---
title: "Work breakdown structure (WBS)"
subject: "ICT Project Management"
chapter: 7
key: "semester_7/ict_project_management:work-breakdown-structure"
source: https://www.bctengineer.com/q/semester_7/ict_project_management/work-breakdown-structure
site: BCT Engineering
---

# Work breakdown structure (WBS)

ICT Project Management · Chapter 7: Project Integration Management

- Asked in: year not given; year not given
- Video: [Project Management: What is a Work Breakdown Structure?](https://www.youtube.com/watch?v=wEWhnodF6ig) — ProjectManager
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/ict_project_management/work-breakdown-structure
- Whole chapter: https://www.bctengineer.com/md/semester_7/ict_project_management/chapter-7

## Question

What do you mean by work breakdown structure (WBS)?

## Short answer

A deliverable-oriented hierarchical decomposition of total project scope, where each lower level provides more detail. The lowest level is a work package. It follows the 100% rule, forms the scope baseline, and is the basis for estimating, scheduling, and assigning responsibility.

## Answer

A **Work Breakdown Structure (WBS)** is a deliverable-oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and create the required deliverables. Each lower level gives a more detailed definition of the work. The lowest level is a **work package**. The WBS organises and defines the total scope; work not in the WBS is outside the project.

#### Features
- Deliverable-oriented, not activity-oriented, using nouns.
- Follows the **100% rule**: the WBS includes all work, and children add to 100% of the parent.
- Forms the **scope baseline** with the scope statement and WBS dictionary.
- Basis for estimating cost and time, assigning responsibility, scheduling and risk identification.

#### Example (website project)
```text
Website project
|-- 1 Management
|     1.1 Plan   1.2 Reports
|-- 2 Design
|     2.1 UI mockups   2.2 Database
|-- 3 Development
|     3.1 Front end   3.2 Back end
|-- 4 Testing
|-- 5 Deployment and training
```

#### Approaches to build a WBS
1. Using guidelines and templates.
2. Analogy (reuse similar WBS).
3. Top-down (start from major deliverables).
4. Bottom-up (list all tasks, then group).
5. Mind mapping.

#### WBS dictionary
A document describing each element: description, responsible person, schedule milestones, cost, quality requirement, acceptance criteria.

#### Benefits
- Prevents work being forgotten.
- Gives clear picture of scope to all stakeholders.
- Allows accurate estimates of small work packages.
- Helps with responsibility assignment (RAM) and risk identification.
- Provides progress tracking basis.

#### Forms
Hierarchical chart (tree) and indented outline list; can be organised by phase or by deliverable.

A good WBS has 3 to 6 levels, and each work package is typically 8 to 80 hours of work.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does the 100% rule of a WBS require?
   A. Every element must be 100% complete before the next starts
   B. Each work package must take exactly 100 hours
   C. The WBS must contain all work, and the children of an element add up to 100% of the parent
   D. The project must be completed in 100 days
   Answer: C. The WBS includes all the work in scope, and child elements together equal 100% of the parent. Work not in the WBS is outside the project. (Key point: 100% rule)

2. How should WBS elements be named?
   A. As dates of completion
   B. As names of the people responsible
   C. As verbs describing activities, such as 'Design'
   D. As nouns describing deliverables, such as 'Design document'
   Answer: D. A WBS is deliverable-oriented, so elements are nouns, not activities. (Key point: Deliverable orientation)

3. What is the lowest level of a WBS called, and what is it used for?
   A. Milestone, used for payments
   B. Control gate, used for approvals
   C. Work package, used for estimating, assigning and scheduling
   D. Baseline, used for variance analysis
   Answer: C. The lowest WBS level is the work package, which is the basis for estimating cost and time and assigning responsibility. (Key point: Lowest level)

4. Which combination forms the scope baseline?
   A. RACI chart, WBS and risk register
   B. Scope statement, WBS and WBS dictionary
   C. Charter, budget and schedule
   D. WBS, network diagram and Gantt chart
   Answer: B. The scope statement, WBS and WBS dictionary together form the scope baseline. (Key point: Scope baseline)

## Related in ICT Project Management

- [Statement of work](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Astatement-of-work) — ICT Project Management, chapter 7

## Related in other subjects

- [Work breakdown for frame structure quantities](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Awork-breakdown-quantity-frame) — Estimating and Costing, chapter 2
- [WBS definition and importance](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Awbs-definition-importance) — Project Engineering, chapter 3, asked 8×
- [WBS with example, levels and code](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Awbs-example-levels-code) — Project Engineering, chapter 3, asked 4×
- [Importance of WBS for project planning](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Awbs-importance-in-planning) — Project Engineering, chapter 3