What Is LOD 400 BIM?

Level of Development, or LOD, describes how much geometric and non-geometric information a model element contains, and by extension, what decisions can reliably be made from it. It's a scale, not a single standard, and different projects define it slightly differently — but the general progression is consistent across the industry.

LOD 200 elements are generalized systems or assemblies with approximate size, shape, and location — useful for early design coordination, not construction. LOD 300 elements are modeled with specific size, shape, quantity, and location, accurate enough for general coordination and quantity takeoff. LOD 350 adds the interface information needed to coordinate with other building systems, such as connection points between structural and MEP elements.

LOD 400 is modeled with the detail needed for fabrication — exact connection geometry, materials, and assembly information, the level a shop can build directly from. That's the level structural steel detailing models are typically built to.

Knowing which LOD a deliverable needs to hit — and confirming it in the BIM execution plan before modeling starts — prevents two common problems: over-modeling elements that don't need fabrication-level detail, and under-modeling elements a fabricator later has to redetail from scratch.