Work Item

A work item is the smallest unit of the project that can be affected by any given constraint or dependency.  The number and granularity is dependent on the size, complexity and number of responsible parties involved in the project.  They are distinct parts of the scope of work and in their sum represent the final result of the project.

The two classes of information that define a work item are “Dimension” and “Property”.  They describe the physical nature of the work item, what it is, how it relates to the work as a whole, how performance will be measured and when execution will occur.  Dimensions are the unique key of the work item.  No two work items share the same key dimensions.  Properties describe quantity, time and status.  A work item would consist of the following dimensions and properties:


  • Phase

  • Constructed Entity

  • Space (By Form or Function)

  • Assembly

  • Work Result

  • Commitment

  • Scope


  • Quantity (Remaining after start)

  • Actual Quantity

  • Duration (Remaining after start)

  • Actual Duration (Calculated)

  • Stage (Calculated)

  • Start Date

  • Completion Date

  • Acceptance Date

  • Actual Start Date

  • Actual Completion Date

  • Actual Acceptance Date

Work Item - Dimensions

Dimensions are represented by a hierarchical tree structure that describe each dimension broadly at the outer most root node with more granularity as you progress deeper in the tree.  Child nodes further decompose its parent into constitute parts. Existing format standards follow this structure and could be used for most of the dimensions or the general contractor could devise a custom value hierarchy to suit its needs.  The key is dimensions are common across all project types and form the basis for how one project is comparable to another.

Each value in a dimension hierarchy is defined by a “Code”, “Title” and “Unit of Measure (UOM)”.  It may also have one or more project specific attributes that qualify the dimension and add detail to comparisons.

When assigned to a work item the dimension value is represented as a tuple, where the key is the dimension type and the value is the dimension value.For example when assigning the concrete formwork dimension value to a work item it would be represented as: Work Result::Concrete Formwork. This notation will be used throughout the remainder of the document when referring to work item dimensions.

Dimension Definitions:

Phase – Segment in time that defines the beginning and completion of the work as a whole or part.  A project can have one or more phases that arise from sequencing the work to satisfy project requirements or owner’s occupancy needs.


  • Working Calendar


  • None

Constructed Entity – Significant definable unit of build environment comprised of interrelated spaces and is characterized by function.  A constructed entity is complete and is viewed separately rather than as a constituent part of a larger built unit.  An office building is a constructed entity but a conference room within the building is classified as a space.  Function is defined by primary occupancy, and not necessarily by all activities that can be accommodated by the constructed entity.  Constructed entities have physical form and location.


  • Working Calendar

  • Physical Location (Address)

  • Quantity of UOM

  • Quality / Grade


  • Appraisal Institute Commercial Data Standards

  • Building Code Occupancy Classifications (IBC, BOCA, UBC…)

  • ISO 12006-2 Table 4.2 Construction Entities

  • ISO 12006-2 Table 4.6 Facilities

  • Uniclass Table D

  • OmniClass – Table 11 Construction Entities – By Function

Assembly – A major component, element, or constructed entity part which in itself or in combination with other parts fulfills a predominating function of the constructed entity.  Assemblies are most often used during early project phases for identifying a project’s physical, operational, or aesthetic characteristics.  Assemblies are considered without regard to a material or technical solutions of the function.  For each assembly there may be several technical solutions capable of accomplishing the function and more than one may be selected for a project.  Predominating functions include but are not limited to, supporting, enclosing, servicing, and equipping a facility.


  • Working Calendar

  • Quantity of UOM

  • Quality / Grade


  • ISO 12006-2 – Table 4.7 Elements

  • ISO 12006-2 – Table 4.8 Designed Elements

  • Uniclass Table G – Elements for Buildings

  • Uniclass Table H – Elements for Civil Engineering Works

  • UniFormat – (CSI/CSC publication 1992, 1998)


  • OmniClass – Table 21 Elements

Space (By Function) – Basic unit of the built environment delineated by physical or abstract boundaries and characterized by function.  A space is a component part of the constructed entity that is marked off from other spaces in some way.  Each space can be defined by its purpose or use so a constructed entities function can be sub-divided into one or more specific sub functions.  Spaces by function allow for a more nuanced cost analysis of a constructed entity.


  • Working Calendar

  • Quantity of UOM


  • Appraisal Institute Commercial Data Standards

  • International Code Council (ICC) space definitions

  • ISO 12006-2 Table 4.5 Spaces

  • Uniclass Table F, Spaces

  • U.S. General Services Administration (GSA) space definitions

  • OmniClass Table 13 – Spaces By Function

Space (By Form) – A part of the constructed entity that is marked off from other spaces by physical or abstract boundaries and characterized by form.  These boundaries determine the physical form of the space which can be three-dimensional such as a room, or a two-dimensional surface such as a walkway.  Spaces by form are used primarily to segment the constructed entity for the purpose of sequencing the work. 


  • Working Calendar

  • Quantity of UOM


  • ISO IS 12006-2 Table 4.4 Spaces

  • Uniclass Table F, Spaces

  • OmniClass Table 14 – Spaces By Form

Work Result – A part of a constructed entity that exists after all required raw materials, human or machine effort, and processes have been provided to achieve a completed condition.  It is characterized by the particular skill or trade involved and the construction resources used.  A work result may pertain to several manufactured products such as exterior insulation and finish system, or to a single product such as chalkboard.  A work result could also involve only labor and equipment which are utilized to achieve the desired result, such as trenching.  Contractual requirements are usually specified by work result describing the intended result but leave the details of the how to the contractor.


  • Working Calendar

  • Quality / Grade


  • ISO 12006-2 Table 4.9 Work Results

  • MasterFormat (CSI/CSC 2004 Edition)

  • Uniclass Table J – Work Sections for Buildings

  • Uniclass Table K – Work Sections for Civil Engineering Works

  • OmniClass – Table 22 Work Results

Commitment - Defines the contractor / contractee relationship - who owns the work and  who is at risk for execution of the work.  Also defines the contractual state of the work items, is the work item something that is proposed?, in-pricing?, committed or contracted?.  Commitment is a hierarchical tree structure that at the outer most level defines who owns the work.  Each successive branch represents the transfer of risk for the actual execution of the work item.  Typical values in this tree would be represented by documents that define the transfer of risk like; bids, contracts and change orders.


  • Contractor organization

  • Contractee organization

  • Status (draft, issued, executed)


  • AIA documents

Scope – This is the only dimension that is not represented by a hierarchical tree structure.  There are only three possible values:

  • Furnish – All Material necessary for the complete installation of the work item delivered to the job site, suitable stored, or suitable stored off site.

  • Install – Unpacking, moving on site and installation of work item complete.

  • Provide – Work item is both furnished and installed as a unit.

Scope allows for the separation of material and installation value.  This would be the case when the organization providing material to the site is directly contracted with the owner or general contractor and the installation is done by a third party.  Also if a subcontractor desires to receive payment for material delivered to the job prior to installation, the work item would be divided into furnish and install work items.  The value would be split accordingly and work items constrained to represent the sequence.

Work Item – Properties

Properties represent the physical and time dimensions of the work item.  They provide a way of quantifying the scope of work so similarly scoped work items can be compared for cost and time with the correct adjustments for volume of work.  The stage of work items determine the overall status of a project.  When all work items are accepted and final paid the project is complete.

  • Units – Quantity of unit of measure for this work item. Unit of measure is defined as an attribute of the Work Result dimension. Units are a way of measuring schedule performance and could be an indicator if work will or will not complete in the anticipated time frame. It could also be used when comparing projects with similar scopes of work for the purpose of cost estimates and budgets.

  • Actual Units – Quantity of units actually installed. For work items that may be paid for on a unit basis this provides a way of documenting how much and when the work was installed.

  • Stage – A categorization of the principle segments of a project. Stages usually are: design, construction documents, procurement, execution, acceptance, and occupancy. Each work item will be in one of these stages during the project life cycle. Stage could be a calculated value derived from start, completion and acceptance constraints.

  • Start Date – Scheduled date the work item is to begin installation.

  • Duration – Estimated quantity of time as defined by the work calendar scheduled for the installation of the work item.

  • Completion Date – Scheduled date when the work item is to be complete and ready for the next work item or items to start.

  • Acceptance Date – Scheduled date when the work item will be 100% complete with no outstanding issues to resolve and is certified for final payment.

  • Actual Start Date – Date work actually commences on the work item.

  • Actual Duration – Actual quantity of time elapsed since the start of the work item to the current date or actual completion date.

  • Remaining Duration – Remaining quantity of time estimated to complete the work item.

  • *Actual Completion Date – Date work item was complete and ready for all successor work items to start.

  • *Actual Acceptance Date – Date the Owner / Architect certifies the work is complete and payment can be made.

* Dates should be substantiated by one or more completion and or acceptance constraint workflows.

 Constraint | Dependency | Time | Summary | Introduction