I am often asked what is the best way to begin to plan out a project such that one can understand project complexity, as well as, accurately estimate project scope, schedule and budget. If this question was asked to several project managers, I am confident that there would be several different opinions. In my opinion, the best way to accomplish this task to utilize the Project Scope Statement and the Requirements Documentation to create a Work Breakdown Structure (WBS).

To calibrate on what is a Work Breakdown Structure (WBS), the Product Management Body Of Knowledge defines it as: “A hierarchical decomposition of the total scope of work to be carried out by the project team to accomplish the project objectives and create the required deliverables”. It is similar to a company organization chart except instead of highlighting who is in what position within the company, it details what tasks must be accomplished to complete a project from the highest to the lowest planned level.

It is not uncommon to be asked what is the meaning of the word “decomposition”. I assure you with regards to project management it has nothing to do with the human body! This means the project scope is logically divided and subdivided from the top down into smaller, more manageable parts called “Work Packages”. Work Packages define project work to its lowest level so project cost, time duration and resource requirements can be calculated.

You may ask what is a Project Scope Statement and Requirements Documentation. A Project Scope Statement is nothing more than than a description of the project scope, and major project deliverables, as well as, assumptions and constraints associated with the project deliverables. A Requirements Document is a description of how individual project requirements will meet the business need for the project.

Okay, so you want to construct a Work Breakdown Structure for your project and you understand what information is required to begin this process. But before you launch ahead into the work of creating a Work Breakdown Structure, understand the benefits it will provide you, your project team, project sponsor and project stakeholders.

I might also add that you should create a Work Breakdown Structure with your project team and individuals who best understand the nature of work to be accomplished. Doing it alone as a Project Manager is very risky because you are almost assuredly miss key tasks (work packages) which will have a negative effect on project planning, scope, schedule and budget.

So, what benefits can you expect from constructing a Work Breakdown Structure that will highlight project complexity, simplify project planning, assure achievement of project deliverables, provide better accuracy to plan resource requirements and help create a realistic project budget? A well constructed Work Breakdown Structure accomplishes the following:

  • Allows the Project team to structure a project into manageable deliverables (Work Packages)
  • Helps the Project team to avoid missing tasks to be completed within each work package
  • Facilitates a holistic look at a project to avoid down-stream issues like re-planning or re-work
  • Improves project planning accuracy for each work package: Cost, Duration, Resources, etc.
  • Clarifies assignment of roles & responsibilities required to complete each work package
  • Helps determine if internal or external resources will be required to complete work packages
  • Facilitates the identification of potential project risks making risk assessment easier
  • Establishes a baseline for project performance measurement and control
  • Provides the project team a logical workflow to properly plan out the project

It is important to understand that the completeness of a Work Breakdown Structure has a direct impact on how well a project manager can determine required resources, project budget and sequencing of project work. The Work Breakdown Structure is the engine that drives achievement of project scope, accuracy of project budget and schedule, as well as, identification mitigation of project risks.

Here are a few guidelines to help construct a Work Breakdown Structure:

Each Work Package should be given a unique numerical identifier to help track cost, time and resource allocation for it.

For example, if you are developing a Customer Relations Management Software Program, the highest level task determined by the decomposition process may be Planning. This would be represented on the hierarchical chart as “1.0 Planning”. Under this heading the first Work Package may be Determine CRM Performance Criteria. This work package would be labelled “1.1 Determine CRM Performance Criteria”. The second Work Package may be Finalize CRM Performance Criteria. This work package would be labelled “1.2 Finalize CRM Performance Criteria”.

The idea behind this best practice is that each work package has a unique numerical identifier to be used to estimate and track the cost, as well as, timing associated with completing it. For example if the Project Manager estimates that it will take 8 hours to Determine CRM Performance Criteria at a cost of $50 per hour, the estimated cost is $400. You now know the amount of hours and time to complete the work package.

The Project Manager can use this type of information to develop a bottoms-up project budget. They can also use this baseline data to compare actually hours expended versus what was budgeted, as well as actual cost versus budgeted cost.

One additional benefit of breaking down a project to this level is you can determine what human and physical resources ought to be assigned to the work package, at what cost and where you will acquire them. Will they be internal or external resources?

A Work Breakdown Structure should always be defined at least one level lower that what is required for management reporting processes. This helps to identify any sources of issues or variances. Generally the more detailed a Work Breakdown Structure, the more accurate the work estimates for costs, resource requirements, project schedule and project control.

A common rule of thumb on the size of each work package is the 4/40 or 8/80 Rule For example, the 4/40 Rule states that no task should be less than 4 hours or more than 40 hours in duration.

 If you want to take this exercise one step further, you can construct what is known as a Work Breakdown Dictionary. A Work Breakdown Dictionary is nothing more than a document associated with each work package detailing its deliverables, assumptions and constraints on how the work package cost and duration estimates were calculated. It also clarifies what human and physical resources are associated with the work package, why they are required and any cost associated with them. A Work Breakdown Dictionary is best used for very large and/or complex projects, as well as projects being run using an Agile form of project management.

A word of caution to project managers who plan projects using spreadsheet software or Gantt Charts versus constructing a Work Breakdown Structure. Spreadsheets and Gantt Charts are good for tracking cost and duration data and they can be used to assign work tasks, but they ought to be used to compliment the Work Breakdown Structure. These types of tools do not help visualize the size or complexity of a project. So be careful not rely on these tools as your primary tools to break a project down into manageable parts.

I mentioned earlier that as a project manager you should create a Work Breakdown Structure with your project team and individuals who best understand the nature of work to be accomplished. This will prevent missing any key tasks (work packages) which will have a negative effect on planning project scope, plan, schedule and budget.

A best practice to conduct this exercise is to do it with the project team, key project stakeholders and individuals most familiar with the type of work to be done as follows:

  • Give each participant two different colored 3M Sticky-Notes. One color will be for the top level categories and the other color will be for the tasks to be arranged under each top level category.
  • Ask participants to write on one of the colored 3M Sticky-Notes what they think are the top-level categories to define the project. For example Planning, Define Requirements, Design Components; Test Components, Agency testing, etc.
  • Once all participants have listed their top level categories stick them up on a wall. Come to a mutual agreement on what are the the top level categories that will define the project and put them in a logical order or execution. Eliminate any redundancy in the process of defining the top level categories.
  • Next have the participants write on the other colored 3M Sticky-Notes what they believe to be the required tasks under each top level category in order to successfully execute the project. These required tasks are the work packages mentioned earlier in this paper. Have the participants place their answers on the wall under each top level category. Eliminate any redundancy.
  • Work one top level category at a time to make sure all required tasks (work packages) are identified and to avoid participant information overload issues. Best to be thorough in developing each top level categories required tasks (work packages) versus having to constantly revise them because someone thought of a task after the fact.
  • After each top level category has been populated with the required tasks (work packages), prioritize each task (work package) in logical order from first task to be done to last task to be done. Have the participants come to mutual agreement on task (work package) prioritization.
  • Once you have identified each top level category and populated it with the prioritized tasks (work packages), you have a Work Breakdown Structure (WBS) that details the project from start to finish. You should transfer this information into a computer to make a digital version of it and assign numerical identifiers to each top level category and the tasks (work packages) underneath them.
  • With your Work Breakdown Structure complete, you can proceed to estimate the cost, time duration and resource requirements for each task (work package). You can also begin to think about whom on the project team ought to be assigned to own and complete each task (work package).

Three lessons learned from conducting this exercise to avoid any mishaps and mistakes:

  1. Take a picture of the Work Breakdown Structure constructed using 3M Sticky-Notes to make sure you correctly transfer it into a computer. You will never be able to repeat it from your memory.
  2. When the computer version of the Work Breakdown Structure is done, send a copy of it to every participant who helped to develop it and ask them to review it for completeness. Ask them to make sure the team did not miss any tasks (work packages). If the team did miss anything, now is the time to capture it, revise the Work Breakdown Structure and send it out a second time for team approval.
  3. Once the team who helped develop the Work Breakdown Structure is in agreement that it is solid and realistic, show it to the project sponsor so they can see the how the project has been structured. Their agreement is essential to allow the project manager and project team to begin the process of writing the Project Management Plan.

 So there you have it, the basics of how to construct a Work Breakdown Structure. This is a critical tool for a project manager to use to plan a project for successful completion, as well as, to examine actual versus budgeted projects performance. I think it is the best tool a project manager has to ensure project success, project stakeholder support and to coach his/her company to exhibit excellence in project management.

They say: “The Devil is in the Details” If true, a Work Breakdown Structure keeps the devil from messing-up the details!


If you are interested in taking a deep dive into project management, you can also check out this The Ultimate Guide to Work Breakdown Structure by ProjectManager.com

Richard Broo

Principal/Founder, True North PMP Consulting, Inc.

Richard has over 40 years of company leadership and project management experience. He delivers commercial, technical and operational efficiencies for companies across different industries helping them improve competitive differentiation, client value and profitability.