ISO/DIS 21511

Second Edition

2025-12

Project, programme and portfolio management — Work breakdown structures

Management de projets, programmes et portefeuilles —Organigramme des tâches

DIS stage

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Contents

Foreword iv

Introduction v

1 Scope 1

2 Normative references 1

3 Terms, definitions and abbreviated terms 1

3.1 Terms and definitions 1

3.2 Abbreviated terms 2

4 Concepts 2

4.1 Context and principles 2

4.2 Purpose of a work breakdown structure 3

4.3 Hierarchical decomposition 4

4.4 Use dependency 5

5 Structure and composition of a work breakdown structure 5

5.1 Characteristics of a work breakdown structure 5

5.2 Setting up a work breakdown structure 7

5.3 Control of work breakdown structure 10

6 Uses and benefits of the work breakdown structure 11

6.1 Uses of the work breakdown structure 11

6.2 Benefits of the work breakdown structure 11

6.3 Work breakdown structure for technical control 12

7 Relationships to other project, and programme, and portfolio structures 12

7.1 General 12

7.2 Relationship to organizational breakdown structure 13

7.3 Relationship to contracts 14

7.4 Relationship to functional areas 14

7.5 Relationship to risk breakdown structure 15

7.6 Relationship to other structures 15

7.7 Relationship to portfolio structures 18

Bibliography 19

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This document was prepared by Technical Committee ISO/TC 258, Project, programme and portfolio management.

This second edition cancels and replaces the first edition (ISO 21511:2018), which has been technically revised.

The main changes are as follows:

• Alignment of terms and definitions with ISO 21506

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

The purpose of this document is to provide guidance on work breakdown structure for those individuals working in project, programme and portfolio management, involved in developing and using a work breakdown structure. This document incorporates practices to provide benefits for project, programme and portfolio planning and control, and provides guidance on work breakdown structure concepts, composition, and relationships with other structures.

This document is intended to complement ISO 21502 Project, programme and portfolio management — Guidance on project management, ISO 21503 Project, programme and portfolio management — Guidance on programme management, ISO 21508, Earned value management in project, programme and portfolio management and ISO 21512, Project, programme and portfolio management — Earned value management implementation guidance.

The target audience of this document includes:

1. practitioners of earned value management, project management, programme management and portfolio management;
2. management, sponsors and other governing bodies overseeing projects, programmes, and portfolios;
3. project, programme and portfolio management office professionals;
4. project, programme and portfolio stakeholders;
5. project and programme controls professionals;
6. academia including faculty, students and researchers;
7. developers of national standards, organizational standards and public policy.

This document can be tailored to meet the needs of any organization, so the organization can apply the concepts, standards, and practice of developing work breakdown structures.

Projects, programmes and portfolios should be aligned to the governance framework. Figure 1 provides an example of a context and environment within which a project, programme and portfolio can exist.

This document has additional information on what should be considered when developing a work breakdown structure for a project or programme, as well as information about uses and benefits for portfolio management.

Project, programme and portfolio management — Work breakdown structures

This document provides descriptions of applicable terms and definitions, concepts, characteristics, benefits, uses, integration and relationships in regard to work breakdown structures. This document does not provide guidance on the use of processes, methods, or tools in the practice of developing and using a work breakdown structure.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document, including any amendments, applies.

ISO 21506, Project, programme and portfolio management — Vocabulary

For the purposes of this document, the terms and definitions given in ISO 21506 and the following definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/

3.1.1

agile backlog

repository of work to be done, which can include progressive and prioritized features, potential work or improvements

3.1.2

capability

skills, resources, other personnel, and processes

3.1.3

epic

work broken down into specific activities based upon needs of customers or end-users

3.1.4

features

distinct functionalities or characteristics of the output/deliverable based on user needs

3.1.5

functional breakdown structure

modular decomposition of the process functions necessary to perform the work activities of a project or programme

3.1.6

Functional organization structure

management arrangement in which an organization is divided into departments or groups based on specialised areas of expertise.

3.1.7

integrated project team

multidisciplinary team structure including internal or external (contract) organizational personnel depicting as one project team

3.1.8

organizational breakdown structure

decomposition of the management team of an organization or of the management team that performs the work of a project or programme

Note: The organizational breakdown structure can include partners or subcontractors. It is used to illustrate the relationship between project or programme activities and the organizational units that will manage or perform the work activities.

[SOURCE: ISO 21506:2024, 3.40, Note added]

3.1.9

Project organization structure

formal arrangement of roles, responsibilities, reporting lines and levels of authority used to plan, manage, and deliver a project.

3.1.10

risk breakdown structure

decomposition of threats and opportunities for a project or programme

NOTE: Risk breakdown structure is a breakdown of categories or sources of risks.

[SOURCE: ISO 21506:2024, 3.78, Note added]

The following abbreviated terms are used in this document.

organizational breakdown structure OBS

project, programme or portfolio management office PMO

risk breakdown structure RBS

work breakdown structure WBS

The work breakdown structure provides structure for work done and work planned within an organizational context as shown in Figure 1, see Reference [4]. The context can be a singular organization or multiple organizations. A work breakdown structure should be used throughout a project or programme to establish the framework for the work of the project or programme. The work breakdown structure establishes a framework for how the work should be managed, with the intersection of work breakdown structure with organizational breakdown structure being the control account. The structure should provide a framework for decomposing 100% of the work defined by the project or programme scope.

Figure 1 — An example of project, programme and portfolio alignment within an organizational context

The work breakdown structure should provide a hierarchical decomposition of elements to the level necessary to plan and manage the work to satisfy the project or programme objectives, achieve the stated outcomes and realize the planned benefits.

The work breakdown structure should be decomposed to assist in the achievement of the project or programme objectives, outcomes and benefits. Each child work breakdown structure element should provide a more detailed decomposition of the project or programme scope of the parent work breakdown structure elements. Work breakdown structures can be product-oriented, deliverable-oriented or result-oriented; and additionally, can be focussed on project or programme phases, disciplines or locations. The entire work of the project or programme should include work to be done by the project or programme management team, project or programme team members, subcontractors, and other stakeholders.

The purpose of a work breakdown structure should be to enhance and support the management of a project or a programme by enabling the following:

1. decomposition of the scope into smaller elements of work to enable the management and control of the project or programme scope, resources and time;
2. enhancement of communication by providing a common framework for use by stakeholders when describing and analysing the scope and performance;
3. communication on the benefits resulting from various project or programme elements;
4. performance data summing up for strategic level such as portfolio reporting and analysis support for portfolio metrics;
5. elements with common identifiable characteristics, such as codes, to allow identification of areas of potential for improvement or coordination.

The hierarchical decomposition should include 100% of the work contained in the scope of the project or programme. Where a parent element is decomposed to child elements, aggregate of work defined by the child elements should represent 100% of the work contained in the parent element. The higher-level element is called the parent.

The parent – child convention describes the relationship. Within the hierarchy a single element can simultaneously be the parent of a number of child elements and the child of a higher-level element. Work can be broken into time elements, phases, gates, milestones or other grouping defined by the project or programme and allowed by the governance documentation for the organization, project, or programme. The decomposition should end with a deliverable or output, which can be a study, a design, a test, or other output. The decomposition can be driven by the need to change from one performing organization to another organization or team responsible for the work breakdown structure, such as moving from design to building test artefacts.

Some projects or programmes do not have either fixed scope or scope that is defined enough to be further broken down in the work breakdown structure decomposition. These projects can include a system of systems or agile development efforts. Decomposition techniques can include progressive elaboration, such as a rolling wave planning (see 5.2.1.2), where scope is (further) refined as the project or programme progresses. In this case, the work breakdown structure represents 100% of the scope of work known at the time of development of the work breakdown structure. As changes or further elaboration of scope are identified during the life cycle of the project or programme, those changes should be shown in the work breakdown structure.

Figure 2 — Example of graphical depiction of a hierarchically decomposed work breakdown structure

Figure 2 explains the hierarchical decomposition of a work breakdown structure as an example with 100% scope known at the given timeline of development. As the scope evolves, the work breakdown structure can change. The figure shows different phases of the project and segregations of the work involved in a project life cycle, for example project management, engineering, procurement, construction, commissioning, qualifications, validation and project closure.

The work breakdown structure is a flexible concept, and its design and overall structure should be adapted to the needs and governance of the project or programme, as well as how the efforts of the work elements are to be managed. The work breakdown structure should be tailored to the industry, type of project or programme, and other factors, such as project phases, major deliverables, scope, high-risk areas, organization performing the work and location of resources. The work breakdown structure should be flexible enough to accommodate alternative ways of organizing and representing the work.

Note: High-risk project and programme elements can influence the work breakdown structure, to allow management of risks and prioritization of risk treatment actions.

The characteristics of a work breakdown structure should be related to the scope of the project or programme for which it is being composed, see References [1] and [2]. The following are typical characteristics of a work breakdown structure:

1. can be represented by a variety of formats. The most common formats for a work breakdown structure are graphical, outline and tabular;
2. can be decomposed to different levels;
3. should be decomposed to a level that allows the necessary project or programme control to be imposed, see Reference [6] ;
4. should be composed of elements that can be assigned to a responsible person or entity;
5. should reflect the technical complexity, size, and other information, as deemed necessary for the scope;
6. should define the structure of the work and not the processes involved in accomplishing the work;
7. should provide a hierarchical decomposition of elements to the level necessary to plan and manage the work to satisfy the project or programme objectives and deliver outcomes and realize the planned benefits;
8. can assign budget or cost estimate to each work element;
9. can relate the contents of the elements into which the scope is decomposed to several considerations, such as industry standards, organizational governance, or contract terms and conditions;
10. should assign each element a unique identifier to distinguish one element from another.

The “100% rule” concept for decomposing the work should implement the guideline that the child element should be associated with its parent element (see Figure 3). Each element should have zero child elements or at least two child elements (see 4.3).

Each parent element of the project or programme scope is the sum of their children-elements only.

Figure 3 — Example of the 100% rule

The work breakdown structure should represent collective inputs of the project or programme team, including agreement upon decomposition of the work to be performed. Each change made to the work breakdown structure should be reviewed with the project or programme management team and the identified performing organization and performers within that organization.

Other considerations regarding the change should depend on when the change is made. Considerations prior to an approved baseline should be cost, schedule and technical scope, as well as risks, outcomes, planned benefits and value. Considerations after an approved baseline should be the same as prior to an approved baseline but also include contract terms and conditions that are impacted.

The work breakdown structure should be created and maintained until the final outputs have been completed and delivered or transitioned to the customer. The work breakdown structure should:

1. provide a systematic method for gathering cost data across projects and programmes;
2. be used within tracking systems as appropriate, such as a cost management system or earned value management system, see Reference [6];
3. serve to maintain the breakdown of the scope;
4. allow for project and programme status to be continuously visible and integrated;
5. serve to facilitate communication among project or programme team members, as well as with internal and external stakeholders;
6. allow for allocation of resources according to the work elements identified.

The work breakdown structure should be based on the needs of the expected outputs or outcomes, benefits or as stated in the statement of work.

If some project and programme elements are high-cost or high-risk, this part of the work breakdown structure can be defined to a lower level. The relationship of parent and child elements should be maintained.

The creation of a work breakdown structure can be accomplished by using one of three approaches:

1. top-down identification of the end deliverable and outputs, followed by successive subdivision of the work elements into detailed and manageable units;
2. bottom-up identification of elements of scope and merging, categorizing and ordering those elements in a hierarchy;
3. a combination of top-down and bottom-up approach.

The selection of the work breakdown structure should be in conjunction with the appropriate organizational governance procedure for work breakdown structures.

Progressive elaboration

Progressive elaboration can be useful when the full scope is unknown or subject to change, see References [6] and [7]. Such progressive addition of detail to the work breakdown structure should produce a more accurate work breakdown structure.

Progressive elaboration can involve one modification or successive modifications to the work breakdown structure. Scope can be progressively elaborated for each phase of the project or programme.

When using rolling wave planning (see clause 5.2.1.2) or progressive elaboration, a review of the work breakdown structure should be conducted to check that each element represents sufficient detail.

Rolling wave planning

Rolling wave planning can be used for the development of a work breakdown structure. A project can be planned as information becomes available or as phases of the project are developed. In other cases, the scope of work can change during the project. Rolling wave planning is a form of progressive elaboration that can allow for more detailed planning to occur as better information becomes available, as well as allowing for implementation up to the time where more detailed scope information is needed.

In applying rolling wave planning the work breakdown structure can be progressively elaborated during the life cycle of a project or programme. The level of detail provided by the initial work breakdown structure can vary.

Agile development

Agile development can use work breakdown structure terms, or it can use terms such as epics, capabilities and features in decomposing the work. The hierarchical breakdown can use an approach to mirror progressive elaboration of the technical scope of a work breakdown structure, see Reference [6].

An agile backlog shares many similarities to the planned work elements of a work breakdown structure. A backlog can also include potential work.

Agile development progress, such as completion of epics or features, should form the basis of technical percent complete for tracking earned value management cost and schedule. At the highest level of the work breakdown structure hierarchy, control accounts should summarize the major groupings of work and resulting outputs. At the lowest level of management, each work package should describe the deliverables and can include the resources and time needed to achieve those outputs.

Work breakdown structure elements can become the project or programme control points which further define one or more individual activities or tasks. The development of project or programme control points at the appropriate level of detail should enable the following:

1. definition of activities in the schedule;
2. elimination of overlaps by providing that a deliverable is represented in only one work breakdown structure element;
3. identification of the person responsible and their direct manager;
4. identification of the person to facilitate or initiate communication about the work breakdown structure element;
5. allocation of work to the project or programme team by dividing work breakdown structure elements to provide for accountability and control.

With the predictive approach, approved changes to the project or programme scope should be reflected in revisions to the content of one or more work packages.

With agile development, changes to the project scope can be expected to occur as the project or programme proceeds.

Work breakdown structure elements should represent the decomposition of the total project or programme scope into work activities (see ISO 21506:2024, 3.2). that create outputs or deliverables. The work breakdown structure elements should become the project or programme control points that can be further defined in contracts, plans, and schedules. Therefore, a decision about the desired level of control and insight should be made to guide the designation of work activities as work breakdown structure elements.

Portfolios, programmes and major projects can have a need for several work breakdown structures to be arranged in a hierarchal structure consisting of two or more levels. For example, a programme work breakdown structure under the control of the programme manager can define the need for a series of project work breakdown structures, each of which should be under the control of a project manager.

To create alignment among the various work breakdown structures in a hierarchy and facilitate the transfer of information needed for control and reporting purposes among the levels, there should be consistency of work element focus between the higher- and lower-level work breakdown structures.

Figure 4 shows one view of an organization with hierarchy and five levels of work breakdown structures, including portfolio, programme and project management. Level 1 is the organization, level 2 – the portfolio, level 3 – the programme management, level 4 – the project management and level 5 – the multi-discipline involved in an integrated project team.

Figure 4 —Hierarchy of work breakdown structures

A work breakdown structure can include or be accompanied by a work breakdown structure dictionary to accurately and precisely define what each work breakdown structure element represents.

The work breakdown structure dictionary should have a uniform structure and should be easily relatable back to the hierarchy containing elements being defined. As the project evolves, the work breakdown structure elements and their dictionary definitions should be updated to enable the work breakdown structure to remain relevant to project or programme stakeholders. An example of work breakdown structure elements and their work breakdown structure hierarchical relationships is shown in Figure 5. The elements have been classified as system, informative and service, which can be broken down into types, for example system elements can be system, sub-system, platform, facility and more.

NOTE Depending upon the work element, it can be further broken down to reduce complexity of developing work packages.

Figure 5 — Examples of types of work breakdown structure elements and their work breakdown structure hierarchical relationships

Work breakdown structure elements and dictionary definitions should be maintained to provide ongoing usefulness throughout the life cycle of the project or programme. If a progressive elaboration technique is used to identify project or programme scope, the new or changed elements should be proposed, agreed to, and incorporated into the work breakdown structure. Information items and records, known as artefacts, should document decisions to add, or edit, or delete the work breakdown structure elements related to any new or changed project or programme scope.

The work breakdown structure can be used to organize the elements of the agreed project or programme scope. Once these elements are identified, the work breakdown structure should provide a common foundation for communicating the types of resources and personnel needed to satisfy the project or programme scope, scope agreements, and resources consumed towards the performance of the work. If the work breakdown structure has evolved or has been progressively elaborated by adding, not deleting or otherwise changing the structure, then the structure can be used to analyse project or programme scope between life cycle phases. This use should provide continuity among projects to enable the project or programme to perform the life cycle analysis.

A benefit of the work breakdown structure can be through the reuse of its elements in management information items and related breakdown structures. This work breakdown structure element reuse strengthens the relationship between the project or programme scope and the work activities.

The work breakdown structure can act as an integrating mechanism between or among organizations, such as acquirers and suppliers and different functional resources, such as project management and engineering staff.

Another benefit of the work breakdown structure can be to enable consistent organizational responsibility assignment and reveal communication pathways between or among organizations, such as acquirers and suppliers and different functional personnel categories, such as project management and engineering. Figure 6 shows an example of how technical scope in a work breakdown structure can be a benefit when that work needs to be assigned to organizational elements.

Project or programme management team members can benefit from using the work breakdown structure elements as a basis for management activities, such as project planning, measurement, control, assessment and of risk, see Reference [7].

When multiple functional resource groups use the work breakdown structure elements as basis for their respective detailed activities, inputs, and outputs, the result can be readily integrated and assessed against the project or programme scope.

The work breakdown structure can provide the following benefits:

1. segregation of a project or programme into work elements, and clarifying the relationship among the work elements;
2. estimation of work element costs, risks, and durations;
3. facilitation of planning and assignment of management and technical responsibilities;
4. facilitation of tracking of technical performance, risks, resource allocations, and costs;
5. communication with stakeholders including management, customers, and suppliers;
6. provision of information and structure for the earned value management system;
7. provision of information and structure for value management;
8. provision of a link to the integrated master plan and the integrated master schedule for consistency, and analysis and assessment;
9. facilitation of a project or programme budget by providing a structure for allocation;
10. facilitation of configuration management of the work elements.

The work breakdown structure can be used for technical control by including technical design review and audit items within the work breakdown structure.

The work breakdown structure in Figure 6 shows the relationship between the work activities of the information element and the technical resource elements of the organization breakdown structure. The first control point should be a technical review of the definition information, such as need specifications, architecture descriptions, and design description to provide feedback.

Figure 6 — Example of a work breakdown structure relationship to an organizational breakdown structure

In project, programme, and portfolio management, there can be many different types of breakdown structures. Some breakdown structures can be developed and maintained at the organizational level, while others can be developed and maintained within projects and programmes or at the portfolio level.

Breakdown structures can be related to subject areas and can provide the project, programme, or portfolio manager and the team greater insight into the subject area and how it relates to the work of the project or programme. A work breakdown structure can be directly related to or integrated with other breakdown structures, such as an organizational breakdown structure, cost breakdown structure, risk breakdown structure, or other structures used by the project or programme to track or analyse various aspects of the project or programme.

The use of other breakdown structures in relationship to the work breakdown structure can be based upon:

1. complexity of the project or programme;
2. geographical, locational and functional aspects of a project or programme;
3. contractual relationships developed to accomplish the work;
4. benefits realization mapping;
5. specifications of the project or programme functions;
6. internal environmental factors, such as structure, culture and process maturity.

An organizational breakdown structure can be either a decomposition of the project, programme or portfolio organization, the functional management, or a combination of the two that represents management responsibility of the performing organization. The work breakdown structure and the organizational breakdown structure can be integrated. The integration should be done, so the lowest level of the work breakdown structure contains elements for which unique and unambiguous responsibility for delivery can be assigned and control points can be created. At the portfolio level, work can be assigned to either a project or a programme, therefore no control points should be shown at the portfolio level.

One example of the integration is shown in figure 7. The figure demonstrates the boundaries of functional organizational structure integrated in work breakdown structure relationship with a project, programme and portfolio organizational structure integrated with the work breakdown structure. Engineering, project or programme management office, or other offices as specified in the organization’s governance are part of the functional organization structure integrating into different engineering and design disciplines. Utilities further segregate into different disciplinary utilities dividing the work breakdown structure into control accounts or control points and work breakdown packages.

Figure 7 — Example of a work breakdown structure relationship to an organizational breakdown structure

Identification of scope and relationships in the work breakdown structure enables consistent organizational responsibility assignment, communication pathways, and performance measurement.

Projects or programmes that use contracts to accomplish the work, can use a contract work breakdown structure. The contract work breakdown structure can be depicted as part of the work breakdown structure by integrating it into the primary performing organization’s work breakdown structure or as a subordinate work breakdown structure for a particular work breakdown structure element. The purpose of the contract work breakdown structure can be to assist in the preparation of a request for information, request for proposal, request for quote, or other type of contracting document prior to the award of a contract. Other uses for the contract work breakdown structure can be the same as a work breakdown structure, such as integration with the project or programme risk breakdown structure or with a responsibility assignment matrix. The contract work breakdown structure can be rolled up into a portfolio of contracts structure.

Figure 8 —Example of a work breakdown structure relationship to contract breakdown structure

Figure 8 illustrates a relationship between a work breakdown structure and contract breakdown structure. The figure shows utilities as the prime contract with mechanical and allied mechanical packages as the sub-contracts. The work breakdown structure hierarchy shows utilities 1.1.1 as level 3 work breakdown and mechanical as level 4 work breakdown. This 1.1.1 utilities and prime contracts utilities are connected to issue various contracts and sub-contracts in the structure of an organization.

In projects and programmes a functional breakdown structure can be used to map the work to be performed to the functional areas within the organization or organizations doing the work. The functional breakdown structure can reflect discipline units, such as mechanical or electrical engineering, accounting, procurement, or testing. Mapping the work from the work breakdown structure into a functional breakdown structure can provide information for activities, such as schedule negotiation, personnel planning, or supplementing budget estimates for the work to be performed.

Mapping to functional areas can enhance communication for the project or programme manager, especially in the area of resource management within areas of functional specialties. Further, if used along with the risk breakdown structure and the work breakdown structure, the project or programme manager should be able to highlight areas of risk resulting from issues of personnel and resource restrictions in functional areas.

Risk breakdown structure is a breakdown of categories or sources of risks. Risks can be identified against each work breakdown element and at the overall project or programme level using the sources defined in the risk breakdown structure.

Each risk should be documented in a risk register under at least one risk breakdown structure category or source to support detailed analysis, management decisions, and lessons learned. As risks are identified, they should be considered for cost and schedule impact, and treatment actions should be planned.

Figure 9 shows an example of correlations between a risk breakdown structure and a work breakdown structure. The example focuses on the relationship between project or programme risks and Level 3 project or programme work breakdown structure.

Categories of project risks such as budget, schedule and supply chain are related to the project, programme and portfolio management office Level 3 in the project organization structure. Whereas the scope, quality, change management, teams and resources categories of risks fall under the engineering and design work breakdown structure. Correlations with the risk breakdown structure can also be applicable to other levels and sub-levels of the work breakdown structure. There can be many to many relationships between the risk breakdown structure and the work breakdown structure.

Figure 9 —Example of the relationship between risk breakdown structure categories and work breakdown structure

Some of the structures with which the work breakdown structure can be integrated are:

1. cost breakdown structure;
2. schedule;
3. communication breakdown structure;
4. resource breakdown structure;
5. matrix management structure;
6. project or programme or portfolio management office structure.

Integration can be two-dimensional or multi-dimensional, depending upon the needs of the project or programme. When the work breakdown structure and organizational breakdown structure are integrated to assign work to organizations the resulting structure can be known as the control accounts. Control accounts should have one work breakdown structure element and one organization structure. When multifunctional teams are used, the technical team can be aligned with responsible team members assigned from various parts of the performing organization.

NOTE Organizations can be assigned one or more control accounts, but each control account has a unique work breakdown element and identifying code. Figure 10 illustrates a work breakdown structure related to a warehousing system with focus on construction management as level 2. This figure shows the warehousing construction work breakdown structure with construction management, planning, execution, permitting and demobilization as level 3 components. Each of these level 3 components are divided into level 4 components.

1. Outline Structure of a Warehousing System
   1. Engineering
   2. Procurement
   3. Construction
      1. Construction management
         1. Schedule
            1. Milestones
            2. Tracking
         2. Budget
            1. Cost control
            2. Monitoring
         3. Quality
            1. Inspections
            2. Surveys
            3. Monitoring
            4. Field reporting
            5. Contract compliance
         4. Safety
            1. Safety compliance
      2. Planning
         1. Construction documents
         2. Budget
         3. Schedule
         4. Constructability reviews
         5. Other related planning
      3. Execution
         1. Foundation
            1. Excavate
            2. Concrete
         2. Exterior
            1. Framing
            2. Siding
            3. Roofing
            4. Landscaping
         3. Interior
            1. Dry wall
            2. Plumbing
            3. Electrical
            4. Finishes
            5. Heating, ventilation and air conditioning
            6. Miscellaneous
      4. Permitting
      5. Demobilization
         1. Site
         2. Equipment
         3. Clean-up
   4. Commissioning, qualifications, validations
   5. Project closure
   6. Project management office

Figure 10 — Example for an outline structure of a warehousing system

Figure 11 explains the relationship between prime contract work breakdown structure and sub contract work breakdown structure of a new warship class. The figure focus is on propulsion system as the prime contract level 3 work breakdown structure component and for the same as sub-contract as level 1. The sub-contract work breakdown structure further explains details and framework of the propulsion system.

Figure 11 —An example of a work breakdown structure relationship between a prime contractor and a subcontractor

When a portfolio framework is utilized to integrate work strategically across projects and programmes and other work components, the organizational breakdown structure can start at the portfolio level to facilitate organizational integration objectives.

1. ISO 21502:2020, Project, programme and portfolio management — Guidance on project management
2. ISO 21503:2022, Project, programme and portfolio management — Guidance on programme management
3. ISO 21504:2022, Project, programme and portfolio management — Guidance on portfolio management
4. ISO 21505:2017, Project, programme and portfolio management — Guidance on governance
5. ISO 21506:2024, Project, programme and portfolio management — Vocabulary
6. ISO 21508, Earned value management in project and programme management
7. ISO 21512:2024, Project, programme and portfolio management — Earned value management implementation guidance