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LOD & LOIN Frameworks

AIA G202 / BIMForum LOD Spec / ISO 7817-1:2024 · Level of Development & Level of Information Need definitions

There are three commonly-used frameworks for specifying 'how detailed should this BIM object be': the AIA LOD numbering (100-500), the BIMForum LOD Specification, and the newer ISO 7817-1 Level of Information Need (LOIN). They all answer the same question, in different ways. India has no national framework — most projects use AIA LOD or BIMForum.

AIA G202 →ISO 7817-1 →

23 items shown

AIA LOD Numbering (most-cited globally)

Defined in AIA G202-2013. Single-number scale that bundles geometry and information.

Level	Geometry	Information	Example (Column)	Use Case
LOD 100	Symbolic / mass	Generic, project-wide	Generic mass model — no real dimensions	Concept stage, area takeoff, schematic
LOD 200	Generic placeholder, approximate size & position	Approximate quantities	Rectangular box at correct location, indicative size	Schematic design, preliminary cost
LOD 300	Specific size, shape, location, orientation	Documented quantities + design intent	300×400 column, M30 grade, exact location	Design development, tender, coordination
LOD 350	LOD 300 + interfaces with other systems modelled	Joints, connections, openings shown	Column with beam-column joint, connection detailing	Construction documents, clash detection
LOD 400	Fabrication-ready: real dimensions of every component	Manufacturing data, assembly, installation	Column with reinforcement layout, every bar cut to size	Shop drawings, prefabrication, install
LOD 500	As-built — verified against constructed reality	Verified, with manufacturer data, warranty info	As-installed column with pour-record, NDT history, occupancy data	Handover, FM, asset management

BIMForum LOD Specification (annual reference)

Free PDF published yearly by BIMForum (USA). The most practical reference — gives object-by-object guidance.

Level	Geometry	Information	Example (Column)	Use Case
Object-specific	Defined per discipline & object type	Structural, architectural, MEP elements separately	See Concrete > Cast-in-Place > Column section in the spec PDF	Definitive reference for what 'LOD 350' actually means for, say, a steel connection
Released annually	Updates with industry practice	Latest is 2024 edition	—	Always cite the YEAR of the spec when referencing LOD in tender
Free download	—	—	bimforum.org/lod	Mandatory reference for any serious BIM tender

ISO 7817-1 Level of Information Need (LOIN)

Replaces BS EN 17412-1:2020. Modern, more precise — but slower adoption.

Level	Geometry	Information	Example (Column)	Use Case
Concept	—	—	—	LOIN replaces single-number LOD with THREE independent dimensions
Geometric (G)	G1=detail; G2=symbolic; G3=basic; G4=detailed	—	Column G3 = real dimensions, no rebar	How much geometric detail
Alphanumerical (A)	—	A1=basic; A2=structured; A3=full property set	Column A3 = grade, fy, fck, full property bag	How rich the metadata
Documentation (D)	—	D1=catalog; D2=spec sheet; D3=full documentation	Column D2 = pour record, mill cert	What attached documents
Why it's better	Independent axes	Not bundled	You can need rich properties (A4) but rough geometry (G2)	AIA LOD forces all 3 to move together — LOIN doesn't

Mapping Between Frameworks

Level	Geometry	Information	Example (Column)	Use Case
LOD 100	G1-G2	A1, D1	Symbolic	Concept design
LOD 200	G2-G3	A1-A2, D1	Schematic	Preliminary design
LOD 300	G3	A2-A3, D1-D2	Detailed design	Tender, coordination
LOD 350	G3-G4	A3, D2	Constructable	Construction docs
LOD 400	G4	A3-A4, D2-D3	Fabrication	Shop drawings
LOD 500	G3-G4	A4, D3	As-built	Handover, FM

India Practice (verified facts only)

Level	Geometry	Information	Example (Column)	Use Case
Indian Standard?	—	—	NO	BIS has not published an IS standard on LOD or LOIN as of 2026
Most-cited in tenders	AIA LOD 100-500	Single number	—	Borrowed from AIA / BIMForum because no Indian alternative
What to use today	AIA LOD numbering	+ BIMForum spec	—	Cite both: 'LOD 300 per BIMForum 2024 Spec'

Notes

• AIA LOD is older and more widely cited. BIMForum is the practical reference. ISO 7817-1 LOIN is newer and more precise but adoption lags.

• Always tie LOD to a milestone, NOT to a project — different milestones need different LODs

• LOD does NOT increase monotonically — the as-built (LOD 500) often has LESS rebar detail than the shop drawing (LOD 400)

• If your tender says 'LOD 400 throughout' without specifying object types or milestones, push back — that's not a real specification

• On India projects, default to BIMForum 2024 LOD Specification for any disputes about what 'LOD 300' means for a specific object

• Free download: bimforum.org/lod

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