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IFC objects OmniClass classification

OmniClass classification for IFC objects

OmniClass is a classification system for the construction industry based on a BIM approach for organising reports and object libraries. Find out how to classify IFC model entities with the OmniClass system

Do you need to classify the entities of an IFC project or to read a classification associated with the entities present in an IFC file? This post is all about OmniClass classification system.

Follow my tips and try to classify and add information to the entities in a 3D model with an advanced IFC editor.

OmniClass classification for IFC objects

OmniClass classification of IFC objects with usBIM.editor

What is the OmniClass classification system?

OmniClass is a system adopted in North America (according to ISO 12006-2 international standard) and used for organizing and retrieving of information throughout the full facility life cycle, from conception to demolition. The system adapts to all levels of detail of a work: be it industrial, commercial or residential, from materials to construction systems.

IFC objects OmniClass classification


Omniclass tables

OmniClass consists of 15 tables, each of which deals with different construction information.

Each table can be used individually or in combination with others to classify more complex information, while the system can always be updated with the addition of new elements.

The tables organization draws its definitions from ISO 12006-2:

  • tables 11 to 22 describe construction results
  • tables 23-33-34-35 and partly 36 and 42 classify information on construction resources
  • tables 31 and 32 organize the construction processes and phases throughout the construction life cycle.

The chart below shows some examples to better understand how to classify an entity with the OmniClass system.

Table cod.
Number cod.
Description Example
Table 11 11-00 00 00 Entities of the construction system (classified by function) Private residences, hotels, congress centres, bus stations, motorways, etc.
Table 12 12-00 00 00 Entities of the construction system (classified by shape) Apartment houses, skyscrapers, bridges, landing platforms, etc.
Table 13 13-00 00 00 Spaces (classified by function) Bedrooms, offices, gyms, motorways, etc.
Table 14 14-00 00 00 Spaces (classified by shape) Courtyards, patios, recesses, interspaces, etc.
Table 21 21-00 00 00 Elements (including designed elements) Exterior walls, stairs, roof, furniture, etc.
Table 22 22-00 00 00 Activity results Metal carpentry, concrete casting, ceramic coating, lighting system, plumbing pipes, railroad tracks, etc
Table 23 23-00 00 00 Products Concrete, bricks, mortar, windows, boilers, manholes, etc.
Table 31 31-00 00 00 Phases Defining the project concept, preparing documents to obtain a building permit, the construction phase, disposing of construction waste, etc.
Table 32 32-00 00 00 Services Planning, the offer, construction estimating, site surveying, etc.
Table 33 33-00 00 00 Disciplines Architecture, construction company, structural engineering, administration, etc.
Table 34 34-00 00 00 Organizational roles Site engineer, designer, plant designer, BIM manager, real estate agent, process manager, etc.
Table 35 35-00 00 00 Tools Scaffolding, work tools, design and calculation software, construction site fencing, vehicles, formwork, etc.
Table 36 36-00 00 00 Informations Project files, building regulations, property titles, maintenance and management manuals, site journal, etc.
Table 41 33-00 00 00 Materials Steel, wood, concrete, plastic, etc.
Table 49 49-00 00 00 Properties Colour, area, length, transmittance values, fire resistance, etc.

Each information is classified and detected by a six-digit identification code which refers to the table.

The first two digits indicate the reference table while the subsequent pairs of numbers identify the typology for each level.

For example, a foundation wall is identified by the code 21-01 10 10 10, corresponding to:

  • table 21 – Elements
  • level 1 – Substructures
  • level 2 – Foundations
  • level 3 – Standard foundations
  • level 4 – Foundation wall.

In this way, by reading the code and the classification system adopted, it is possible to uniquely identify an entity and retrieve more information about it.

OmniClass classification for IFC objects

OmniClass classification system

How to classify IFC entities with usBIM

We’ll now show you how to classify any entity (e.g. roof, wall, window, etc.) of an IFC model. You can try yourself to classify the elements of the IFC file using an online IFC editor.

Here are the steps to follow to classify IFC entities, according to the OmniClass classification system:

    • log in to usBIM;
    • open the IFC file;
    • select the usBIM.editor application (top left menu);
    • click on Edit classification;
    • select a model entity;
    • add a new classification;
    • fill in the editable fields;
    • associate a standard classification system;
    • choose the classification type;
    • choose subcategories to associate with the selected entity;
    • view the changes in the properties toolbox.

This is how you can classify an entity or group of entities according to the OmniClass system.

To verify the entity classification in an IFC file you can use again a free online BIM viewer.

Follow these simple steps:

  • open the file with usBIM
  • select an entity (for example a door, a wall, a slab, etc.)
  • read the information relating to the classification on the Properties toolbox on the right-hand side:
    • IfcClassificationReference will report the code;
    • IfcClassification will specify the information relating to the type of classification system adopted (in this case OmniClass).

Remember that with usBIM.editor you can classify objects according to the main classification systems:

  • MasterFormat
  • NatSpec
  • NBS Create
  • OmniClass
  • UniClass (versione 2)
  • UniClass 2015
  • UniFormat.