Hi everyone,
I wanted to open a discussion about something I’ve encountered repeatedly in the BIM field, but which seems to spark a lot of debate: the concept of Level of Detail (LOD).
I recently came across a very insightful article on this topic, published by ENGINYRING:
Understanding Level of Detail (LOD) in Architectural 2D Drawings and 3D Models.
Much of what follows is inspired by or directly references that write-up.
What Is LOD in BIM, and Why Is It So Contentious?
The notion of LOD is everywhere in BIM workflows, project requirements, and even client requests. People toss around terms like LOD 100, LOD 200, LOD 300, and so on, as if everyone agrees on exactly what they mean. But, as the ENGINYRING article points out, “Level of Detail” is a surprisingly flexible term, and its meaning often shifts based on context, region, or even individual project teams.
This ambiguity often leads to mismatched expectations between architects, engineers, clients, and contractors. For example, a client might expect that a “LOD 300” model means everything is fully coordinated, clash-free, and ready for fabrication. Meanwhile, the design team may see LOD 300 as just the level at which systems are spatially coordinated, but not yet constructible.Understanding Level of Detail (LOD) in Architectural 2D Drawings and 3D Models wrote: The term LOD—Level of Detail, sometimes called Level of Development—originated as a way to communicate how much information is contained within a drawing or model at a specific point in a project. But it’s not just about geometry or how “realistic” something looks; it’s also about the reliability and intent of the information. Is this wall a concept, a design-ready object, or a fully specified, ready-to-build assembly?
What Do the LOD Numbers Actually Mean?
According to the ENGINYRING blog (which references the AIA and BIMForum standards), the main LOD stages are:
- LOD 100: Conceptual. Objects are represented by generic placeholders, with only approximate size, shape, and position. Useful for early massing studies, feasibility analysis, and basic spatial planning.
- LOD 200: Approximate geometry. Elements are recognizable as building systems, but details are still schematic. You know where the walls are, but not exactly what they’re made of.
- LOD 300: Precise geometry and location. Objects are defined enough for coordination and construction documentation. This is often where people assume “it’s all figured out,” but it doesn’t always mean all construction-level information is present.
- LOD 350: Enhanced coordination. Model elements include supports, connections, and other parts needed for clear interface between systems. Clash detection and coordination meetings usually happen here.
- LOD 400: Fabrication level. All the data needed for off-site fabrication or direct-to-manufacturing is present. This level is mostly used by contractors and specialty subcontractors.
- LOD 500: As-built. The model is updated to reflect what was actually built in the field, with precise location, size, and other attributes. This is typically used for facilities management.
What’s important to realize, and what the ENGINYRING article emphasizes, is that LOD is about more than just detail for the sake of detail. Each stage has a specific purpose within the project workflow. Adding unnecessary detail too early can actually harm coordination and inflate costs.
Why the Confusion?
If LODs are so well defined, why does confusion persist? As noted in the article, there are several reasons:
- Different stakeholders have different needs. What a structural engineer considers “sufficient detail” is often very different from what an architect, contractor, or owner needs.
- Standards evolve. The AIA and BIMForum guidelines have become more widespread, but they’re not universal. Some firms, especially outside the US, have local or company-specific definitions.
- Project context matters. A high-profile hospital job will have a very different LOD strategy than a small retail renovation. Sometimes, “LOD 350” is enough for a particular scope; other times, LOD 400 is mandatory.
- Miscommunication and assumptions. Many teams assume everyone shares their understanding, but terms get misused, or requirements are left ambiguous.
ENGINYRING Blog wrote: A big part of the LOD problem comes down to communication. All parties need to be clear, early, and specific about what’s expected at each stage—not just for model geometry, but for data and documentation too.
LOD in 2D vs. 3D: Is There a Difference?
One of the most valuable takeaways from the ENGINYRING article is the idea that LOD applies equally to both 2D drawings and 3D models. While BIM is usually associated with 3D models, the core idea behind LOD—what information is available, how trustworthy it is, and what it’s meant to be used for—applies just as much to plans, sections, and elevations.
For example, a 2D floor plan at LOD 200 might show approximate wall layouts and basic room functions, but not every partition, door type, or finish. At LOD 300, the plan would show wall types, door and window sizes, accurate dimensions, and major equipment locations.
In a 3D context, LOD 200 might just have masses for walls and generic windows, while LOD 300 would define each object’s shape and spatial relationship with enough accuracy to coordinate with other disciplines.
The point is, LOD isn’t just about 3D geometry or rendering “nice models.” It’s about project clarity—what the design team can rely on at any given time.
When Is More Detail Too Much?
There’s a temptation, especially with powerful BIM tools, to model everything in detail as soon as possible. But as the article warns, this can backfire:
- Cluttered models become harder to manage, slowing down both software and human workflows.
- Unnecessary information at early stages can create false expectations—clients may think every piece of furniture or every bolt will be accounted for when that’s not actually required.
- Design changes are inevitable, so too much early detail means more work to keep everything coordinated.
As the ENGINYRING blog says: “The goal should be to deliver the right amount of information at the right time—not more, not less.”
How Do You Set LOD on Your Projects?
The article recommends (and I completely agree) that teams should establish clear LOD requirements from the start. This often means using BIM Execution Plans (BEPs) or similar project documents to define, in writing, what each LOD means for every major discipline and deliverable.
Some questions to consider:
- What is the minimum detail needed at each stage for coordination and decision-making?
- How will information be added as the project progresses?
- How are changes and revisions tracked and communicated?
- Who is responsible for each model element at every LOD?
- What standards or guides does your team use to define LOD?
LOD and Data: Beyond Geometry
Another key insight from the ENGINYRING article is that LOD isn’t just about how much geometry is in your model or drawing. It’s also about the quality and completeness of the non-geometric information attached to each element.
For example:
- A door at LOD 200 might have a generic “door” tag, with basic width/height.
- At LOD 300, that door could have hardware specified, a fire rating, and be linked to the project’s door schedule.
- At LOD 400, the door’s manufacturer, serial number, and installation instructions could all be included.
My Takeaway and Some Open Questions
Personally, after reading through the ENGINYRING post and thinking about my own experiences, I believe the industry is getting better at handling LOD, but there’s still a lot of work to do. Clear, project-specific definitions and regular communication between all parties are crucial.
I’m curious:
- How do you and your team interpret the LOD framework? Do you customize the definitions for each client, or use a standard approach?
- Have you run into conflicts or misunderstandings over LOD on projects? How did you resolve them?
- Do you include 2D documentation in your LOD plans, or is it mostly for 3D models?
- Any tools, templates, or reference documents that help clarify LOD in your process?
https://www.enginyring.com/en/blog/understanding-level-of-detail-lod-in-architectural-2d-drawings-and-3d-models
Looking forward to hearing how others handle this—it seems like one of those topics that can always benefit from more real-world insight!
References:
Understanding Level of Detail (LOD) in Architectural 2D Drawings and 3D Models - ENGINYRING