Rethinking the Work Breakdown Structure – Part 2.2: The Structure of Breakdown

by | Sep 2, 2021 | Breakdown Structures | 0 comments

In the last post, I looked at the narrative of Breakdown Structures and how confused it is.

In this post, expand on the second pivot point towards improving Breakdown Structures in general, and the Work Breakdown Structure in particular. This point is to create a clearer understanding of what we are breaking down in developing a WBS.

We unpack this concept of breakdown into three areas:

  1. Neither work nor deliverables have an inherent structure to break down.
  2. How can we determine this structure and use it to break down
  3. The “stuff” we’re breaking down has to be decomposable.

Work has no inherent structure, so there’s nothing to break down – same with deliverables.

The WBS is used to aggregate work values into a hierarchy of categories. But the question remains: “Are we breaking down work?

The answer is an unequivocal no. We are “lumping and splitting” other elements of the project to which we will add work estimates.

This answer puts the notion of the WBS transitioning from a “task/activity” orientation to a “deliverables” orientation in a different light. This dichotomy (and all its associated angst) is irrelevant.


Because work has no inherent structure in and of itself and cannot be “broken down”. The same goes for deliverables: they are a product of work activities.

We’ve known for decades that work is amorphous and very difficult to define and manage.

Parkinson wrote about the expansion of work to fill the time available (“Parkinson’s Law” in “The Economist” – 1955). Drucker wrote about the factors that misdirect work-based outcomes (“Management by Objectives” in “The Practice of Management” – 1955). Those are just two people who nailed how the human factors of work can cause it to drift away from the intended goal.

Parkinson described the need for managers to hire subordinates and the fragmentation and duplication of work that results.

Drucker described the impact that a personal zeal for professional high standards and quality can result in wasted work.

“Workmanship is essential; without it no work can flourish; in fact, an organisation demoralises if it does not demand of its members the most scrupulous workmanship they are capable of. But there is always a danger that the true workman, the true professional, will believe that he is accomplishing something when in effect he is just polishing stones or collecting footnotes.” — Drucker, Peter. The Practice of Management (Classic Drucker Collection) (p. 106). Taylor and Francis. Kindle Edition.

You can try it yourself: take any work you are doing and try to subdivide it based on the activities alone. Each time you find the “joints” in the work activity, you’ll see that this is a function of a different element.

If we’re not breaking down activities or deliverables, what elements are we breaking down? First, we need to determine the structure we use to “split”.

How can we determine the structure?

The problem with the traditional Work Breakdown structure narrative is that it does not provide any coherent or detailed description of the structure that we are “breaking down”. In a 214-page Practice Guide for WBS published by PMI, approximately four pages are devoted to how to do it; and these four pages are very high-level, repetitive and lack specifics.

This guide includes about a half-page each on the “Top-down” and “Bottom-up” approaches, all highly generic with an extremely narrow scope. For example, this guidance completely ignores the “types” of breakdown described in later sections. (See the next section of this post, below)

“Top-down” and “Bottom up” are not mutually exclusive alternatives. Both approaches are essential parts of the WBS process. We perform both repeatedly as we go through the development and refinement.

The “Top-down” approach involves “decomposition”. The “Bottom-up” approach involves “grouping”. We need to dig into the details of decomposition and grouping to provide better guidance on how to do them both and in what circumstances.

We need to understand and identify “leading” structures and what are “lagging” structures.

Leading structures are those that we need to work on before we can identify any work packages. We use leading structures in the “top-down” approach.

We can apply lagging structures to elements already broken down to a level where we can estimate work. This grouping approach enables new insights, greater precision and identify missing or overlapping definitions.

We use lagging structures in the “bottom-up” approach.

By implication, this means that we need a better definition of the “100%” rule.

David Weinberger described this as “Lumping and Splitting”: the “top-down” approach “splits” elements into more fine-grained ones. “Lumping” (as in “lumping together”) is the “bottom up” approach.

What is the “stuff” we break down?

The Breakdown Structure narrative does not provide a coherent definition of the “stuff” that we break down.

The context of work determines its structure. What are we working on, using what resources, and within what structure and under what constraints?

Within projects, there are a huge array of elements that make up a project’s context, including but not limited to:

  • Resources: Any project consumes or uses materials, processes, people, knowledge, systems and technology.
  • Structural Frameworks: A project operates within multiple structural frameworks, e.g. organisation, government, social.
  • Constraints: all projects operate within some constraints: e.g. legal, time, finances.

All of these elements have some level of intrinsic structure – even if elementary.

But what do we get from the traditional narrative? The most conventional / established source is PMI in their WBS Practice Standard. This practise guide lists 8 “types” of breakdown (7 in a table and one – location – as an emerging afterthought). But little is done to examine what these “types” are and what structure they have.

The practise guide provides a few examples, but these are illustrations from a project lifecycle perspective. There is no analysis of these “decomposition types” structural divisions: just a 1-sentence “focus description” and a few examples.

Leaving aside the fact that 2 of these are work-related (activity and deliverable), this is a minimal set of elements and limited coverage of what decomposition can occur. Most of these are not suitable for decomposition and are candidate attributes to be used for grouping, and thus only valuable for the bottom-up approach.

Rad, 1999 described a set of 11 “division bases” which govern “the transition from each level of the WBS to the next. We’ll explain these bases in more detail in a future post.

Of the 11, activity and deliverable are included, so this leaves nine that are potentially useful.

I’ll cover more on this in future posts, but we need to pivot towards a clearly explained set of elements that we can break down(or group up) with more precise guidance on exactly how to do this.

The Bottom Line

The traditional WBS narrative (and, by extension, all breakdown structures) is extraordinarily vague and incoherent on the subject of the concepts of “breakdown” and on the “stuff” we are breaking down.

The traditional WBS narrative mentions these other decomposition structures, but there is little guidance on using these or when. The conclusion is that any aspect of the context is available for any tree level at any time.

We need to develop more valuable and precise guidance on these two elements, which are, after all, the very core of Breakdown structures.

Check out Part 2.3 “Leveraging a Broader Range of Tools”


Sign up for the AOP Newsletter

Each week Adam writes about interesting and varied topics for Project Managers everywhere and curates useful articles, books and papers from other sources.