Resource Breakdown Structure: Hierarchical Resource Planning for Exam Success

PMBOK v8 Definition

A resource breakdown structure is a hierarchical representation of resources by category and type. The resource breakdown structure is used for planning, managing, and controlling project work. Each descending (lower) level represents an increasingly detailed description of the resource until the information is small enough to be used in conjunction with the WBS to allow the work to be planned, monitored, and controlled. Examples of resource categories include but are not limited to labor, materials, equipment, and supplies. Resource types may include the skill level, grade level, required certifications, or other information as appropriate to the project.

Why It Matters for the Exam

The resource breakdown structure (RBS) frequently appears in PMI exam questions about resource management planning and scope-resource integration. You will encounter it in situational questions where the project manager needs to categorize resources for better control, as well as in definition-based questions that test your ability to distinguish the RBS from other hierarchical structures like the WBS and OBS.

Key Points to Remember (for the exam)

• Definition: A hierarchical representation of resources by category (labor, materials, equipment, supplies) and type (skill level, grade level, certifications)
• Primary Purpose: Used for planning, managing, and controlling project work
• Key Integration: Used in conjunction with the WBS to allow work to be planned, monitored, and controlled
• Hierarchy Logic: Each descending (lower) level represents an increasingly detailed description of the resource
• Common Confusion: The RBS categorizes resources (who/what performs work), NOT the work itself (that is the WBS) or the organization structure (that is the OBS)
• Exam Tip: When a question mentions grouping resources by "skill level" or "grade level," the answer is the resource breakdown structure
• Distinct from: Value breakdown structure (VBS), which is a WBS with value estimates assigned to each element

Typical PMI Exam Example

A project manager is planning a large construction project. The team needs to organize all resources—including carpenters (labor with specific skill levels), concrete (materials), cranes (equipment), and safety gear (supplies)—into categories for effective planning and control. Which document should the project manager create?

Answer: Resource breakdown structure (RBS)

PMI Exam Traps

• Trap: Confusing the RBS with the WBS

  • Reality: The WBS decomposes scope of work (deliverables); the RBS decomposes resources (categories and types)

• Trap: Thinking the RBS only includes labor

  • Reality: The RBS includes four categories: labor, materials, equipment, and supplies

• Trap: Assuming the RBS is only for large projects

  • Reality: The RBS is used for planning, managing, and controlling project work on any project where resource categorization adds value

• Trap: Confusing the RBS with the OBS

  • Reality: The OBS shows the relationship between project activities and organizational units; the RBS shows resource categories and types

Important PMI Connections

Quick Review Questions

1. A project manager needs to organize project resources by category (labor, materials, equipment, supplies) and by type (skill level, certifications). Which document should be created?

2. In the resource breakdown structure, what does each descending (lower) level represent?

3. True or False: The resource breakdown structure is used independently of the WBS for planning project work.

4. Which hierarchical structure shows the relationship between project activities and the organizational units that will perform those activities?

5. A project includes resources with different grade levels and required certifications. Which structure captures this information?

PMBOK v8 Reference

Section 4.2 - Develop Project Management Plan (Resource Breakdown Structure as a planning artifact) and Section 9.1 - Plan Resource Management (Resource Breakdown Structure as a key output/tool)