Step 3: Define the Work Breakdown Structure (WBS)

Step 3: Define the Work Breakdown Structure (WBS)

The WBS should be established before adding activities and logic to the schedule. This ensures a clear definition of scope from the outset and prevents costly restructuring later.

The WBS is a visual project breakdown that organises deliverables into different levels based on dependencies. It is essentially a project plan in visual form — with the project objective at the top and sub-dependencies below. Project managers use the WBS to break down complex scopes, visualise dependencies, and provide team members with a project overview.

Types of WBS

There are two primary types:

• Deliverable-based WBS — supports the project scope; organises work by what must be produced.
• Phase-based WBS — organises work based on project phases and the overall timeline.

What the WBS Must Capture

The WBS should accurately capture all time-phased deliverables and components of a project. Key considerations when setting up a project's WBS include:

• Project reporting requirements.
• Project phases and stages.
• Project areas and zones.
• Contracts, subcontracts, and packages of work.
• Disciplines of work (e.g. civil works).
• Cost control and Earned Value Management (if required).
• Structured to provide flexibility to accommodate new and additional scope or requirements.

WBS & CBS Alignment

If there is a project requirement to align the program with financial and cost tracking tools (e.g. Earned Value, cash flow), there must be enough flexibility in the program's WBS or Activity Codes to align with coding systems used elsewhere — such as the Cost Breakdown Structure (CBS).

• This typically requires workshops and meetings with Planning, Cost, and Design teams to ensure the differing needs of each department are met.
• WBS and CBS alignment is often only practical at the higher levels of the WBS, and must be done in the initial stages of the project — before the schedule, cost estimate, and scope have been developed in detail.
• Recasting or revising a WBS part way through delivery can be very difficult and is often not feasible.
• Lower-level alignment between WBS and CBS is best achieved using CPM software Activity Codes to map discrete systems and deliverables within the CBS to the schedule.

Example: Deliverable-Based WBS — Simple House Construction

Example: Phase-Based WBS — Construction Project