What Is A Work Breakdown Structure? Work Breakdown Structure In A Nutshell

A work breakdown structure is a simple and methodical means of organizing and understanding project scope. The approach enables businesses to take a top-down look at a project and break it into smaller tasks and subtasks that will assist in project completion. It also guides time and cost estimates and schedule development and control. A work breakdown structure (WBS) is a component of project management and systems engineering that breaks a project down into a hierarchy of tasks and deliverables.

DefinitionA Work Breakdown Structure (WBS) is a hierarchical decomposition of a project into smaller, manageable components or work packages. It is a visual representation that organizes the project’s tasks, deliverables, and activities in a structured manner. The WBS is a fundamental tool in project management for planning, organizing, and controlling project work.
Key ElementsHierarchy: The WBS is organized in a hierarchical structure, with the project at the top level and progressively detailed levels below.
Work Packages: Each level of the hierarchy represents a different level of detail, with work packages at the lowest level, which are the smallest units of work that can be assigned, estimated, and tracked.
Deliverables: The WBS represents both the project’s deliverables (end results) and the work required to produce them.
How It Works1. Define the Project Scope: Clearly define the scope of the project, including its objectives and deliverables.
2. Identify Major Phases: Break the project into major phases or milestones.
3. Create the WBS: Starting with the project’s main phases, progressively decompose each phase into smaller, more manageable components, using a hierarchical structure.
4. Assign Codes: Assign unique codes to each element of the WBS to facilitate organization and reference.
5. Review and Validate: Review the WBS with stakeholders to ensure completeness and alignment with project objectives.
6. Use for Planning: Utilize the WBS for project planning, resource allocation, scheduling, and budgeting.
7. Track Progress: As work progresses, use the WBS to track the completion of work packages and monitor project status.
BenefitsClarity: Provides a clear and structured view of the project’s scope and components.
Organizational Tool: Facilitates project organization, management, and communication.
Scope Control: Helps in controlling scope creep by clearly defining project boundaries.
Resource Allocation: Aids in resource allocation and assignment of responsibilities.
Estimation: Supports accurate time and cost estimation for each work package.
Risk Management: Helps identify potential risks and dependencies.
DrawbacksComplexity: Creating a detailed WBS for large projects can be time-consuming and complex.
Resource Intensive: Requires resources for the initial creation and ongoing management.
Scope Changes: May need revisions if project scope changes significantly.
Over-Emphasis on Detail: Can lead to an excessive focus on low-level tasks at the expense of high-level project goals.
ApplicationsProject Management: Used in various industries for project planning and execution.
Construction: Commonly employed in construction projects to break down tasks and phases.
Software Development: Applied to organize software development projects.
Engineering: Utilized in engineering projects to structure tasks and deliverables.
Event Planning: Useful for organizing and managing events and conferences.
Product Development: Helps in product development by breaking it into manageable steps.
ExamplesProject: Construction of a new office building.
Phase: Design phase of a software development project.
Deliverable: Creation of a marketing campaign for a new product launch.
Work Package: Writing a specific module of code for a software project.
Task: Procurement of materials for a construction project.
Subtask: Researching suppliers for construction materials.

Understanding a work breakdown structure

The work breakdown structure diagram illustrates the components of a project vital to its overall success.

The final project deliverable is placed at the top of the diagram, with multiple levels below that denoting the systems, sub-systems, components, tasks, subtasks, and work packages critical to project completion.

Work packages describe the work required to complete a specific job or process and occupy the lowest level of the WBS diagram.

The number of levels required depends on project complexity.

For moderately complex projects,  practitioners suggest using three or four levels.

More complex projects may require the full complement of six levels.

This process of breaking down the project into progressively smaller parts is called decomposition.

Developing a system for the construction of a new aircraft is one example of a complex project with many moving parts.

Using a work breakdown structure, the manufacturer may assign one system to aircraft construction and another to pilot training.

Within the system tasked with aircraft construction, there may be sub-elements for the airframe, navigation system, and landing gear.

Similarly, the airframe construction sub-system itself can be further divided into wings, tail, and fuselage components, and so on.

Creating a work breakdown structure

Following is a very general overview of the steps involved in creating a robust project estimate.

1 – List high-level deliverables 

The process starts with defining the project scope. What will the team need to deliver to meet the project end goal? 

For example, deliverables for a new company website may include blog content, page design, a sitemap, and front and back end code.

Discussing project deliverables as a team is vital because it allows expectations to be set around individual task responsibility.

2 – Segment each deliverable into tasks 

These tasks define how the deliverable will be met. In other words, what needs to be done to create the deliverable?

What are the task requirements? Are there other project tasks that will assist in its creation? Indeed, are there task interdependencies?

The elements in each level must be mutually exclusive.

To avoid duplication and reduce miscommunication, there must be no overlap in deliverables.

3 – Decompose with subtasks 

To make the work breakdown structure as detailed as possible, every task must be defined in terms of subtasks.

Every level of decomposition must comprise 100% of the level above it and incorporate at least two “child” subtasks. 

The process of meticulously ensuring that 100% of the scope is captured can be exhaustive, but investing in the approach now means a reduced likelihood of later budget blowouts and missed deadlines. 

The company developing a new website may test its navigation menu with ten users.

This task can be broken down into subtasks, including recruiting users, scheduling sessions, conducting sessions, compensating users for their time, and writing up findings and subsequent recommendations.

The decomposition process should continue until each element can be managed by a single individual or organization.

4 – Format the work breakdown structure and estimate the work 

Formatting is usually achieved through Gantt charts because they provide a convenient task hierarchy and are easily referenced.

However, a whiteboard or spreadsheet is just as effective. 

Once formatted, the team must discuss each task together and estimate a completion time. 

Summing the estimated completion time for each task will then let the team know whether the project is in or out of the scope defined at the outset.

Key takeaways

  • A work breakdown structure is a component of project management and systems engineering that breaks a project down into a hierarchy of tasks and deliverables
  • A work breakdown structure is particularly useful in complex projects requiring diligent and detailed planning. In a process called decomposition, the project is broken down into progressively smaller levels of deliverables and associated tasks.
  • The work breakdown structure process can be performed in four steps. The team starts by defining high-level deliverables and then segments them into tasks and sub-tasks. During the final step, the team assigns a time to completion estimate for each task and uses this information to determine whether the project can be delivered within scope.

Key Highlights

  • Project Scope Organization:
    • A Work Breakdown Structure (WBS) is a systematic approach to organize and understand the scope of a project.
  • Hierarchical Structure:
    • The WBS breaks down a project into a hierarchical structure with multiple levels, starting from the final project deliverable at the top and breaking down into systems, sub-systems, components, tasks, subtasks, and work packages.
  • Decomposition:
    • The process of breaking down the project into progressively smaller parts is called decomposition. It involves segmenting high-level deliverables into tasks, then further decomposing those tasks into subtasks.
  • Project Complexity and Levels:
    • The number of levels in the WBS depends on project complexity. Moderately complex projects may use three or four levels, while more complex projects might use up to six levels.
  • Detailed Planning:
    • The WBS is particularly useful for complex projects that require detailed planning and management. It helps ensure that all aspects of the project are considered and accounted for.
  • Segmenting Deliverables:
    • The process starts by listing high-level deliverables that the project team needs to achieve. For example, a new company website project might include deliverables like blog content, design, and coding.
  • Task Definition and Subtasks:
    • Each deliverable is then segmented into tasks, defining how each deliverable will be achieved. Tasks can be broken down further into subtasks for greater detail.
  • Mutually Exclusive Elements:
    • To prevent overlap and miscommunication, each level of deliverables and tasks should be mutually exclusive.
  • Decomposing Subtasks:
    • To enhance detail, tasks are decomposed into subtasks. Each level of decomposition should cover 100% of the level above and include at least two “child” subtasks.
  • Format and Estimation:
    • The WBS can be formatted using tools like Gantt charts, spreadsheets, or whiteboards. The team estimates completion times for each task, and the sum of these estimates determines if the project is within scope.
  • Effective Project Management:
    • WBS helps in effective project management by providing a structured approach to planning, organizing, and tracking tasks and deliverables.

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