Work Breakdown Structure in Project Management: Explained

A Work Breakdown Structure (WBS) is one of the most fundamental project management tools. It dates as far back as the 1960s and is used by the United States DoD and small projects alike. However, today the popular chart has evolved into different forms – some even going into a little too much detail. 

A Work Breakdown Structure was originally intended to give you a complete layout of the project’s deliverables. It isn’t going to do the job of a Project Schedule, a Gantt Chart, or for PERT. BUT, it does create the foundation for all of them! 

In this blog, we’ll show you the benefits of a Work Breakdown Structure in project management, and how to create a good one! 

What is a Work Breakdown Structure (WBS)?

Work Breakdown Structure (WBS) is a chart that shows the total scope of the project in terms of deliverables. 

It is a hierarchical representation of the work that is to be done to meet the project’s objectives. 

Note: While talking about the WBS, “work” refers to work products or deliverables that are the “product of activity” and not the activity itself.

 The top components give a broad overview of the deliverables. And, as you go lower in the levels of the WBS, the deliverables become smaller and more manageable. All of the components add up to give a 100% overview of the project. 

Small highlight on Project Scope Statement vs WBS:

A project scope statement is created and approved first. It mentions the scope of the project, the major deliverables, and the assumptions and constraints you have. A Work Breakdown Structure builds on the scope statement and organizes it hierarchically for a better visual view of the project. 

Types Of Work Breakdown Structure

For this blog, we’ll mainly be focusing on Work breakdown structures for predictive or waterfall projects. So, in predictive projects, the WBS charts are usually structured based on the deliverables or phases of your project. Let’s see the difference between the two:

Deliverable-Based WBS

In this type of WBS, the top level represents high-level deliverables, with lower levels breaking them down into more detailed components.

For example, in a construction project, the top-level deliverables might include:

• Foundation (further broken down into excavation, concrete pouring, reinforcement, etc.)
• Structure (walls, framing, roofing)
• Interiors (plumbing, electrical, flooring, painting)

Phase-Based WBS

Since predictive projects have clearly defined sequential phases, the “phases” can become top-level components for the WBS. Here the WBS aligns with the predictive project life cycle. 

For instance, in software development, the WBS levels may follow phases such as:

• Initiation (requirements gathering, feasibility study)
• Planning (resource allocation, scheduling)
• Execution (coding, integration)
• Testing (unit testing, system testing)
• Deployment & Maintenance (release, updates, support)

Both deliverable-based and phase-based WBS structures help in organizing the project scope. You can choose a type based on your project’s requirements, company’s standards, or project structure. 

Purpose of a Work Breakdown Structure

Projects come with a high degree of uncertainty. It can fall into chaos easily if the initial planning isn’t strong enough. Here, a work breakdown structure helps by breaking down the main project goal into smaller parts. 

A WBS is necessary for all types of projects – regardless of the project life cycle, industry, niche, type of deliverables, and even project management methodologies. Here’s the main purpose of a WBS:

• To give a visual representation of the project scope and structure.
• To set a framework for project planning, controlling, execution, and management.
• To connect project objectives with measurable outputs.
• To divide the work into work packages that the team is familiar with. 
• To clearly define what is in/not in scope to prevent scope creep.
• To form a basis for scope, risk, budget, resource, and performance tracking. 
• To avoid duplication of work & reduce inefficiencies and errors.
• To show different levels of detail for different management levels (high-level summaries for executives and detailed breakdowns for teams).
• To report project progress in a standard format.
• To display all available project information.

Benefits of Using a Work Breakdown Structure 

While the purpose cleared why a work breakdown structure is necessary for a project, let’s look at some added benefits of using a WBS. 

• Creates a Common Language for Stakeholders – A WBS gives all stakeholders a clear and 100% vision of the project and hence makes communication easier. It ensures everyone is working from the same structure and that there’s no misalignment in the project team.
• Minimizes uncertainty – A WBS helps you delineate the project plan, which cuts down the uncertainty. It divides the “completely uncertain” project as a whole into work packages with way less uncertainties – since the team may have already worked with it before. 
• Lowers Risks – A WBS ensures a clear understanding of scope and expectations across the team. This helps you properly manage cost, budget, schedule, resources, quality, and technical aspects of the work – which in turn lowers the associated risks. 
• Eases Responsibility Assignment – Without a precise structure for work to be done, ownership delegation becomes difficult. A well-made WBS helps map out accountability easily. It also helps you further create a RACI matrix to assign responsibilities for each work package. 
• Prevents Scope Creep – Since the work is completely mapped out in a WBS, there is a clear boundary set for all stakeholders. This prevents scope expansion and associated project delays. 
• Improves Cost Estimation & Resource Allocation – A WBS helps you track the project goals and deliverables at every stage. So, it helps you estimate costs and predict resource requirements more accurately. Thus, it helps prevent cost overruns, and over/under-utilization of resources.
• Improves Planning and Scheduling – A good WBS helps in creating a realistic project schedule as well as estimating deadlines. It also forms the basis for creating a Gantt chart or using the Critical Path Method later in the project timeline. 

Key Parts of A Work Breakdown Structure (WBS)

1. WBS Levels:

A Work Breakdown Structure is divided into levels, where higher levels indicate broader goals/deliverables and lower ones are more detailed, smaller subdivisions. Usually, 3 WBS levels are enough to give an appropriate overview of the project. 

2. Deliverables:

Deliverables are unique and verifiable products or results on a WBS. These are components that need to be produced at each stage of a phase/process, to result in final project completion. These are the mid-level components of a WBS.

3. Work packages:

The goal of the WBS is to divide the entire project scope into manageable, measurable, and controllable “work packages”. These work packages are the smallest components of a WBS and cannot be broken down further. These are placed at the lowest level of a WBS hierarchy.

4. Control Accounts:

Control Accounts are WBS elements at which you plan to monitor and report performance. It is a checkpoint for management where scope, budget, actual cost, and schedule are reported for EVM (Earned Value Management) and performance reporting. It can be any element in the WBS. 

5. Planning packages:

It defines future work within the scope of the project. While creating the WBS, it has known work content but doesn’t have a known set of activities and schedule. (For example: Fixtures in a project that might occur later. You can’t have the fixtures identified beforehand). Planning packages are placed under a control account and are updated to work packages once the details are identified. 

6. Coding scheme:

The elements of a WBS are marked with a “WBS code”. The coding scheme indicates the WBS levels. For example, for a phased-based WBS, Initiation, Planning, and Execution will have WBS codes: 1,2, and 3 respectively. The subsequent elements will be numbered as 1.1, 2.1, 2.2, … (for 2nd level elements) and 1.1.1, 2.1.2, 2.2.4, and so on for lower level elements. 

 7. WBS Dictionary:

The WBS dictionary is a document that supports the WBS chart. It gives more details about the activities, dependencies, estimates, constraints, etc for the project. It is generally formatted as a table with the WBS codes, Level, Component name listed in each row. 

The WBS Dictionary can include the following:

• Descriptions
• Assumptions & Constraints
• Milestones
• Schedule
• Responsible teams or members
• Quality Requirements
• Cost estimates

The purpose of the WBS dictionary is to remove any room for ambiguity in the project and clarify the work for the team and team members. It is usually revised several times so that the WBS is accurately explained through the WBS dictionary. Sample WBS dictionary:

How to Create a Work Breakdown Structure

As per the Practice Standard for Work Breakdown Structure 3rd Edition by PMI, Level 1 of a WBS forms the project title, Level 2 contains the phases or major deliverables, and Level 3 the work packages. Let’s see how to draw a Work Breakdown Structure (WBS) with an example.

Here, we’ll take an example of a Car Manufacturing Project. The WBS can be displayed horizontally in an outline format or vertically as a tree structure (like an organizational chart). We’ll show you how to create both. 

Step 1: Define the Project Title (Level 1)

The highest level of the WBS represents the entire project scope. This is the final output that the project aims to deliver.

For this Work Breakdown Structure Example for Project Management, the scope is to create a fully assembled car, ready for testing. This becomes your Level 1 project title:

1.0 Car Manufacturing Project

Assign WBS code 1.0 to this project title. Each project will have a unique WBS code to avoid confusion and to identify and track work across multiple projects.

Step 2: Identify Major Deliverables (Level 2)

Now, let’s break down the main outputs of the car manufacturing project into Level 2 deliverables:

1.0 Car Manufacturing Project 

• 1.1 Chassis & Body

• 1.2 Powertrain

• 1.3 Electrical & Electronics

• 1.4 Interior & Comfort

These are very broad deliverables that we identified, which contribute to the completion of the fully assembled car. Let’s break these down to level 3 – our final level, with work packages. 

Step 3: Define Work Packages (Level 3)

Our Level 3 components would be the smallest components of this WBS. These are deliverables that are easy and efficient to plan, manage, and track the project’s progress.

1.0 Car Manufacturing Project 

1.1 Chassis & Body

• 1.1.1 Chassis Frame

• 1.1.2 Body Panels

• 1.1.3 Painting & Coating

1.2 Powertrain

• 1.2.1 Engine Assembly

• 1.2.2 Transmission System

• 1.2.3 Exhaust System

1.3 Electrical & Electronics

• 1.3.1 Wiring & Harnesses

• 1.3.2 Battery & Charging System

• 1.3.3 Infotainment & Dashboard

1.4 Interior & Comfort

• 1.4.1 Seats & Upholstery

• 1.4.2 Air Conditioning & HVAC

• 1.4.3 Interior Trim & Panels

Step 4: Assign Control Accounts

Note that you can assign control accounts here if you need to specifically look into and control a part of the WBS. 

For example, here, Powertrain components (engine, transmission, exhaust) are critical to vehicle performance and safety. It is a crucial point to look out for risks or failure. So, we can assign a control account like so: 

1.2 Powertrain (Control Account – High Risk)

• 1.2.1 Engine Assembly

• 1.2.2 Transmission System

• 1.2.3 Exhaust System

Step 5: Create the WBS Dictionary

Now, from the work packages, you can create the WBS dictionary that contains all the extra details about each component. You can use the format that we showed in the previous section of this blog for this. 

Rules To Create a Work Breakdown Structure

• 100% Rule: All components must constitute 100% of the work required to meet the project scope.  
• 8/80 Rule: A work package should take between 8 to 80 hours of effort. Avoid excessive decomposition. 
• Duplication: Do not account for any work twice.
• Outcomes, not action: Use nouns to define deliverables, not verbs.
• Do not include costs, time, resources, or dependencies. (You can add them in the WBS Dictionary).
• Do not imply task sequence or scheduling.

Tools to Create a Work Breakdown Structure

You can use several tools to create a work breakdown structure – the simplest being pen and paper or your conference room whiteboard. You can also use:

• Excel: The simplest yet the most effective way to create a work breakdown structure is through plain old Excel. You can outline the hierarchy based on WBS codes, or create a tree diagram using SmartArt. Select the Hierarchy diagram on SmartArt, add the deliverables in the text panel, customize the style, and you’re good to go!
• Word: While Word is not the most intuitive software for a WBS chart, you can use SmartArt on it too. You can also manually drag and drop shapes to draw a WBS on Word or use existing WBS templates online. 
• Microsoft Project: You can use its dedicated WBS feature for it. It even automatically assigns WBS codes based on task hierarchy. Alternatively, you can use Summary Tasks for a WBS. Simply add top-level components as summary tasks, and the subsequent levels as subordinate tasks.
• Canva – Whiteboard: Canva’s whiteboard feature allows you to design a WBS visually with drag-and-drop elements. You can use existing templates or create your own using shapes and elements.
• Miro: You can use sticky notes, mind-mapping features, and ready-made templates to break down tasks on Miro. The sticky notes give more freedom for brainstorming and adding ideas to the board. 
• Trello: Trello has a Breakdown structure powerup you can use to create complex work breakdown structures. For simpler projects, you can create lists on a Trello Board, add cards to them, and add descriptions, checklists, and so on for an easy WBS. 
• Asana: Asana supports hierarchical task breakdown so you can create parent tasks, subtasks, and dependencies. It also allows you to assign team members and set deadlines so you can track progress easily. 

FAQs:

1. What Do You Mean By Work Breakdown Structure?

A work breakdown structure (WBS) is a hierarchical division of a project into smaller deliverables. It compiles all the required work to meet the project goals and gives a shared roadmap for execution. 

2. Concept Difference: Cost Breakdown Structure vs Work Breakdown Structure

A Cost Breakdown Structure (CBS) groups project costs based on budget categories, while a Work Breakdown Structure (WBS) divides project scope into deliverables and work packages. CBS tracks expenses, whereas WBS organizes work.

3. Advantages And Disadvantages Of Work Breakdown Structure In Project Management

Advantages of WBS:

• Provides clear structure for project planning.
• Reduces uncertainty in the project
• Aids in cost and resource estimation.
• Helps in risk identification by isolating potential problem areas.

Disadvantages of WBS:

• Does not show task dependencies or workflows— needs integration with other tools.
• Requires frequent updates as more details are found.
• Risk of over-decomposition, if not created properly.
• Conventional Work Breakdown Structure can have issues like rigidity, and lack of adaptability. 

4. What is a Work Breakdown Structure Gantt Chart

A WBS Gantt Chart combines a Work Breakdown Structure with a project timeline. It visually maps WBS elements against a schedule, showing when each work package is planned to start and finish. This helps in tracking progress and aligning tasks with deadlines.

5. Explain Different WBS Formats: Table, List, Tree Diagram

• Table Format: Displays WBS elements in a structured grid with columns showing different levels, and rows the components.
• List Format: Represents WBS in a simple numbered, hierarchical list that is easy to read and reference.
• Tree Diagram Format: A visual representation of the WBS levels, providing a clear breakdown graphically.