BIM LOD Levels Explained: One Steel Beam, From LOD 100 to LOD 500

By Sonali Dhopte, Chief Strategy Officer, Excelize. Last updated October 2026.

The latest edition of the BIMForum Level of Development Specification, the reference many U.S. teams use for BIM LOD levels, is dated December 30, 2025. It defines six levels, LOD 100, 200, 300, 350, 400, and 500, and U.S. teams use them every day in BIM execution plans, scopes of work, and coordination meetings. Yet “LOD 350” still means different things to different people on the same project.

The confusion usually comes from treating LOD as a property of the whole model, or as a measure of how detailed it looks. It’s neither. LOD describes how far each element has been thought through, and so how much someone else can rely on it.

So instead of reciting six definitions, this guide follows one element, a steel beam on the third floor of a U.S. office building, through every level. At each step you’ll see what’s modeled, what you can rely on, and who usually owns it. Then we’ll cover how to specify BIM LOD levels in a U.S. project, and the mistakes that cause most LOD disputes.

What does LOD mean in BIM?

LOD stands for Level of Development. The 2025 BIMForum LOD Specification draws the key distinction: “Level of Detail is essentially how much detail is included” in an element, while “Level of Development is the degree to which the element’s geometry has been thought through.” A beam can look detailed and still be unreliable, or look simple and be exactly right.

BIMForum says the specification helps model authors communicate “what their models can be relied on for,” and helps downstream users understand “the usability and the limitations of models they are receiving.” It’s organized by CSI UniFormat 2010 and OmniClass, element by element.

BIM LOD levels explained with one steel beam

LOD 100: The beam is a concept

What’s modeled: Nothing beam-shaped, necessarily. The BIMForum definition says the element “may be graphically represented… with a symbol or other generic representation.” At this stage, the structure might be a mass or a grid with an assumed floor depth.

What you can rely on: That there will be a structural floor system here. Not its size, depth, or position.

Who usually owns it: The architect or structural engineer, during concept and early schematic design.

LOD 200: A generic beam in roughly the right place

What’s modeled: A beam “generically and graphically represented” with “approximate quantity, size, shape, location,” in BIMForum’s words. Think of a placeholder W-shape at an assumed depth along the gridline.

What you can rely on: Rough counts and an early sense of floor depth for planning. Not exact dimensions.

Who usually owns it: The structural engineer, through schematic design and design development.

LOD 300: A specific beam you can measure

What’s modeled: The designed member, such that its “quantity, size, shape, location, and orientation can be measured” directly from the model. The beam now has its real size and its real position.

What you can rely on: Dimensions and location for design coordination and construction documents.

Who usually owns it: The structural engineer of record, by construction documents.

LOD 350: The beam and everything it touches

What’s modeled: The beam is “sufficiently developed to support construction-level coordination.” In practice, that means the parts that affect other trades are modeled too: connections, supports, and the interfaces with other building systems, such as the duct that has to pass beneath it or the sprinkler main hung from it.

What you can rely on: Coordination with other trades. This is the level at which clash detection between structure and MEPF becomes meaningful.

Who usually owns it: Often the construction team, through the GC’s coordination process, with input from the steel detailer and MEPF trades.

LOD 400: The beam as the fabricator will build it

What’s modeled: The beam “with detail sufficient for fabrication, assembly, and installation.” Bolt patterns, plates, copes, and holes for penetrations are all defined, usually in a detailing tool such as Tekla.

What you can rely on: Fabrication and erection. Shop drawings and CNC data come from this model.

Who usually owns it: The steel fabricator or detailer, with review by the engineer of record.

LOD 500: The beam as it actually exists

What’s modeled: The BIMForum specification defines LOD 500 as a “graphic representation of an existing or as-constructed condition developed through observation, field verification, or interpolation.” For our beam, that might mean its position checked against a laser scan after erection, or its as-built condition on a future renovation.

What you can rely on: That the geometry reflects what’s really there, to whatever accuracy the verification method achieved.

An important point: BIMForum states that “LOD 500 does not indicate a higher level than LOD 400, rather it indicates that the element’s geometry is determined through observation.” It’s a different kind of reliability, not one more step up the ladder.

What can you rely on at each BIM LOD level?

What is the difference between LOD 300, LOD 350, and LOD 400?

This is where most LOD disputes happen on U.S. projects.

• LOD 300 is about the element itself. Its size, shape, and location are designed and measurable. It’s typical for construction documents.
• LOD 350 adds the element’s relationships. Supports, connections, and interfaces with other systems are modeled so trades can coordinate. It’s typical for GC-led coordination.
• LOD 400 adds how it gets made. Fabrication and installation detail is modeled. It’s typical for shop drawings and prefabrication.

A simple test: if the question is “where is it?”, you need LOD 300. If it’s “what does it hit?”, you need LOD 350. If it’s “how do we build it?”, you need LOD 400.

LOD vs. Level of Detail vs. LOA: three terms that get mixed up

• LOD (Level of Development): How far an element’s geometry and information have been thought through, as defined by BIMForum.
• Level of Detail: How much graphic detail is shown. Useful, but not a measure of reliability.
• LOA (Level of Accuracy): How closely measured geometry matches the real building, defined by the USIBD Level of Accuracy specification. It matters most for LOD 500 and existing-conditions work. Our scan to BIM accuracy guide explains it.

Some contracts also refer to the level of information carried with an element, such as manufacturer or model number. Write down which properties you need instead of relying on a label.

How do U.S. teams specify LOD in a BIM execution plan or contract?

LOD works when it’s written down element by element, not as one number for the whole model.

1. Agree on the definitions: Most U.S. teams reference the BIMForum LOD Specification for element definitions.
2. Build a Model Element Table: List each element group, the LOD required at each milestone, and who’s responsible. Under AIA’s 2022 BIM documents, the G203-2022 BIM Execution Plan can include a Model Element Table for this purpose. Our guide to BIM modeling guidelines for architecture firms covers what changed when AIA’s 2013 documents, including G202-2013, were replaced.
3. Tie LOD to model uses: State what the model will be used for at each milestone, such as coordination, takeoff, or fabrication, so the LOD has a purpose.
4. Name the author: Each element has one model element author at each stage. That’s who the LOD applies to.
5. Check it: Review a sample of elements at each milestone against the agreed definitions.

Five LOD mistakes we see on U.S. projects

• “The model is LOD 350”: Models don’t have one LOD. Elements do, and they develop at different rates.
• Treating LOD 500 as “more than 400”: It’s field-verified, not more detailed.
• Judging LOD by appearance: A detailed-looking family can sit in the wrong place. Check what’s been thought through, not what’s been drawn.
• No author named: If nobody owns the element at a milestone, nobody is accountable for its LOD.
• Asking for LOD 400 from the design team: Fabrication-level detail usually belongs to the trades, not the architect or engineer of record.

How Excelize models and coordinates to your LOD targets

We set LOD targets stage by stage in the BIM Execution Plan before modeling starts, then build to them:

• Design phases: Federated models are built to the LOD each stage requires, typically LOD 200 through design development, LOD 350 for construction document extraction, and LOD 400 where fabrication-ready output is needed.
• Coordination for GCs: Multi-trade coordination typically runs at LOD 350, and up to LOD 400 where fabrication-level detail is required.
• MEPF trades: Mechanical, electrical, plumbing, and fire protection coordinated to LOD 350 to 400 on congested projects such as hospitals and labs.
• Existing conditions: As-built models from LOD 200 to 500 from your scan data, checked against the point cloud to a stated tolerance, with USIBD levels of accuracy where specified.
• Checked, not assumed: Discipline-lead sign-off happens at each checkpoint, and the person approving the work isn’t the person who built it.

Explore our BIM coordination and clash detection services or see how we support general contractors on LOD 350 coordination.

BIM LOD levels FAQ