What is a work breakdown structure and how does it apply to a project schedule?

A Work Breakdown Structure (WBS) is a hierarchical outline of the tasks required to complete a project. The WBS “breaks down” the structure of a project into manageable deliverables.

A Work Breakdown Structure (WBS) is a hierarchical outline of the tasks required to complete a project. The WBS “breaks down” the structure of a project into manageable deliverables. Each deliverable is assigned a task, or series of tasks that can be further broken down into subtasks to meet the needs of the project.

The advantage of using a WBS as part of project lifecycle management is that is takes large, complex projects and breaks them into smaller, more manageable tasks that can be assigned to specific people or teams to deliver.

Purpose of the Work Breakdown Structure

The primary purpose of the WBS is too plan the schedule for the project. Each task duration is planned in conjunction with its required predecessors and following tasks. The WBS then provides an overall plan so that the project manager can see how the project should progress and manage the workflow appropriately.

Related: What is a Cost Breakdown Structure?

WBS Components

The parts of the WBS include:

• Tasks – a number, ID, title, and description of each task.
• Task Owner – who is responsible for completing the task.
• Task Dependency and Predecessors – linking two tasks together if one depends on the completion of the other.
• Start and Finish Date of Task – estimates the time each task will take and ultimately the entire project.
• Duration – how long will each task take on the calendar (usually number of days or hours).
• Work Estimate – how many hours/days of work are required to complete the task (combining all resource hours together if working in parallel).
• Task Status – whether each task is assigned to an owner/resource, started, in progress, late, complete, etc.
• Gantt Chart – a visualization of the WBS with tasks represented graphically over time.

Work Breakdown Structure Example

The WBS is a central component of Project Business Automation, as it acts as the primary schedule against which all other activities and system operations are executed.

See How the Work Breakdown Structure in PBA Works

Eliminate standalone project management applications and the overhead needed to manage them.

• Leverage the project schedule to accurately build a labor budget, time-phase earned value estimates, and generate cash flow projections
• Apply the timeline directly to MRP for production orders, and automatically constrain the schedule based on procurement or production delays
• Staff projects more efficiently and automatically feed status updates, issues and work estimates back to the schedule from the timesheet
• Evaluate cost to complete with real-time work estimates from the schedule
• Report on the financial impact of schedule changes immediately

To learn how a WBS should be integrated into the rest of your project processes and systems, Download the Project Business Automation Blueprint. It is the definitive guide to creating a comprehensive business system for your Project Business that ties together your project operations and financials seamlessly.

The Difference Between WBS and CBS

The WBS is an operational plan – what work will be done, how it will be completed and on what schedule. The Cost Breakdown Structure (CBS) is the financial plan of the project. Many companies use the WBS as their financial plan as well. However, this approach often leads to financial problems with the project. The WBS is far to granular to be able to manage costs effectively. Or, it can be far to general to get the right cost details and apply them to the appropriate general ledger areas.

The CBS is the answer. The CBS is linked to the WBS, but allows for a complete breakdown of the project for financial purposes, which enables effective project cost control and earned value analysis.

The project schedule is the tool that communicates what work needs to be performed, which resources of the organization will perform the work and the timeframes in which that work needs to be performed. The project schedule should reflect all of the work associated with delivering the project on time. Without a full and complete schedule, the project manager will be unable to communicate the complete effort, in terms of cost and resources, necessary to deliver the project.

Online project management software allows project managers to track project schedules, resources, budgets and project related assets in real time. The project schedule can be viewed and updated by team members associated with the project, keeping everyone well informed on the overall project status.

Work Breakdown Structure (WBS)

The building blocks of a schedule start with a Work Breakdown Structure (WBS). The WBS is a hierarchical reflection of all the work in the project in terms of deliverables. In order to produce these deliverables, work must be performed.

A typical approach in developing a WBS is to start at the highest level, with the product of the project. For example, you are assigned as the project manager of a New Product Development project. The new product you are developing is a new toy for children age's five through nine. The objective of this product development project is to increase the revenue of the organization by ten percent.

Example of WBS:

Above is an example of a WBS for this new toy. Each level of the WBS is a level of detail created by decomposition. Decomposition is the process of breaking down the work into smaller, more manageable components. The elements at the lowest level of the WBS are called tasks. In the example above, brochures, advertising and commercials are all work packages or tasks.

Marketing collateral is on a summary level called a control account in project management parlance. In Project Insight, project management software, control accounts are called 'summary tasks.' Summary tasks are roll ups of the tasks underneath them.

The decomposition of a schedule will continue at varying rates. 'Brochures' is a task identified at the fourth level of decomposition, while the 'marketing plan' is also a task, but defined at the third level of decomposition.

As a project manager, the level of decomposition will be dependent on the extent to which you will need to manage. Project Insight supports as many levels of hierarchy as are needed. The expectation is that each task will have a single owner and the owner is expected to manage and report on the work necessary to deliver the task. In Project Insight, this is called the 'task owner.' If you cannot assign a single owner, or you need to have additional visibility into the progress of that task, additional decomposition is recommended.

Once all the deliverables of the project have been identified, tasks will be performed in order to create the deliverables. In some cases, these activities are the physical deliverables, but in other cases they are the actions that need to be performed. A physical deliverable, for example, might be an image (an actual file) that is needed for the brochure. Listing out each of the tasks to be performed will result in an activity list as demonstrated below.

Product Development Activity List

The work package 'focus group' actually consists of three (3) separate tasks—'identify focus group targets,' 'prepare focus group objectives' and 'perform focus group.' The work package 'surveys,' on the other hand, is not broken down into tasks. In our example, it may have been determined that the task owner that is performing the surveys does not need to report on any of the details of that task. As stated earlier, decomposition will continue to the level that is necessary to effectively manage the project.

What is a WBS work breakdown structure and how is it used to schedule a project?

What is the WBS and why is it important for the project schedule?

How does the work breakdown structure WBS fit into project time management?

Is a work breakdown structure is created from a project schedule?