capacity listed by week.


requirements screenshot

“1” represents the number of days required to work by each resource during each of the weeks mentioned.

This can be really useful for discussing your requirements with the resource manager. What is really important for me is understanding the effort requirements over the duration of the project and making sure that the effort estimations from the team are realistic.

Conclusion

The WBS is one of the most important artifacts that a project manager needs to create during a project and will set the amateurs apart from the experienced project managers. What would your top tip be for creating a WBS? Do you agree with the steps here? Let’s start a dialogue and help other project managers share the knowledge!

 

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Emily Luijbregts

Emily Luijbregts

I’ve been working in Project Management for over 10 years. In this time, I have worked in a variety of Project Management methodologies and have been a strategic Project Manager, Facilitator and Scrum Master. I’m also an avid coach and trainer, who wants to ensure the development of the next generation of Project Managers and project professionals through training, knowledge sharing and team building. Within this I am always looking forward to lessons learned and what we can do better as Project Managers and colleagues.

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