UPI Study › Courses › Project Management › Free lessons › Lesson 3.4 Free with a free account
Work Breakdown Structure: Design and Practical Examples
Project Management · Chapter 3: Building a Comprehensive Project PlanSection 3.4 · lesson 18 of 7314 min · free with a free account
Free preview
Create a free account to keep watching
It takes a minute and costs nothing. Your free account unlocks all of Chapter 1 and 3 more lessons of Project Management.
Lesson complete
Earn the 3 college credits for Project Management
Enrolling adds a quiz after each lesson, the graded work and the official transcript. Recommended for credit by NCCRS.
Next lesson: Dependencies, Contingency Planning and Phase Gates →← Resource Management Planning and AllocationNext lesson: Dependencies, Contingency Planning and Phase Gates →
In this lesson
Breaking project scope into deliverables that can be priced and tracked.
- Define a work breakdown structure and apply the 100 percent rule
- Describe a well-formed work package and a WBS dictionary entry
- Compare deliverable-based and phase-based structures and decimal numbering
- Roll up estimates and size work packages using common heuristics
Free study notes
Get this lesson's notes by email
The key points and 4 practice questions with answers, in your inbox. One email, free.
One email. Unsubscribe in one click.
Transcript
Everything said in the video, section by section (1,854 words). Read along, or search it.
Opening Question
Pricing a One-Sentence Pavilion
A neighborhood garden association wants an open-sided pavilion, with bench seating, a lockable tool store, and rainwater collection. Can you price that sentence? Hand it to one person? Tell, next month, how far along it is? Not as one lump. A sentence that size hides its own problems. A work breakdown structure, or WBS, is how a project cuts its scope into pieces it can price, assign and track.
Definition
Decomposing Scope Into Deliverables
Formally, a WBS is a hierarchical decomposition of a project's total scope into smaller and smaller pieces, organized around what the project will produce. Each piece is a deliverable: a measurable, verifiable product or result, like a poured concrete footing, or an approved schedule. Teams decompose for four practical reasons. Manageability: a small piece can be held in mind, and its problems noticed. Estimating: a small piece can be compared with similar work. Assignment: clear edges let one party own it. And control: progress can be measured only against pieces small enough that done and not done can be told apart. One caution. A WBS shows what will be produced, not when. The order of siblings on the page carries no scheduling meaning.
Key Rule
The 100 Percent Rule
Decomposition divides an element, level by level. The single element at the top, level one, is the whole project. An element directly above another is its parent; those beneath it are its children. Each level restates the same scope in finer detail. Where do you stop? When the lowest piece can be estimated, assigned to one accountable party, and tracked from started to finished. The principle that keeps it honest is the 100 percent rule: the children of an element account for all of its scope, and nothing beyond it. If the children cover less, scope is omitted, and surfaces later as unplanned work. If they cover more, or two siblings overlap, work was added without approval, or counted twice. At the top, the rule is anchored to the scope statement. Every in-scope deliverable traces to an element, and nothing out of scope appears anywhere.
Method
Checking Children Against the Parent
Applying the rule is a matter of careful reading. For each parent, write in one sentence what it includes, taken from the scope statement. List its children. Is anything in the parent's sentence covered by no child? That's an omission. Does any child fall outside the sentence, or repeat a sibling? That's excess, or overlap. Numbers can help: a big gap between the children's total and an independent estimate for the parent is worth a look. But it's only a signal. The rule is about scope, not hours, and only comparing words against the scope statement tests it.
Work Packages
Owner, Estimate and Completion Evidence
The lowest element is the work package: where work is estimated, assigned and tracked. Everything above it is a summary element, whose estimate is a roll-up. A well-formed work package answers three questions. Who is the single owner? What is the estimate of effort, duration or cost? And what is the completion evidence, something an observer can inspect, like a level footing, or an issued document? A package that can't answer one of these needs more decomposition, or a clearer description.
WBS Dictionary
An Entry for the Concrete Footings
Names alone can't settle what a package contains. The WBS dictionary holds one entry per element, detailed enough to remove ambiguity. Take the footings. Identifier, 1.1.1.2. Name: concrete footings poured. Description: four poured footings, cured and level, including marking out and formwork. Excludes clearing and leveling, which belong to 1.1.1.1. Responsible party: the volunteer builder lead. Assumptions: the site is cleared and level first, and the concrete arrives ready-mixed. And a pointer to the acceptance criteria, written elsewhere, so each criterion is written once, and can't drift out of step with a copy. That exclusion sentence enforces the 100 percent rule between siblings: it points shared work to the element that owns it, so nobody claims it twice.
Quick Check
A Catering Branch With Gaps
Quick check. A parent element reads: event catering, meaning food, drinks, and serving staff. Its children are: food prepared, drinks supplied, and venue booked. Measured by the 100 percent rule, what's wrong? Pause, and decide. Both: a gap and an extra piece. Serving staff are in the parent's sentence, but no child covers them. And venue booking isn't catering at all. It belongs under another parent, or it's work nobody approved here.
Design Choice
Deliverable-Based Versus Phase-Based
The big design choice sits at level two. A deliverable-based structure makes level two the main products. A phase-based one makes it the stages, like design, build and handover. Both can be correct, if every piece of work sits under one parent. They differ in what they make easy to see. Deliverable-based mirrors the scope statement, so completeness is easy to check, and one owner can hold a product from start to finish. But it shows nothing about stage, and work that joins two products can fall between branches, unless someone names it. Phase-based matches how many sponsors think, and suits approval stage by stage. But one deliverable gets scattered across phases, with split owners. It's also harder to check against a scope statement, and phase names invite vague entries like build. Some teams use a hybrid: deliverables at level two, phases lower down. Which should come first is disputed. Deliverable-first says scope is what will exist, and time belongs in the schedule, where it can change freely. Phase-first says that in exploratory work the products aren't known yet, and organizations that fund by stage need a structure that reports by stage. The empirical part asks which leads to fewer omissions or clearer ownership, and no measured result is offered here. The normative part asks whom the WBS should serve first.
Formats
Charts, Outlines and Decimal Codes
Two formats show the same structure. A hierarchical chart, a tree of boxes, shows breadth and balance at a glance, but gets unwieldy past a few dozen elements. An outline, an indented list, scales to hundreds of elements, edits quickly, and leaves room for dictionary fields, though its shape is harder to see. Each element gets a decimal number. Level one is 1, and each child adds a point and its own digit. So the digit groups equal the level. 1.2.2.1 is level four: a child of 1.2.2, descended from 1.2. Keep numbers stable, since costs and reports cite them, and retire deleted ones. Numbers carry no order of work: 1.3 doesn't follow 1.2 in time.
Worked Example
Building the Pavilion WBS in Stages
Now build the pavilion's WBS in stages. Stage one: a single level one element, the Garden Pavilion Project. Stage two: what must exist at the end? Site Ready, the prepared ground and water supply. Pavilion Structure, the frame and roof. And Pavilion Fit-Out: seating, store and signs. Then a fourth branch, Project Management. Planning, reporting, the permit and handover take real effort, so the 100 percent rule requires them. Stage three splits each again: ground preparation and water collection, frame and roof, seating and storage, signs, planning and control, permit and handover. Stage four divides each until the stopping test is met. That gives thirteen work packages, each with hours of effort.
Roll-Up
Summing Hours to 320
Now roll up the hours. A parent's estimate is the sum of its children's. Pavilion Structure: the timber frame is 64 hours. The roof is 40 for the covering plus 12 for gutters: 52. So 1.2 is 64 plus 52: 116 hours. The same sums give Site Ready 80, Fit-Out 60, and Project Management 64. The project total is 320 hours. A child's share is its estimate divided by its parent's, times 100. At the top: 25, 36.25, 18.75 and 20 percent, which add to 100. Shares adding to 100 only prove the sums were right, not that scope is complete. They do show where effort lies: management is a fifth, invisible without its branch.
Sizing Heuristics
How Big a Work Package Should Be
How big should a work package be? There are only heuristics: rules of thumb that usually work, but guarantee nothing. One is an effort band. Practitioners often quote roughly 8 to 80 hours, but no band is established as the correct one. Another is the reporting period rule: a package should finish within one or two reporting periods. The timber frame is 64 hours. A crew of four volunteers, eight hours a week each, gives 32 hours a week, so the frame takes two weeks. With weekly reports and a one-period rule, it's too big. So the team cuts it in two: frame base assembled, and frame raised and braced, one week each. Report every two weeks instead, and the same package passes unchanged. That's why these are heuristics, not rules. Teams size differently for good reasons. Tiny packages multiply tracking, big ones hide trouble, unfamiliar work is cut smaller, and contract milestones can fix some boundaries.
Debate
Full Decomposition or Rolling Wave
A related dispute: when to decompose in full. One side says take everything to work packages before work begins. Omissions are cheapest to fix on paper, and a complete baseline gives tracking something firm. The other side, rolling wave planning, details only near-term work, and keeps later work at a higher level, refining it as it approaches. The empirical question is how often distant detail gets redone. The normative one is how much effort to commit up front, and who bears the cost when plans prove wrong.
Common Mistakes
Four WBS Errors and Their Tests
Four errors account for many defective structures, and each has a simple test. Activity verbs instead of deliverables. Pour footings is an action; concrete footings poured is a result. Test: can you point to the thing that exists when it's done? Phases and deliverables mixed on one level, like design next to pavilion structure. Now the design has two homes. Test: do all siblings answer the same question? Omitted management work: planning, reporting, permits and handover, spent but never estimated. Test: is there a management branch, as concrete as the rest? And overlapping elements: if both owners do the work, it's duplicated; if each assumes the other will, it isn't done. Test: the dictionary's exclusion sentences.
Quick Check
Splitting a Ninety-Hour Package
Quick check. A package needs 90 hours. Its crew of three each gives 10 hours a week, and progress is reported weekly, under a one-period rule. Keep it whole, or split it? Pause, and decide. Split it. The crew gives thirty hours a week, so ninety hours takes three weeks, three reporting periods. Nine weeks would be one person working alone. Cut it into packages that each fit a week, so problems show at the first report.
Next Steps
Packages Feed Estimates and Activities
From here, the work packages feed everything else. Resource and cost estimates attach to them, so different people's numbers roll up to the same parents. Each owner named in the dictionary is the person the package is assigned to, and who reports on it. And each package is later divided into activities, actions with verbs that someone performs, then listed and sequenced. Back to the pavilion sentence: thirteen packages, each one priced, owned and trackable. The WBS says what must be produced; the activity list says what must be done, and in what order.
Key Takeaways
Deliverables, Rules and Dictionaries
To recap. A WBS breaks scope into deliverables, level by level, until each package can be estimated, assigned and tracked. The 100 percent rule: children cover all of the parent, and nothing more. The dictionary's descriptions and exclusions remove ambiguity between elements. And include management work, named as results, never as activity verbs.
About Project Management at UPI Study
Project Management (Business 230) is a self-paced online course of 73 video lessons in 12 chapters, from starting and defining a project to planning, budgets, scheduling tools, proposals, contracts, execution, monitoring, closure, teams and certification. It carries a NCCRS credit recommendation for 3 semester credits.
Every lesson transcript is free on pages like this one, and the videos are free with a free UPI Study account. Enrolling adds a practice quiz after each lesson, the graded work and final exam that earn the credit, lifetime access, and an official transcript on completion. UPI Study has helped over 130,000 students with college credits. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
Enroll now → Course details Download the syllabus All Business courses Every course with PRO →
Why take it here
Why students take Project Management with UPI Study
Where the credit goes
Universities that work with NCCRS
Project Management carries a NCCRS credit recommendation. These universities work with NCCRS; some are UPI Study's signed partners. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
Thomas Edison State UniversitySigned partner
University of the PeopleSigned partner
Charter Oak State CollegeSigned partner
Strayer UniversitySigned partner
Columbia Southern UniversitySigned partner
Indiana TechSigned partner
Penn StateWorks with NCCRS
Southern New Hampshire UniversityWorks with NCCRS
SUNYWorks with NCCRS
+many more cooperating universitiesFind my college →Find my college → Not listed? Ask Athena in the corner of this page, or book a 15-minute call.
FAQ
Questions students ask us
About Work Breakdown Structure: Design and Practical Examples
What is the 100 percent rule in a work breakdown structure?
What is a work package in a WBS?
What is a WBS dictionary?
What are common mistakes when creating a work breakdown structure?
About the Project Management course
How many college credits is Project Management?
How much does Project Management cost and what is included?
Which universities accept UPI Study credits?
How long does Project Management take?
How are the exams done?
How do my credits reach my college?
Ready for the full course? Earn 3 credits in Project Management.
73 video lessons, a quiz after each one, and the graded work that earns the credit. Recommended for credit by NCCRS.
3 credits · NCCRSEnroll →