Project Management – Work Breakdown Structure (WBS)

Work Breakdown Structure

Work Breakdown Structure is a method of systematically breaking down (or decomposing) project related activities. It starts with a high level, all encompassing view and goes through multiple levels of decomposing to reach more practical/achievable tasks known as work packages.

Each work package has a time and duration associated with it. The level of detail of a work package is dependent on the complexity of a project. WBS helps in clear identification of tasks, time required to complete, resources & the costs associated with them.

See below a sample WBS that depicts the WBS for a project  undertaken to merge two production facilities.

  • Below WBS image shows a sample of all aspects of the project.
    • TASK NAME column shows individuals tasks that are divided and sub-divided to achieve the smallest possible work package in each section
    • DURATION column shows the time associated with each of the tasks
    • START and FINISH columns show the start time and end time for each task
    • PREDECESSORS columns shows the dependencies between tasks i.e. which tasks need to be completed in order for the following tasks  to be actioned
    • RESOURCE NAMES column shows the associated human resource with each task
    • COST column shows the cost of each of the item

The wire diagram is a visual depiction of connections and inter-dependencies between work packages and the associated resources.

WBSI will be breaking down each of the columns to share more information about it.

This column shows how one big activity is broken down into simpler, more direct tasks


See below a sample WBS diagram showing the above activitiesWBS Diagram


The below image show Duration of tasks, Start and Finish dates, Predecessors (See Leads and Lags post to learn more about Predecessor/Successor relationship), Resource Names, and Cost associated with each activity.


The below image shows a snippet of a few tasks and the associated time, resource and cost.


The above diagrams show each task (line item) has a specific start and end date. That is determined by the project manager and/or the project team, based on when certain activities are expected to happen during the course of that project. Once those dates are set, the total duration for that task is determined.  For example, task number starts on 1/9/2017 and ends on 2/3/2017, so the total number of days (excluding weekends) is 20.

Predecessor and Successor connections show the dependencies between tasks. For example, task (line 7), has line 6 has a predecessor, which in turn has lines 4 and 5 as it’s predecessors. These dependencies determine the sequence in which activities need to be completed. (See more on that in the Leads and Lags blog post).

Resource Names shows which human resource is associated with that corresponding task. (Go to the post on RACI Chart to see further breakdown of responsibilities)

Each line item has an estimated cost assigned to it. Depending on the activity some tasks cost more than the others.

Points to highlight

Duration & Start-Finish Dates:
It is VERY IMPORTANT to determine an activity duration based on it’s start and end date, keeping in mind OVERLAPPING dates/timeframe.

For example, task 1.2 – Managerial Approvals in total is suppose to take 30 days. If you see, tasks 1.2.1 and 1.2.2 each take 30 days… so just looking at those two tasks, it should take task 1.2, 60 days??? That is wrong. If you look at the corresponding dates, both the activities are suppose to start and end on the same dates i.e. activities done in parallel. Hence, you account for only 30 days and not 60 days.

Further, activity 1.2.3 is suppose to take 30 days (with the same start and end dates as 1.2.1 and 1.2.2) in total, with each of it’s sub-activities broken down into 5 days each, one after another (staggered dates within the 30 days time period), all adding up to 30.

This is how time is calculated and allocated for project related activities.

Costs for all the sub-tasks are added together to obtain the cost for the main task. For example, cost for task 1.2 – Managerial Approvals is a sum of cost for tasks 1.2.1, 1.2.2, 1.2.3, 1.2.4 and 1.2.5. Further, cost for 1.2.3 is a sum of costs for tasks to









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