IFC file: all you need to know

IFC file: all you need to know

What is an IFC file? What is an IFC file structure? How to open an IFC file? Frequently asked questions with answers in the whitepaper for download with the help of free software

The IFC file has been a real revolution in the AEC industry, as it represents a common language for all operators involved in the entire building’s life cycle.

But what is an IFC file? What is it used for? How is it structured? In this focus article we will address these questions that can result handy for your everyday work.

You can also download the in-depth White Paper that covers the main aspects relating to this topic.

logo of the IFC format

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What is an IFC file

In order to fully answer the question “what is an IFC file?”, it is necessary to make a brief introduction to BIM.

BIM (Building Information Modelling) is an operational methodology that allows cooperation between the players involved during the various phases of a building’s life cycle, in order to import, export, update or modify model information.

The IFC file is an open, non-proprietary file format, international standard ISO 16739, and can be used to exchange and share data, during design, construction, operation and maintenance phases, between all the figures and the various applications developed by different software houses without the need for them to support native (proprietary) files.

What is an IFC file

Interoperability in a closed and open system

On the other hand, the IFC is not only an exchange format, but a schema, i.e. an organised data structucture according to precise rules: the IFC schema can be thought of as a ‘filing system’ for organising and transporting digital data.

To know more about this topic, read the article “IFC format and Open BIM, all you need to know“.

IFC file structure

Designed by buildingSMART International to support interoperability between individual applications operating in the AEC sector, the IFC format allows the production of files that include:

  • geometric information of the various entities of ‘simple’ building components (such as walls, doors, floors, etc.) and all associated data;
  • alphanumeric information (properties, quantities, classification, etc.) specifying their parameters, physical properties, construction information, maintenance information, etc.

The logic of the IFC is based on 3 fundamental concepts, which represent the structure itself and define:

  • IfcObjectDefinition: entities (objects)
  • IfcRelationship: entity relationships
  • IfcPropertyDefinition: properties associated to entities.



IFC Data schema composition

A BIM model is a model consisting of specific parametric entities that have relationships with each other and whose technical characteristics are described through properties.

To know more obout this topic, take a look at the below articles:

IFC file format

The IFC file can be encoded in different formats, each one with its own characteristics.

The official formats published on the buildingSmart International website are:

  • .ifc: default file format based on the ISO STEP Physical Format (SPF) standard
  • .ifc-xml: encoding based on the XML language
  • .ifc-zip: a compressed archive of one of these formats
  • .ttl: encoding based on the ifcOWL language
  • .rdf: encoding based on the ifcOWL language

According to buildingSMART International, the IFC format is the main tool for Open BIM implementation.

Model View Definition and BIM

MVDs are subsets of the IFC schema as defined by buildingSMART International that group together certain information useful for specific workflows or uses.

These “filtered views” are very useful as they make the data exchange process simpler and avoid sharing unnecessary or redundant notions, following standardised procedures.

The following image shows the idea of the completeness of the IFC schema and how an MVD specification is able to streamline it according to certain information.


IFC schema and MVD

As it can be seen from the image above, the MVD is a filtered view that takes in some or all of the information from the entire schema.

Therefore, an MVD function does not depend on the many software packages on the market, but on the information to be shared.

This is the result of a specific need, i.e. to transfer the information necessary for a specific situation, facilitating the exchange between the software available at an international level.

Read the article “Model View Definition (MVD) and BIM data exchange” to know more about this topic.

Classification systems in the construction sector

A classification system is the grouping and coding method that allows you to organise entities.

There are different classification systems, with different ways of categorising them, such as:

  • Omniclass
  • Uniclass
  • Uniformat
  • Masterformat
  • etc.

Here are few tips that might be useful to most AEC professionals regarding how to open an IFC file and how to convert a DWG file into an IFC file.

How to open an IFC file

If you need to open an IFC model, or even if you simply want to view it in 3D or modify its geometry or properties, I recommend you to use a very easy-to-use free software, and even  certified by buildingSMART International: usBIM.viewer+.

To open, view and edit an IFC file using the usBIM.viewer+ software simply:

  • download usBIM.viewer+for free
  • open the software and click on Create document from IFC
  • select the file to open
  • view the 3D model, the entities and properties.

How to convert a DWG into IFC file

If you are working on a DWG project or 3D block and you need to convert it in IFC using a simple and reliable tool, follow the steps below.

  1. Download and install immediately usBIM.viewer+ for free
  2. Choose the option Create document from 3D file
  3. Select the 3D model to convert
  4. From the toolbar, click on Export IFC file.

Having to convert files from DWG, SKP, OBJ, 3DS format to IFC format is a frequent need today and for which it will be necessary to use a specific software.

Whitepaper for download

The below Whitepaper (document that examines timely technical issues) comes with a collection of various articles relating to the IFC and previously published in our BibLus blog posts.

To find out more about the IFC file format, download immediately the ACCA software whitepaper.