LOD Spec 2023 Cover

2023 Level of Development (LOD) Specification

The BIMForum announces the publication of the 2023 Level of Development (LOD) Specification.

The BIMForum had created the first version of the LOD Specification in 2013. The current edition marks the 10 year anniversary of the document. In the past 10 years the BIMForum LOD specification has helped countless projects and practitioners defining scope, qualities and expectations of models that are created and managed on construction projects. Eliminating unnecessary room for interpretation and vagueness out of the model creation process allows practitioners to create models more efficiently, but more importantly rely on models and work products created by others. The BIMForum LOD Specification therefore is an integral part in enabling and driving efficiencies into collaborative processes.

The current LOD Specification has received a major update relative to its previous versions. This update is based on user feedback and internal review efforts to enhance the usability and utility of the document.

The major thrust of the update is to resolve conflicts and improve consistency and readability in the logic and format of the text and graphics. Very few changes were made in the actual requirements in
the Specification’s LOD interpretations, and in most cases where changes were made requirements were relaxed somewhat. Several
improvements have been made globally:

  • Elimination of nebulous terms. E.g., use of the term “major openings” has been replaced by a defined size. This size can
    be modified through the use of the Notes function in Part II.
  • Simplification. An example of this is the Interior Finishes section. In looking at the section as a whole it was realized that the
    modeling needs were dictated by the thickness of the finish rather than the material. Thus requirements based on thickness
    are defined for “C20 Interior Finishes”, and these requirements apply to all children of that heading.
  • Defined Terms. This section has been added to succinctly define terms that have specialized meaning in this Spec. The
    defined terms are in boldface where they appear in the LOD narrative descriptions.
  • LOD Requirements. In the narrative descriptions of LOD requirements only items required to be included are listed. No
    reference is made to items that are not required and no items have been listed as prohibited.
  • Narrative Descriptions. These have been organized into lists of specific required items to facilitate use of the Spec as a
  • Non-geometric information. On the principle that any number of non-geometric attributes can be attached to a model
    element of any LOD, non-geometric information is not addressed in Part I.
  • Duplicated Content. The Spec was scrubbed for duplicated content – where found it was deleted or replaced with cross references

The 2023 LOD Specification is now available for public comment until 2024-01-31 (due to various requests we have chanted the end date from 2024-01-15 to 2024-01-31).

The document is posted here: Level of Development (LOD) Specification – BIM Forum

Review comments can be posted here: https://form.jotform.com/233625210758051

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