Level of Development is the most cited and least understood concept in BIM specification. It appears in nearly every BIM Execution Plan, is written into contracts, and is routinely misapplied in ways that cost projects time and money. The confusion is usually traceable to a single error: treating LOD as a measure of how detailed a model looks rather than how reliable its information is.
This reference sets out what each level actually commits you to and how to specify it in a way that survives contact with a real project.
LOD is about reliability, not resolution
The AIA and the BIMForum LOD Specification define Level of Development as the degree to which an element's geometry and attached information can be relied upon by downstream users. A model element at LOD 200 may look photorealistic and still be approximate. An element at LOD 350 may look plain and be dimensionally binding.
The related term level of detail describes visual richness. The two are independent. A rendering-ready family with beautiful geometry and no reliable dimensional commitment is high detail and low development. Conflating them is how firms end up field-verifying models they were told were construction-ready.
The six levels
LOD 100 — Conceptual
The element is represented symbolically or by a generic mass. Area, height, volume, location, and orientation may be inferred, but no dimension is committed. Typical use: massing studies, early cost-per-square-foot benchmarking, zoning and envelope tests.
What you can rely on: overall footprint and gross area. What you cannot: anything about assembly, thickness, or system selection.
LOD 200 — Approximate geometry
The element is a generic placeholder with approximate quantities, size, shape, location, and orientation. Non-geometric information may be attached as generic descriptions. Typical use: schematic design, early system sizing, comparative option analysis.
This is the level at which most design-stage coordination happens, and it is the level most often over-trusted. Quantities extracted here should be treated as indicative, with an appropriate contingency.
LOD 300 — Specific assemblies
The element is modeled as a specific system, object, or assembly with accurate quantity, size, shape, location, and orientation, measured directly from the model. This is the workhorse level for design development and construction documentation.
Critically, LOD 300 does not include how elements connect or how they are installed. A duct is correctly sized and located; hangers, insulation clearance, and the actual routing tolerance are not committed.
LOD 350 — Interfaces and supports
LOD 350 exists because LOD 300 proved insufficient for trade coordination. It adds the interfaces between systems: supports, connections, hangers, sleeves, penetrations, and the parts of an assembly required to coordinate with adjacent trades.
For most multi-trade coordination scopes, LOD 350 is the correct specification. Requesting LOD 300 and expecting clash-free installation coordination is a common and expensive mismatch.
LOD 400 — Fabrication and assembly
The element is modeled with sufficient detail and accuracy for fabrication, assembly, and installation. Steel connections are fully detailed, rebar is placed with actual bar marks and bends, ductwork reflects the fabricator's actual sections and fittings.
LOD 400 is trade-contractor territory. Design firms should generally not commit to producing it, because it embeds means and methods, which carries liability implications.
LOD 500 — Verified as-built
The element represents a field-verified condition in terms of size, shape, location, quantity, and orientation. LOD 500 is not simply "the model at the end of the project"; it requires actual verification, typically by laser scan or surveyed control.
Attaching asset data — serial numbers, warranty dates, maintenance intervals — is usually associated with LOD 500 handover, though information handover is more precisely governed by COBie or an equivalent asset information requirement.
Specify LOD by element, not by project
The single most useful practice in LOD specification is refusing to state one number for the whole model. Real projects need different reliability in different places.
A realistic specification for a construction documentation package might read:
| Element | LOD |
|---|---|
| Site and topography | 200 |
| Structural frame | 350 |
| Structural connections | 300 (400 by fabricator) |
| Exterior enclosure | 350 |
| Interior partitions | 300 |
| Ceilings and soffits | 350 |
| HVAC distribution | 350 |
| Plumbing risers and mains | 350 |
| Electrical distribution equipment | 300 |
| Cable tray and conduit above 1" | 350 |
| Furniture and equipment | 200 |
This table, attached to the BEP with an element breakdown structure such as Uniformat, removes almost all downstream ambiguity. It also protects the modeling team from scope creep, because anything requested above the stated level is a variation.
Who is responsible at each level
LOD specification should always name the Model Element Author — the party responsible for developing that element to that level at that project stage. The same element commonly changes authorship: the engineer authors the structural frame to LOD 350, and the fabricator takes it to LOD 400. Without an authorship column, the LOD table is a wish list.
Common specification errors
Requesting LOD 400 across the design model. This asks the design team to commit to means and methods they do not control and cannot warrant.
Assuming LOD 500 arrives automatically. As-built verification is a separate scope with a real cost. It does not happen because the project finished.
Using LOD to price without an element table. "LOD 300 model" as a scope line is unpriceable with any accuracy, which is why bids against it vary so widely.
Ignoring LOD progression. Elements advance at different rates. A single LOD stated at a single milestone rarely reflects how the model actually matures.
How LOD interacts with fee and programme
LOD is a commercial instrument as much as a technical one, and firms that treat it only technically leave money on the table or absorb scope silently.
The modeling effort between adjacent levels is not linear. Moving an element from LOD 200 to LOD 300 is a significant step, because the generic placeholder becomes a specific assembly with real dimensions. Moving from LOD 300 to LOD 350 is another substantial step for MEP and structure, since every interface, support and penetration must be modeled. LOD 350 to LOD 400 is the largest step of all, and it is properly a trade contractor's scope.
Practical consequences:
- Price by element, not by model. A fee based on "LOD 350 model" is unbounded. A fee based on an element table with levels stated is defensible on both sides.
- Treat level increases as variations. When a client asks mid-stage for supports and hangers to be modeled that were specified at LOD 300, that is additional scope, and the element table is the evidence.
- Stage the progression. Elements should advance at the stage they are needed, not uniformly. Modeling the structural frame to LOD 350 at concept stage wastes effort that a design change will discard.
A workable specification method
The method that produces the least friction on real projects has four steps.
1. Start from the model uses. List what the model must actually support — coordination, quantity extraction, energy analysis, fabrication, handover data. Each use implies a minimum reliability for particular elements, and nothing else needs to be raised.
2. Build the element table from a recognised breakdown. Uniformat or an equivalent, so nothing is omitted by oversight and so the table maps cleanly to cost structures.
3. Assign level, author and stage per element. Three columns, filled for every row. Blank cells are exactly where disputes originate.
4. Attach it to the BEP and revisit it at each gate. An LOD table written once at project start and never reviewed will diverge from what the project actually needs within a stage.
Firms that adopt this find that most arguments about model adequacy disappear, because the question "was this element delivered as specified" becomes answerable by looking at a table rather than by negotiation.
Frequently asked questions
Is LOD the same as the UK's information levels? No. ISO 19650 uses Level of Information Need, which covers geometric information, alphanumeric information, and documentation together. It is a broader and, in some respects, more useful framing, but the two are frequently mapped to each other in practice.
Does higher LOD always mean better? No. Modeling beyond project need consumes budget, slows iteration, and creates a false impression of certainty. The correct LOD is the lowest one that supports the decisions being made.
How do I audit delivered LOD? Spot-check dimensions against the model, verify that required parameters are populated and not defaulted, and confirm interfaces exist where LOD 350 was specified. Visual inspection alone will not detect the difference between LOD 200 and LOD 300.
Related reading: BIM Outsourcing: A Practical Guide for AEC Firms · Structural Steel Detailing: From Design Model to Fabrication File
Vantage CAD Services delivers BIM models specified by element and level of development, working within your template and BIM Execution Plan. Contact info@vantagecadservices.com or +1 (512) 543-0831.