In Building Information Modeling (BIM), Level of Development (LOD) is a standardized scale that defines the degree of detailing and information contained within the 3D model elements at different stages of a construction project.
LOD serves as a common language to communicate the level of refinement and reliability of model components. It allows model authors to clearly specify the intended accuracy and limitations of their models. Downstream users can then understand the usability and data richness of the models they receive.
There are six established LOD levels:
- LOD 100 - Conceptual: Basic shapes/sizes representing overall design intent, lacking detailed information.
- LOD 200 - Schematic: Approximate sizes, shapes, quantities and locations allowing analysis of design concepts.
- LOD 300 - Detailed: Precise geometric representation with accurate sizes, shapes and object details for construction documentation.
- LOD 350 - Construction: Model elements show fabrication-level detailing and connection specifics for shop drawings.
- LOD 400 - Fabrication: Highly detailed models with assemblies and connections suitable for fabrication and installation.
- LOD 500 - As-Built: The model reflects the actual constructed conditions with operational and maintenance data.
As the LOD increases from 100 to 500, the model elements progressively incorporate more precise geometry, detailed components, and comprehensive data attributes aligned with the project phase requirements.
Specifying and adhering to the appropriate LOD at each stage optimizes modeling efforts, enables effective collaboration among teams, and supports informed decision-making throughout the asset's lifecycle. It prevents misunderstandings by setting clear expectations on model content and reliability.
