A complete, plain-English guide to Levels of Development/Detail & Levels of Information
Building Information Modeling (BIM) only delivers real value when everyone agrees how detailed the model needs to be and what information each element must contain—at each stage of a project. That’s exactly what LOD and LOI solve.
This guide explains what LOD and LOI mean, how different standards use them, the practical differences between the two, and how to specify them on real projects (with examples and a ready-to-copy checklist).
Quick definitions (without the jargon)
- LOD
Depending on the standard you follow, LOD can mean:- Level of Development (BIMForum/US usage): how reliable and constructible an element is (100 → 500).
- Level of Detail/Definition (UK usage): the geometric detail of an element (often paired with LOI).
- LOI – Level of Information
The non-geometric data attached to model elements: specifications, performance data, classifications, costs, serial numbers, maintenance fields, etc.
Think of LOD as “what it looks like and how accurately it’s modeled,” and LOI as “what it knows about itself.”
Why both are necessary
- A highly detailed 3D component with no attributes is pretty but useless for quantities, procurement, or FM.
- A component packed with attributes but poor geometry won’t coordinate or fabricate well.
- Clear LOD/LOI targets prevent scope creep, rework, bloated files, and arguments over “what’s included.”
The LOD scale at a glance (BIMForum/US)
| LOD | What it means (short) | Typical use |
|---|---|---|
| 100 | Conceptual massing, approximate size/position | Feasibility, early options |
| 200 | Generic elements with approximate geometry | Scheme design, studies |
| 300 | Accurate size/shape/location; ready for coordination | Detailed design, approvals |
| 350 | Includes interfaces/clearances and supports | Trade coordination, clash resolution |
| 400 | Fabrication level; includes connections and spools | Shop drawings, prefabrication |
| 500 | As-built verified | Handover, operations & maintenance |
In the UK, you’ll often see LOD (geometry) and LOI (information) used together to describe the “Level of Definition.”
LOI: what information is expected?
LOI is task-driven. Examples of data fields you might require:
- Design: fire rating, U-values, acoustic ratings, flow rates, loads, power.
- Procurement: manufacturer, model, lead times, unit rates, warranty terms.
- Construction: fixings, installation guides, approvals, method statements.
- Handover/FM: serial numbers, spare parts, O&M links, maintenance cycles, location codes, barcodes/QRs.
ISO 19650 encourages describing this as a Level of Information Need—the minimum information required for a decision or delivery at a particular stage.
LOD vs LOI (the difference in one minute)
- LOD (geometry) answers: How accurately is this modeled? Can I coordinate or fabricate from it?
- LOI (data) answers: What do I need to know about it to design, buy, install, operate, or maintain it?
Example – Door
- LOD 300: Exact size, swing, frame profile placed accurately in the wall.
- LOI for design: Fire rating, acoustic class, vision panel spec.
- LOD 400: Manufacturer-specific geometry including hinges/closers.
- LOI for procurement/FM: Model code, finish, hardware set, warranty, serial number, maintenance interval.
Worked examples (copy these patterns)
1) Air Handling Unit (AHU)
- RIBA Stage 3 / LOD 300: Accurate footprint, connections, access zones.
LOI: Duty/standby, airflow (CFM), external static pressure, power, sound. - Pre-construction / LOD 350–400: Lifting points, exact nozzle sizes, maintenance clearances.
LOI: Manufacturer, model, weight, electrical requirements, lead time, cost code. - Handover / LOD 500: Verified geometry/location.
LOI: Serial number, O&M manual link, filter sizes, maintenance plan (e.g., quarterly).
2) Steel Beam
- LOD 300: Correct size/grade, camber, location.
LOI: Section type, grade, fire protection requirement. - LOD 400: Connection plates, bolt sizes, holes, weld symbols.
LOI: Fabricator, coating system, piece mark, pack list reference. - LOD 500: As-built survey alignment.
LOI: Inspection certificate, test results, warranty.
A simple LOD/LOI matrix you can paste into your BEP
| Element Category | Stage | LOD (Geom) | LOI (Data fields – minimum) | Responsible Party | Validation |
|---|---|---|---|---|---|
| Doors (A) | Design | 300 | Size, fire/acoustic rating, material, hardware set ID | Architect | Model check + schedule review |
| Doors (A) | Procure | 350/400 | Manufacturer, model, finish, cost code, lead time | Contractor | Submittal approval |
| Doors (A) | Handover | 500 | Serial no., warranty, O&M link, space code | Contractor/FM | Field verify + COBie check |
| Ducts (M) | Coord. | 350 | System, size, insulation, pressure class | MEP | Clash report pass |
| Ducts (M) | Fab | 400 | Spool/segment IDs, connectors, supports | Fabricator | Shop drawing approval |
Tip: Tie LOI to a classification (Uniclass, OmniClass, MasterFormat) so schedules and exports stay consistent.
How to specify LOD/LOI on your project (5 steps)
- Choose your framework and say it out loud.
In the BEP, state whether you’re using BIMForum LOD (US), Level of Definition (UK LOD+LOI), or an ISO 19650 Level of Information Need approach (recommended for modern contracts). - Define by purpose, not by habit.
For each decision/delivery, define the minimum geometry + data needed. Don’t over-model. - Create an Element Responsibility Matrix.
Who owns what, when, and to what LOD/LOI? Note authoring software and exchange formats (e.g., RVT, NWC, IFC). - Plan validation.
- Geometry: clash tests, clearance rules, model health checks.
- Data: property set rules, required field checks, COBie exports, ID/QR verification.
- Lock it into your CDE workflow.
Use WIP → Shared → Published gates; refuse uploads that fail the LOD/LOI checks.
Common pitfalls (and how to avoid them)
- Mixing definitions: Saying “LOD 400” without stating which framework causes disputes.
Fix: Cite the standard in the BEP and include a one-page legend. - Over-modeling: LOD 400 everywhere bloats files and time.
Fix: Reserve LOD 400 for elements that must be fabricated/prefabbed. - Under-specifying LOI: Great geometry, empty schedules.
Fix: Tie LOI to decisions (tendering, ordering, FM), and make fields mandatory. - Late data: Trying to collect LOI at handover leads to gaps.
Fix: Phase LOI delivery (design, procurement, install, validate). - No QA: Assuming authors will “just know.”
Fix: Automate checks using rule sets; fail uploads that don’t comply.
Where LOD/LOI really pay off
- Cost & time: Reliable quantities and 4D/5D planning reduce change orders.
- Prefabrication: LOD 400 unlocks spooling, modular assemblies, and off-site manufacturing.
- Safety & access: LOD 350+ ensures real clearance zones and maintenance reach.
- FM readiness: Correct LOI at LOD 500 delivers usable digital twins/COBie.
FAQ (30-second answers)
- Is LOD 500 always required?
No. Use it where as-built verification adds value (e.g., FM-critical assets). - Do I need LOD 400 for everything?
No. Target fabricated elements (steel, ducts, MEP skids, façades). - How does ISO 19650 change this?
It promotes Level of Information Need—define exactly what’s needed, avoiding arbitrary “everything at 400.”
Takeaway
- LOD = geometry reliability; LOI = data sufficiency.
- Specify both by stage and purpose, name your standard, and enforce with checks.
- Use LOD 400 surgically for fabricated items; aim for LOI that matches decisions (design, buy, build, operate).
With a clear LOD/LOI strategy, your BIM model becomes a trustworthy engine for design coordination, procurement, construction, and facility management—not just a 3D picture.
