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Articles 11 Feb 2022

What Is a Work Breakdown Structure (WBS)?

What Is a Work Breakdown Structure (WBS)?

A Work Breakdown Structure, or WBS, is very helpful in the project management field. It is a planning tool that clarifies the scope of work and helps project managers find project costs, develop a schedule, and monitor and control project work. It is also helpful to avoid any issues such as scope creep, cost overrun, and schedule delays

work breakdown structure in project management

Essentially, a WBS provides complete control over the project. That is the reason why today, project managers are more frequently using this method to ensure the project is successful.

Definition of Work Breakdown Structure (WBS)

A Work breakdown structure (WBS) is a project management method used on a complex, multi-step project to make its completion easier by dividing it and conquering each one separately. This method allows for tasks to get done faster and more efficiently. By breaking them down into smaller parts, time is utilised better because more work can be done simultaneously by different team members. That leads to better productivity and makes managing projects, team members and each separate task easier.

The Project Management Book of Knowledge (PMBOK) defines the WBS as a "deliverable oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and create the required deliverables."

wbs project management

The WBS is an important project management tool because it integrates scope, cost and schedule baselines, ensuring that project plans are in alignment. Unlike other tools, which focus on planned actions, this one focuses on planned outcomes. The WBS allows the project manager to oversee the completion of each task within a project.

Importance of Work Breakdown Structure in Project Management

Though it does have some disadvantages, the WBS has great importance in project management. It provides clarity in the scope of work so that project managers can identify all project activities with ease and see the dependencies amongst the project's tasks. This not only helps in avoiding complications like duplicated work and scope creep, but it is also helpful for determining task duration and calculating the budget for each work package.

Still, even with some disadvantages like difficulty in developing a WBS because of inexperience, time and effort needed or not having complete and detailed scope (or even having it, but letting WBS get out of control and not be updated properly) are overshadowed by its benefits. Using the Work Breakdown Structure has the following advantages:

Visuality

The Work Breakdown Structure is a visual tool. As such, it helps in creating an image of what the project entails, in a clear and vivid manner. Visualizing the individual steps and processes helps the users see the “big picture” of the project.

Complexity

Another great feature of the Work Breakdown Structure is its complexity. It consists of all the work steps, activities and tasks of the project and therefore is very detailed. This may seem confusing to first-time users, yet the complexity means all the nuances are taken into consideration.

Hierarchy

Another great feature of the Work Breakdown Structure is that it anticipates the hierarchy and portrays the high-level project as well as possible sub-projects, work packages, and individual tasks for team members.

Clarity

While the Work Breakdown Structure may end up being confusing, it offers a great deal of insight and shows often overlooked aspects of the given project. On the other hand, it reveals the area that might need to be cut or outsourced for better performance. Thus, visualisation through the Work Breakdown Structure helps gain clarity on the exact scope of the project.

These advantages of using WBS lead to benefits like increased responsibility and accountability and help you avoid duplication of tasks and scope creep as it clarifies the scope of work.

Types of WBS

types of wbs in project management

Although there are several different WBS types, most often the distinction is made according to whether the focus is on project deliverables or project schedule. The two most common WBS types are deliverable oriented WBS and phase-based WBS. But there are more than just these approaches, depending on the WBS elements and project managers preference.

Deliverable-Based Work Breakdown structure

If the WBS is primarily based on the deliverables of the project, then the structure is deliverable oriented. The main units will consist of the main groups of deliverables, such as individual services offered, and products delivered. This type of WBS is very useful to project manager who wants to see the total scope of a project and how each deliverable is related. By using this deliverable-based approach, managers can make more accurate resource and budget estimations because they can see all the project's levels.

Phase-Based Work Breakdown Structure

Unlike the deliverable-based approach which focuses on the end result of the project, this phase-based structure focuses on the individual project phases and organising all activities in a chronological way. The project phases typically include the planning, execution, control and closeout. This way of defining a WBS, like steps that need to be taken to accomplish a goal, has the benefit of creating a more coherent project scope.

Resource-Based Work Breakdown Structure

This structure is based on the type of resource or the business function of the resource. A resource can be a facility, a type of software used in the project, or equipment. Staffing is also part of the resource group.

Risk-Based Work Breakdown Structure

This type of structure is organised by the type of risk the project may encounter during its execution. The main groups of risks may include categories such as people, environment and equipment. Furthermore, the risks are colour-coded according to their impact. One popular risk management tool is the Risk Breakdown Structure

Responsibility-Based Work Breakdown Structure

The responsibility-based structure is based on the organisation units. Therefore, it organises all the activities by the teams or units that work on the project. Similarly, the structure can be based on the broader company organisation, including the project sponsor, the control board and stakeholders.

Whether it's deliverable-based, phase-based or any other structure type, the WBS is used as a starting point for scope management because it utilises the project charter as well as the project scope statement descriptions of the project outcomes.

Types of WBS Charts

After choosing what your WBS type will be, you can then continue on to choosing between different WBS diagram types. The WBS can be represented in a few different ways - either by the graphical, textual or tabular view. Seeing as the WBS conveys the total project scope to the relevant stakeholders, they must be presented well. The form of representation should be chosen according to the needs of the project.

These are the main chart types:

  • WBS List is probably the easiest method to use to create a WBS. It provides an outline view of tasks, deliverables and work packages;
  • WBS Tree Diagram is similar to the WBS list because it contains the same elements: phases, deliverables, tasks and work packages; but this type of WBSchart represents the progress via diagram;
  • WBS Spreadsheet is used to visually represent the order of tasks and project activities. It is also used as a schedule of resources as it shows what equipment, materials, time, cost and labour are needed during the completion of each task;
  • WBS Gantt chart is both a spreadsheet and a timeline. That way you can link dependencies, set milestones, even set a baseline. For that reason, the Gantt chart is one of the most used WBS chart types in project management. A Gantt chart is useful for planning and scheduling projects because it can help you assess how long a project should take, determine the resources needed, and plan the order in which the tasks should be completed. A Gantt chart is also useful for monitoring the progress along the way.

Depending on the project there can be many uses of these chart types. For example, the project manager will probably not use the same chart for a construction project as they would for people, or rather team, management.

How to create a work breakdown structure?

work breakdown structure (wbs)

Below are three steps that can be used as a guide in creating the Work Breakdown Structure. However, the process of creating a Work Breakdown Structure is comprehensively covered in our PMP Passport Course.

1. Define the scope of the project by determining deliverables and requirements

The very first step to creating a WBS is defining the scope itself. This is done by determining two aspects: deliverables and requirements.

Deliverables are characterised as all that the project team members produce and deliver during the project, be it the products or services. The deliverables are geared towards all the stakeholders. They may include project documents such as schedules, budgets, blueprints and other written documents. The role of these documents is to confirm the completion of a project or its phase and they contain results and outcomes that are clearly defined and measurable.

The scope is not defined through deliverables only. Another substantial aspect of the scope is the project requirements. Requirements, i.e. objectives to be met, are in fact descriptions of what the deliverables should look like from the point of view of functionality. They respond to questions of what, where, when, how much and who of the process. Requirements may possess specific and tangible characteristics such as colour, size, ingredients, etc. Besides being measurable, requirements should also be testable.

2. Decompose the deliverables into individual work packages

At the lowest level of the Work Breakdown Structure is a deliverable commonly referred to as the work package. They must communicate the entire scope of work contained in them in a way that leaves no ambiguity for the person executing the work. Determining these work packages of the individual deliverables is the basis for outlining the Work Breakdown Structure. This is done by:

  • Defining the work package
  • Determining its beginning and its end
  • Estimating its requirements and timeline
  • Integrating it within the other work packages on the given level of deliverables

3. Select the Work Breakdown Structure suitable for your project

While the Work Breakdown Structure is undoubtedly the cornerstone of scope planning, it is essential to select the right way of constructing it. This is the third and final step before you go on to actually design the Work Breakdown Structure of your project.

work breakdown structure advantages and disadvantages

4 Rules to consider while making Work Breakdown Structure

These rules are the key checkpoints for creating great Work Breakdown Structures. Their function is to help WBS support the project's execution strategy in the most effective way possible. Keep these five rules in mind to deliver a successful project.

1. The 100 % rule

This rule is the most important guideline to follow when creating the WBS. It is used not only for its construction but for the breakdown and evaluation of the WBS as well. The 100% rule states that the work breakdown structure includes 100% of work represented by the project scope. The project scope includes both internal and external deliverables, work packages and tasks that are then divided into the WBS levels. Hence why this rule is applicable to all levels of the project. And since no project can go beyond 100% of the work, this rule is also helpful for project managers to track what is not included in the actual project scope.

2. Levels

The levels of WBS are determining its hierarchy. Depending on the project, some branches of the WBS will be more subdivided than others, but for your project scope and WBS details to be right, there shouldn't be less than three levels in most branches.

3. The 8/80 rule

Properly created Work Breakdown Structures must be chunks of work that can be completed typically within 8 to 80 hours (this is a rule of thumb), depending on the size of the project.

Another criteria for work packages is that they must fit into the reporting period of the project. For example, smaller projects that have very large work packages and vice versa- large projects with very small work packages can create problems because of the misaligned size and reporting period. The misalignment will affect progress monitoring and it can create problems when reporting the progress to key stakeholders.

4. Outcomes, not actions

The focus of WBS is supposed to be on outcomes, not on the activities needed to reach them. Therefore, when creating the steps of WBS, project managers should consider "what" more than the "how". When making the WBS, use nouns instead of words to keep the focus on project deliverables themselves as opposed to activities attributing to the development of deliverables.

Work breakdown structure (WBS) example

importance of work breakdown structure

The Institute of Project Management is providing you with this work breakdown structure (WBS) example in order to demonstrate a work breakdown structure that could work for you in your own environment.