In this post, The CAD Room explores 3D, 4D, 5D and 6D BIM and shows how adding extra information can make for better buildings, thanks to more timely decisions being made.

What is BIM?

Building information modelling (BIM) is the name given to the process of creating and managing information throughout the lifecycle of a construction project. A coordinated digital description of the built asset is created as part of this process, using the appropriate technology. This digital description usually contains a combination of information-rich 3D models and associated structured data such as execution and handover information.

The BIM process and associated data structures are defined in the ISP 19650 and 12006 series of international standards.

What are BIM dimensions?

BIM dimensions evolved from a need to be able to differentiate between modelling geometry in two or three dimensions. This is part of the modelling evolution from drawing boards, to 2D CAD systems to 3D modelling packages.

Adding further aspects to these models can help project teams better understand what information it is they are setting out to model.


2D BIM is a geometric model that constitutes an X and Y axis that is associated with further information digitally. Early 2D CAD systems were used to develop plans and sections more accurately and quickly than on a manual drawing board.

More advanced modelling tools now allow constraints, concepts and parameters to be attached to 2D models, but most people in the industry would not consider a 2D model to be part of BIM.


3D BIM is a geometric model that constitutes an X, Y and Z axis that is associated with further information. 3D modelling tools became a huge success thanks to an improvement in accuracy and efficiency on 2D models, and the reduction in risk of errors potentially occurring on projects.

Also, when specific information is added to or linked to 3D models, further benefits can be seen.


4D BIM comes into play when scheduling information is added to model construction sequences as it allows the project team to be able to better visualise how the construction will be sequenced – which is vital from a contractor point of view.

4D BIM was a huge step forward for the construction industry as it not only demonstrated collaboration between the design and construction teams but also allowed the sharing of 3D models.


5D BIM is a term that is generally used when cost information is added to a model and it is advised that these requirements are clearly set out when a 5D model is discussed. Some things you may want to consider are:

  • Is the team expected to provide operational or capital costs?
  • Are these costs expected to be as-built or pre-tender costs?
  • Who is responsible for adding cost information?
  • What method of measurement is to be used?


6D BIM is the addition of facility management to the information set, but there is not much industry consensus on this yet and some people say this isn’t a ‘dimension’ at all.


7D BIM is the addition of sustainability information to the data set, although again it is better to clearly define the specific information required such as data types, rules, scope and units of measure.


This BIM dimension is associated with the addition of health and safety information to the information set.

Using dimensions to define information requirements for BIM can be helpful when starting conversations with our clients to extract their requirements or understand the potential deliverables.

If you want to harness the power of BIM on your next project, and want a BIM outsourcing partner who can help you do that – please contact the team at The CAD Room today. You can call us on 0161 427 0348 or email us at office@thecadroom if you prefer.