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Using the Resource Breakdown Structure (RBS) 

 May 14, 2024

By  Dave Litten

Using the Resource Breakdown Structure (RBS)

A Resource Breakdown Structure (RBS) is a hierarchical breakdown of resources required by a project by their categories and types used in project management to organize and plan project resources for a project. It also helps track resource-related costs.

An RBS covers all monetary items such as people, project management tools, equipment, materials, and even fees and licenses. In doing so, it helps create the project budget.

The resource breakdown structure helps project managers better organize resources, estimate costs, and align resources with project objectives.

The RBS is used to facilitate the planning and controlling of project work. It is related to the work breakdown structure (WBS), which lays out the tasks and deliverables of a project

The resource breakdown structure is a tree diagram, with the top element as the final project deliverable.  Beneath this are the resource types such as people, time, materials, equipment, facilities, and finances. 

The resource breakdown structure helps the project manager create a resource plan.

A spreadsheet can also be used to create a horizontal breakdown of resources. It will start with the resource number on the left and move across the spreadsheet to detail the resource categories and types, quantity, and notes.

Here is a generic example:

The Resource Breakdown Structure

In terms of format, the resource breakdown structure is like the work breakdown structure and requires an estimation of which resources will be needed for each task in the project. Therefore, the task list is essential for collecting the necessary resources.

The project manager is responsible for using the resource breakdown structure, though they will usually seek input from others on the team. It allows them to identify how many resources they need, breaking the project down to the task level and the resources needed for each one. 

Resource Breakdown Structure (RBS)

The project manager will gather input from the project schedule, risk register, and cost estimates to capture the full project scope.

A resource breakdown structure helps better organize resources by aligning with the organization’s goals and objectives, providing a quick visual reference on resource allocation and workload, as well as individual resources and assignments.

By thoroughly listing project resources, the resource breakdown structure assists in estimating project costs and aligns resources with the overall goals and objectives of the organization.

The project manager is responsible for using the resource breakdown structure is created during the planning stage of a project, but may seek input from other team members.

The Resource Breakdown Structure is closely related to the Work Breakdown Structure

Work breakdown structure

This is a hierarchy of all work to be done during a project that forming a link between the product breakdown structure and the work packages.

The work breakdown structure is most useful when there are multiple work packages and specifically when there is a mix of internally staffed and externally supplied work packages. 

For the former, it makes clear the level of effort of internal staff, and for the latter, it is useful in creating a statement of the work required. 

A Work Breakdown Structure would not be required for a very simple project, such as the delivery of just one work package with a small team.

If a single work package is being used in the project, it shouldn’t include both internal and external team members. 

There is a fundamentally different character and set of relationships between an internal agreement and an external contract. Therefore, it is better to manage them separately.

The project organizational design is informed by the work breakdown structure and the commercial management approach. 

These will determine the number and size of teams, which organizations they come from, and the nature of any customer or supplier relationships required. 

The capabilities required of a project delivered by people entirely from within the business will be quite different from those required of a project mostly delivered by external suppliers.

The purpose of the project plan is to provide confidence to the project board that the project will fulfil its business case. The project plan also informs the project management team that they have a viable approach to deliver the required products within the approved resources and tolerances.

The project plan should identify the number of stages and details of the stage boundaries, as well as proposed work packages into which the product delivery activities will be organized. 

These work packages typically represent the top level of the project’s work breakdown structure. 

The project plan should state whether each work package will be delivered sequentially or in an iterative-incremental manner.

In an iterative-incremental project, some work packages may be detailed in a subsequent stage plan, but their general purpose and scope should be stated in the project plan.

A work breakdown structure for the stage, identifying the major activities to be performed during the stage and the people and resources involved in each of these activities, should also be included in each stage plan.

When planning a project, the work breakdown structure is used to support project organization by mapping work packages to the teams or suppliers responsible for delivering the associated products. 

This application is particularly helpful when a project has a mix of work packages, with one or more being delivered through internal staff and others by external suppliers. 

Where people represent a major element of the project’s costs, the work breakdown structure allows labour costs to be described in terms of types of skills, level of effort, and duration of effort.

The work breakdown structure helps develop team plans, where necessary work to deliver the products can be detailed regarding tasks and the team members assigned to them. 

The work breakdown structure is optional for simple projects with one or two products or work packages and small delivery teams.

The product breakdown structure, product flow diagram, and work breakdown structure may be maintained in a document, spreadsheet, or graphical planning tool. 

Multiple elements may be maintained in a team collaboration tool. Even so, it is often useful to prepare a narrative document that explains the plan

Dave Litten


Dave spent 25+ years as a senior project manager for UK and USA multinationals and has deep experience in project management. He now develops a wide range of Project Management Masterclasses, under the Projex Academy brand name. In addition, David runs project management training seminars across the world, and is a prolific writer on the many topics of project management.

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