These regulations also include the properties that a BIM project must meet at different levels. There are in total 5 categories called LOD (Level Of Development): 100, 200, 300 (and 350), 400, 500. These five LODs also indicate the degree of reliability of the information and data included in the 3D model.
What follows is how we see the LODs in the case of the CLT buildings. The concept can be easily extended to all the other structural elements made of timber.
This is the preliminary step of the project and the elements are shown in a generic way and/or with symbols. Any information at this level should be considered approximate.
(CLT panels: not drawn)
The project is a bit more detailed than LOD 100, the building’s shape is quite well defined as well as the position and size of the openings. Quantities and size of the components can be used for a cost analysis. Some extra information can also be linked to the elements.
(CLT panels: drawn. Both thickness and position in the buildup are quite defined. Precision +/-30mm.)
The project is very detailed and accurate: quantities, size, shape, position, properties, etc… of all the elements are defined. The database connected to the 3d model is populated by extra information.
(CLT panels: drawn. Thickness, position in the buildup are defined. All the openings for windows, pipes, etc… are defined. The main penetrations with the structural and non-structural elements are shown. Precision +/- 10mm.)
Fabrication & Assembly (WYDIWYG: What You Draw Is What You Get)
All the model elements are represented with specific information for the production, all the connections between structural elements are designed and eventual clashes are solved. The database connected to the 3d model is fully populated by extra information.
(CLT panels: drawn. Total thickness, position in the buildup, number and thickness of each layer are defined as well as the manufacturer. All the openings for windows, pipes, etc… are defined. The main penetrations with the structural and non-structural elements are solved. Precision +/- 0.5mm.)
The 3d model is exactly as constructed on-site and ready for Facility Management. The database is now populated with a lot of information about the non-structural elements.
(CLT panels: no difference between LOD 400 and LOD 500 unless people change their mind on-site during the assembly.)
Recently, ISO 19650 introduced the LOIN (Level Of Information Need) intending to remove unnecessary information from the model. The LOIN is based on the final use of the 3D model, so there is only useful information.
There will be other articles about this in the future.
In collaboration with: BIM-FARM