WBS in P6

The work breakdown structure (WBS) is the spine of every schedule in Oracle Primavera P6. It decides how activities are grouped, where dates and costs roll up, and how easily anyone outside the contractor's office can read the file. For an owner, the WBS is also the one part of a contractor's P6 schedule you can specify in advance, so that every baseline and update arrives in a shape you can compare, month after month, against your own master schedule.

Learning outcomes

• Explain what a WBS is in P6 and how it sits between the EPS, the project and its activities.
• Add, edit and reposition WBS elements in the Work Breakdown Structure window of P6 Professional.
• Describe how WBS codes, the code separator, anticipated dates and roll-up work.
• Write an owner WBS standard for a contractor schedule and check a submission against it.

The lesson

What the WBS is in P6

Oracle defines the WBS as a hierarchy of the work needed to complete a project, broken into levels of increasing detail [1]. Three properties matter for everything that follows:

• One WBS per project. Each project in P6 has its own WBS. Unlike the EPS and OBS from Lesson 3, which are enterprise data shared across the database, the WBS belongs to a single project [1].
• The project is the top node. The top WBS element is the project itself [1]. When you open the WBS window you see the project ID at the top, with every WBS element beneath it.
• Elements hold activities, children, or both. A WBS element can contain lower-level elements, activities, or a mix [1]. Activities sit at the lowest level of the WBS and are the smallest unit the project manager deals with directly [13].

Each WBS element can also carry its own calendar, earned value settings and responsible manager, an OBS element that is accountable for the work in that branch [1]. So the WBS is not just folders: it is where P6 summarizes dates, units and costs.

Where the WBS fits

Figure 1 puts the pieces in order. A useful test: if a node exists to organize the portfolio, it belongs in the EPS; if it exists to organize the work of one project, it belongs in the WBS.

Building the WBS in P6 Professional

Open a project, then choose Project, WBS, or click the WBS icon on the Project toolbar [2]. The Work Breakdown Structure window can show a table, a chart or a Gantt chart on top; switch between them under View, Show on Top or from the Display Options bar [14]. The bottom pane, WBS Details, is opened with View, Show on Bottom, Details [2].

To add an element [3]:

1. Select the element that will be the parent (the project node, for a level-1 element).
2. Click Add on the Edit toolbar, or choose Edit, Add. P6 creates the new element one level below the selection.
3. On the General tab, enter the WBS Code and WBS Name, set the Status, pick a Responsible Manager and, if you are still planning, enter Anticipated Start and Finish dates.
4. Use the arrows on the Move toolbar to shift the element up, down, left or right in the hierarchy [2][3].

The General tab is where most review findings come from. Status can be Planned, Active, Inactive or What-If [5]. The Responsible Manager is an OBS element, chosen with the selector beside the field [4][15]. Right-click and choose Expand All to see the whole tree at once [2]. Other tabs hold notebook topics, budget log, spending plan, budget summary, WBS milestones, work products and documents, and earned value settings [16].

Screenshot to come

Codes and the separator

Each element has a short code at its own level. P6 joins the codes down the tree with a separator character, so element 2 under element 3 shows as 3.2, and its full code includes the project ID in front. The separator for a project is set on the Settings tab of Project Details, in the field for the character that separates WBS code levels [6]. The database-wide default comes from the code separator in Admin Preferences, which P6 also applies as the default WBS separator in all projects [7]. Pick one separator for your organization and leave it alone; mixed separators make imported files hard to compare.

Keep codes short and stable. If a code changes between updates, every month-on-month comparison of that branch breaks.

Dates, budgets and roll-up

Before a WBS element has activities, its Anticipated Start and Finish are the only dates it has. They are planning values, untouched by scheduling. Once activities are added, the element's start and finish roll up from the earliest activity start and the latest activity finish beneath it [3]. Budgets and funding can also be set at WBS level for top-down planning and passed down to projects and activities [10].

Summarize to WBS Level on the Settings tab caps how many WBS levels are stored in summarized data [6]. A WBS element can also take performance percent complete from weighted WBS milestones [11], which are not milestone activities (see Lesson 7).

Using the WBS in the Activities window

Every activity points to a WBS element through the WBS field on the General tab of Activity Details; click the browse button to change it [12]. An activity left without a specific element sits at the project node, which is usually a sign of a rushed schedule.

To read the schedule by WBS, choose View, Group and Sort By in the Activities window and set Group By to WBS. For hierarchical fields such as WBS, the To Level setting shows all levels or stops at a level you choose, and the Indent option shows the bands as a tree [8]. Where several projects share the same structure, you can group by WBS path, which groups identical WBS levels across projects and leaves out the project node [9]. That option is the one owners use to compare a baseline and an update side by side.

Northgate worked example

Northgate Distribution Centre (fictional) is a 12,000 m² tilt-up warehouse in Vaughan, Ontario. Halvorsen Builders Ltd. (fictional) holds a CCDC 2-2020 stipulated price contract with Northgate Logistics Inc. (fictional) and schedules in P6. The owner's master schedule is in Microsoft Project, built on a ten-element summary WBS. Halvorsen's baseline is due Wed Feb 10, 2027 and will be imported as NDC-BL00 into the owner's NDC.SUB branch (see the Northgate fact sheet).

The owner's WBS standard

Northgate's schedule specification fixes level 1 of the contractor's WBS. Directly under the project node, the baseline and every update must carry ten elements, coded 1 to 10, named exactly as in the owner's summary WBS. Halvorsen is free to add level 2 and below to suit how it builds, as long as each lower element sits under the right level-1 parent and its codes stay stable from update to update. The separator is a full stop.

Why level 1 is fixed

The owner's master schedule in Microsoft Project uses the same ten summary elements. Fixing level 1 in the contractor's P6 file means the owner's scheduler can group any submission by WBS to level 1, read ten summary bars, and compare them line for line with the master schedule. Milestones M4 (foundations and slab complete, Fri May 14, 2027) and M5 (tilt-up panels erected, Fri Jun 25, 2027) then sit naturally at the ends of elements 3 and 4.

Checking NDC-BL00 on receipt

When the baseline arrives, the owner's scheduler opens NDC-BL00 read-only and works through four checks:

1. Level 1 matches. In the WBS window, Table view, all ten codes and names are present, in order, directly under the project node.
2. Nothing sits on the project node. In the Activities window, group by WBS and look at the project band. Any activity there has no real WBS home.
3. Lower levels are under the right parent. Slab work under 3, not 4; panel erection under 4, not 2.
4. The separator and codes are clean. A full stop throughout, no spaces, no duplicate names under different codes.

For each update, the scheduler repeats the checks and groups baseline and update by WBS path, so added, renamed or moved elements stand out.

Screenshot to come

Screenshot to come

Owner's move

The WBS is the cheapest place for an owner to shape a contractor's schedule, because it is set before the baseline exists.

• Put the WBS in the specification. State the level-1 codes and names, the separator and the rule that codes stay stable between updates. Leave lower levels to the contractor, with a rule that each sits under the right parent.
• Align it with your master schedule. Use the same summary WBS in your Microsoft Project master and the contractor's P6 file. Then a WBS level-1 grouping in P6 maps straight onto your summary tasks.
• Check structure before logic. On receipt, check the WBS first. A baseline with a broken WBS is hard to review for logic, float or cost loading. Our schedule review guide covers the checks that come next.
• Reject a resubmission that restructures silently. A changed WBS between the baseline and update 1 needs a written explanation. Our post on setting and locking a baseline explains why the accepted structure should be frozen.

Common mistakes

1. Using the WBS as a filing cabinet for versions. "Rev 2" and "What-if" branches belong in separate projects under the EPS, not inside a project's WBS.
2. Building the WBS by trade only. It hides the deliverables. Organize by deliverable and area; put trades in lower levels or activity codes.
3. Leaving activities on the project node. They do not roll up into any element, so they vanish from every summary view the owner reads.
4. Trusting anticipated dates. Once activities exist, anticipated dates are not what drives the WBS dates [3]. Review the rolled-up dates.
5. Renumbering codes mid-project. It breaks every comparison against the baseline and makes claim analysis slower and costlier.

Quick quiz

1. In P6, the top element of a project's WBS is:

   1. The root EPS node
   2. The project itself
   3. The first level-1 WBS element
   4. The responsible manager's OBS element

2. Where do you add a WBS element in P6 Professional?

   1. Enterprise, Enterprise Project Structure
   2. Project, WBS, then Edit, Add
   3. Admin, Admin Preferences
   4. Tools, Schedule

3. A WBS element has activities assigned. Its start date comes from:

   1. Its Anticipated Start field
   2. The project's planned start only
   3. The earliest start of the activities beneath it
   4. The data date

4. The Responsible Manager on a WBS element is:

   1. A resource
   2. An OBS element
   3. A user login
   4. An activity code

5. Northgate wants to compare its baseline and update 1 branch by branch. The most useful setting is:

   1. Group by WBS path across both projects
   2. Sort by Activity ID
   3. Group by calendar
   4. Change the code separator

Show answers and explanations

1. B. The top-level WBS element is the project (or EPS node) it belongs to [1].
2. B. Open the Work Breakdown Structure window from Project, WBS, select the parent and click Add [2][3].
3. C. Anticipated dates are for planning; once activities exist, WBS dates roll up from the earliest start and latest finish [3].
4. B. The Responsible Manager field holds an OBS element chosen with the selector [4][15].
5. A. Grouping by WBS path groups identical WBS levels across projects and leaves out the project node [9].

Key terms

Work breakdown structure (WBS)

A project's hierarchy of work, from the project node down to the elements that hold activities.

WBS element

One node in the WBS, with a code, name, status, responsible manager and optional anticipated dates.

Project node

The top of a project's WBS, which is the project itself.

Code separator

The character that joins WBS codes across levels, such as the full stop in 3.2.

Anticipated dates

Planning dates on a WBS element that apply only until activities are assigned.

WBS path

The chain of WBS levels above an activity, without the project node; used to group several projects that share a structure.

WBS standard

An owner's specified codes and names for the upper WBS levels of a contractor's schedule.

References

1. Oracle. Work Breakdown Structure. Primavera P6 Professional Help, Version 26.
2. Oracle. Work Breakdown Structure window. Primavera P6 Professional Help, Version 26.
3. Oracle. Add a WBS element. Primavera P6 Professional Help, Version 26.
4. Oracle. General tab - WBS Details. Primavera P6 Professional Help, Version 26.
5. Oracle. WBS status types. Primavera P6 Professional Help, Version 26.
6. Oracle. Settings tab - Project Details. Primavera P6 Professional Help, Version 26.
7. Oracle. General tab - Admin Preference dialog box (P6 Professional Only). Primavera P6 Professional Help, Version 26.
8. Oracle. Group activities by hierarchy. Primavera P6 Professional Help, Version 26.
9. Oracle. Grouping activities by WBS path. Primavera P6 Professional Help, Version 26.
10. Oracle. Using a WBS for top-down planning. Primavera P6 Professional Help, Version 26.
11. Oracle. Using weighted milestones in the work breakdown structure. Primavera P6 Professional Help, Version 26.
12. Oracle. Change an activity's work breakdown structure assignment. Primavera P6 Professional Help, Version 26.
13. Oracle. Activities. Primavera P6 Professional Help, Version 26.
14. Oracle. View the WBS. Primavera P6 Professional Help, Version 26.
15. Oracle. Assign an OBS element to a WBS element. Primavera P6 Professional Help, Version 26.
16. Oracle. WBS Details. Primavera P6 Professional Help, Version 26.

Verified on November 4, 2026.

Next lesson in this trackActivity types: Task, LOE, WBS summary, milestones