Monday, May 13, 2013

LOD Specification is Here!

After two years of dedication and hard work, the first draft of the BIM Level of Development (LOD) Specification is finally available for public comment. The work group responsible for this important document is a joint task force consisting of members of the AIA and the AGC of America’s BIMForum.

Cam_LOD200-100 Cam_LOD200 Cam_LOD300

You might be asking, ‘what is an LOD Specification and why do I need one?’ The AIA’s digital practice documents defines 5 fundamental levels of model development, but offers only general definitions of what each level means. I offered some explanation of these in an older blog post.

This new document offers more detailed definitions of how model authors must create virtual components in order to satisfy the requisite reliability. Building upon the AIA’s original LOD definitions, the LOD Specification can be seen as a companion document – much the same way as a dictionary can be a companion to both an author and a reader.

The public comment period will be completed by early June 2013, but the work group will continue to revise the LOD Specification and publish it on an annual basis. Go to to download your free copy today. I’ll provide more feedback and commentary in future posts.


  1. James, I was impressed by how much space in the document which they devoted to MEP objects. Lets face it, many architects are going to want basic objects on that end of things to insert into designs. I've listen intently to what the FM community have been saying about LOD in the past number of years, and I would say the FM guys in terms of MEP objects, are leaning towards the highest level of details as shown in the LOD spec - not for the nice bevelled corners and shiny reflective materials -but for basic stuff like access zones.

    If I was to have a criticism of this document, I would maybe hope that access zones could be incorporated into less detailed LOD objects, and they would arise from earliest clash detection done by contractors getting into the BIM process with designers earlier and earlier. Just a thought.

    I know you are no stranger to IPD and densely packed service zones, so you will be well aware of the above.

  2. For those who read French, here is a good explanation of BIM - IFC :, and what the French call the digital model/sketchup/mockup (maquette numérique).