BIMForum LOD Spec: What’s Your View?

Last week (22/8/13) The LOD Specification was released in its final draft by the BIMForum and it is a very worthy guide to consider. It was written under agreement with the American Institute of Architects and it looks at the detail of what it is that you’re designing and what it can be used for.

“We want everyone to have the same understanding about how much information should go into each element of a building model, and for what uses those models are suitable,” – Dmitri Alferieff, director of the BIMForum.

What I find interesting about this guide is that:

  • It uses descriptions and images so that designers can define the model uses and limitations to downstream users.
  • For contractors it introduces an additional LOD – 350 as well as the basic LOD definitions developed by the AIA for the AIA G202-2013 Building Information Modeling Protocol Form.
  • The information is organised by CSI Uniformat 2010 codes. If this guide successfully gains traction around the globe then it is logical that Uniformat will become the preeminent international classification system.

The intention of ‘LOD 350’ is to enable elements to be sufficiently developed to allow proper coordination of disciplines (e.g. clash detection/avoidance, layout, etc…). This concept resonated with me because it provides guidance to contractors and subcontractors on the improvements that are required to develop a “for tender or bid” model into a ‘for construction” model. This concept can be applied to any procurement method even hard dollar (design – bid – build) contracts by adopting the “Plan to Build” model which you can see below:

From my 5D perspective BIMForum have pretty much gotten it right, except I would have preferred to have seen rebar contained within LOD 350 rather than LOD 400 because reinforcement supply costs often blow out by large margins and this isn’t evident until the last bar is delivered. Rebar that is modeled at the outset of construction is very easy to track financially.