LOD 100–500: What Each Level of Detail Means in Irish BIM

Level of Development (LOD) is the most frequently misunderstood concept in Irish BIM practice. "LOD 300" appears in HSE Capital Programme EIRs, OGP BIM Framework documents and Irish NDP tender briefs — but many Irish architects, engineers and project managers who encounter this term cannot clearly articulate what LOD 300 means in terms of what the model contains, what a contractor can reliably derive from it, and how it differs from LOD 200 or LOD 400. This guide explains the BIM LOD levels for Irish projects in plain, practical terms, with specific reference to RIAI work stage alignment and ISO 19650 requirements.

What Is Level of Development (LOD) in BIM?

Level of Development defines how much information is reliably included in a BIM model element at any given point in the design process — from a conceptual placeholder (LOD 100) to a fully verified as-built representation (LOD 500). LOD is not a single property of a whole model — it is applied element by element. A structural frame may be at LOD 300 while architectural finishes are still at LOD 200 in the same model at the same design stage.

LOD matters because it controls what a contractor can reliably derive from a model. A LOD 200 element has approximate size, shape and location — useful for spatial coordination but not for pricing. A LOD 300 element is dimensioned, specified and coordinated — a contractor can price from it. Specifying LOD 300 when you've only produced LOD 200 misleads contractors and creates liability for the design team.

LOD 100 — Conceptual Massing

LOD 100 is a conceptual placeholder — an object in the model that represents the existence of an element but not its detailed geometry, size, shape or specification. A LOD 100 fire alarm panel is a box in a plant room at approximately the right location. A LOD 100 AHU is a box of approximately the right volume. At this level, the model supports concept design decision-making and spatial planning but nothing more. RIAI Stage 1 ELV models are typically at LOD 100.

LOD 200 — Approximate Geometry and Location

LOD 200 elements have approximate size, shape, location and orientation — sufficient for spatial coordination and design intent communication but not for quantification. A LOD 200 fire alarm containment route shows the approximate path, approximate tray width and approximate height. It is sufficient to identify potential clashes with structural elements and MEP services — which is why Stage 2 BIM coordination models are typically at LOD 200. On Irish NDP projects, LOD 200 is the minimum for Stage 2–3 discipline model exchange and clash detection.

LOD 300 — Dimensioned and Specified

LOD 300 is the most operationally significant level for Irish construction procurement. A LOD 300 element has accurate geometry (dimensioned, sized, located and oriented to the design intent), full specification (manufacturer type or performance specification), and is spatially coordinated within the federated model. A LOD 300 fire alarm panel is the correct size, in the correct location, with the correct panel specification applied — a contractor can price it and order it.

LOD 300 is the standard for Irish NDP tender stage (RIAI Stage 4) — it is what HSE Capital Programme, OGP and Department of Education EIRs specify as the minimum for model issue at tender. LOD 300 models, when properly clash-detected, should allow contractors to price accurately without large contingencies for coordination risk.

LOD 400 — Fabrication and Installation-Ready

LOD 400 elements include manufacturer-specific geometry and all information required for fabrication, installation and assembly. A LOD 400 cable tray section has the exact manufacturer model, exact dimensions, connection details and installation sequence information. LOD 400 is typically required for specialist or prefabricated elements during the construction stage — structural steel connections, MEP prefabricated modules, and data centre containment systems in Dublin and Cork are common LOD 400 scopes on Irish NDP projects.

LOD 500 — As-Built and Verified

LOD 500 elements have been verified against the actual installed condition — they represent the building as built, not as designed. Dimensions, locations, manufacturer data, installation dates and commissioning records are attached to each element. LOD 500 is the handover standard for ISO 19650-mandated Irish NDP projects, supporting facilities management, SEAI energy monitoring and digital twin integration for the operational life of the building.

LOD vs LOIN — The ISO 19650 Shift in Terminology

ISO 19650 introduces a refinement of LOD called LOIN (Level of Information Need), which separates geometric detail (LOG — Level of Geometry) from information content (LOI — Level of Information). This allows a structural element to have high LOI (full specification and cost data) at an early stage while retaining approximate geometry (LOD 200 equivalent). Irish NDP projects are progressively adopting LOIN terminology as it appears in updated OGP and HSE EIR documents. In practice, for most current Irish NDP commissions, LOD remains the working language — but LOIN awareness is becoming professionally important.

LOD by RIAI Work Stage — The Irish Alignment

• RIAI Stage 1–2: LOD 100–200 — conceptual placeholders and spatial coordination concept
• RIAI Stage 3: LOD 200–300 — developing coordination, approaching LOD 300 by Stage 3 completion
• RIAI Stage 4 (Tender): LOD 300 — the standard for Irish NDP tender issue
• RIAI Stage 5 (Construction): LOD 400 — fabrication-ready for specialist elements
• RIAI Stage 6 (Handover): LOD 500 — as-built and verified

ASDV delivers ELV discipline BIM models to the correct LOD at each RIAI stage gate for Irish NDP projects. See our BIM support services Ireland page and our ELV deliverables by RIAI stage guide for the full deliverable progression.