LOD in BIM Explained: What LOD 100, 200, 300, and 400 Lock You Into
LOD — Level of Development — determines what architects can rely on at each BIM model stage. Getting the sequence wrong locks in supplier decisions before the design is ready — and costs weeks of rework on facades
LOD 300 and LOD 400 are not consecutive steps in a single escalation — they mark a formal handoff between architect and fabricator. LOD 300 is the architect’s deliverable: design intent locked, geometry measurable, dimensions contractually reliable. LOD 400 is the fabricator’s: manufacturer-specific, shop-drawing ready, production-authorized. The line between them is not about how much detail is in the model. It’s about who owns the model element and what they’re authorized to do with it.
LOD 300 and LOD 400 Are Not Points on a Spectrum — They Are a Handoff
LOD 300 elements carry measurable quantity, size, shape, location, and orientation — the level at which architects generate construction documents and permit submissions. Dimensions can be taken directly from the model without separate call-outs. Contractors, consultants, and building departments can contractually rely on what is modeled. For a full overview of the LOD scale from 100 through 400, see LOD 100, 200, 300, and 400 explained.
LOD 400 adds the fabrication layer: bolt hole locations, weld plate dimensions, hanger assembly specifications, and manufacturer part numbers. At LOD 400, shop drawing production is possible. So is prefabrication.
The BIM Forum Level of Development Specification treats LOD and responsibility as separate variables — a critical distinction. AIA Contract Document G202™ formalizes this through the Model Element Table, which assigns LOD targets and responsible parties per element, per project phase. The architect develops to LOD 300. The fabricator or contractor advances those elements to LOD 400 — after the design is frozen and a manufacturer is selected.
Teams that conflate the two end up with architects producing fabrication detail during design development: the wrong party, the wrong information, at the wrong time.
LOD 350 — The Coordination Threshold BIM Forum Added for Exactly This Problem
LOD 350 is not LOD 300 with more geometry. BIM Forum introduced LOD 350 in the 2013 LOD Specification to fill a specific gap: LOD 300 leaves system interfaces ambiguous, while LOD 400 requires manufacturer data that only becomes available after a fabricator is selected. LOD 350 sits between the two and defines what must be resolved before fabrication modeling begins.
For facade and curtain wall systems, LOD 350 locks in:
- Anchor point locations relative to the structural frame
- Thermal break positions and edge-of-slab conditions
- Transitions to floor and roof assemblies
- Connections to adjacent building systems — cladding transitions, parapet details, window-to-wall interfaces
LOD 350 coordination requires input from both the architect and the facade contractor. It does not require a manufacturer selection — that’s the point. LOD 350 defines what needs to be resolved before fabrication begins, without requiring the fabricator to have been chosen. Leaving LOD 350 undefined in the BIM Execution Plan typically means those interface decisions get resolved during shop drawing review — the most expensive place to find them.
What Goes Wrong When Architects Are Pushed to Produce LOD 400
The failure pattern is predictable. A compressed schedule pushes the facade team to LOD 400 during design development, before schematic design is approved by the owner. To model at LOD 400, the team links the Revit model to a specific manufacturer’s component catalog: panel profiles, anchor configurations, hardware specifications. At that point, the model is no longer a generic curtain wall system — it’s a documented commitment to one manufacturer’s product line.
When the design changes — and on complex facades, it usually does — three things happen simultaneously. Shop drawings become obsolete. The fabrication sequence needs to be rebuilt from different panel geometry. Procurement re-opens. These are not sequential problems; they happen in parallel and multiply each other.
That rework is not caused by the design — it’s generated by an LOD sequencing decision made weeks or months earlier.
The LOD 400 Timing Problem Is Worst on Unitized Curtain Wall
Unitized curtain wall systems — fabricated off-site and installed as complete floor-to-floor panels — require LOD 400 before production begins. Each panel is a discrete manufactured component: the factory needs exact dimensions, anchor locations, and hardware specifications before cutting aluminum extrusions. That production requirement creates schedule pressure to reach LOD 400 early.
The problem is that “early” and “before design approval” are not the same thing. Large-scale unitized curtain wall projects typically carry fabrication lead times of 6–12 months. That lead time creates pressure to lock in panel specifications before the owner has signed off on the facade design. A module height change, a material zone shift, or a floor plate adjustment at that stage means rebuilding the fabrication model from scratch — not revising it.
For how this sequencing risk plays out across project phases, see what LOD architects actually need.
How to Sequence LOD on a Facade Project Without Getting Burned
The correct sequencing aligns LOD escalation with decision authority — not schedule pressure. For a full project-phase breakdown, see what LOD architects actually need at each stage.
- Schematic Design: LOD 100–200. Massing, approximate layout, no manufacturer commitment. Facade rhythm, module proportions, and material zone logic explored without locking anything in.
- Design Development: LOD 200–300. System type committed — unitized vs. stick-built — dimension grid established, material assignments confirmed. The architect owns this output.
- Construction Documents / Permit: LOD 300. Measurable geometry, precise dimensions, contractually reliable. Sufficient for permit submission and consultant coordination.
- Pre-Fabrication Coordination: LOD 350. System interfaces resolved between architect and facade contractor. Anchor locations, slab edge conditions, and adjacent assembly transitions locked in. No manufacturer selection required yet.
- Fabrication: LOD 400. Fabricator’s deliverable, produced after the design is frozen and the manufacturer is selected.
The BIM Execution Plan should assign LOD targets per element, per phase, and per responsible party — explicitly. Leaving any of those three variables unassigned creates the conditions for premature escalation.
Designing Facade Systems at LOD 100 Makes the LOD 300 Handoff Cleaner
Some facade teams have restructured their workflow to stay deliberately at LOD 100 through schematic design — keeping the model fast, flexible, and manufacturer-neutral until the design direction is approved.
Kora Studio — a Revit-native facade design plugin — is built around this approach. Kora Studio Grid Editor defines panel spacing, floor-to-floor module heights, and cladding zones inside Revit using formula-driven dimension fields, without linking to any manufacturer’s panel catalog. The facade schedule, material assignments, and panel layout update parametrically as the design evolves. The model stays coordinated without escalating to LOD 300 before the design is stable.
When schematic design is complete and the design direction is approved, the Kora Studio LOD 100 model becomes the foundation for LOD 300 construction documentation — not a throwaway file rebuilt from scratch. For the Revit curtain wall architecture the Kora workflow builds on, see curtain wall system and family setup in Revit.
If your facade team is spending construction document hours rebuilding schematic decisions, the issue is LOD sequencing — not the design itself. Book a demo to see what a LOD 100 facade workflow looks like inside Revit.
FAQ
LOD (Level of Development) defines the geometric reliability and dimensional accuracy of a BIM model element. LOI (Level of Information) defines the non-geometric data attached to that element — manufacturer specifications, cost codes, performance data, maintenance schedules. Both are addressed in the BIM Forum Level of Development Specification 2024. The two scales are independent: a LOD 300 curtain wall panel can carry very low LOI if no material data is attached, or high LOI if full performance documentation is included.
Most jurisdictions accept permit documents derived from LOD 300 models. LOD 300 provides measurable geometry, exact dimensions, and precise locations — sufficient for building departments to evaluate compliance with zoning, fire separation, and structural requirements. LOD 200 is generally not sufficient for permit purposes, as quantities and dimensions are still approximate at that level. Requirements vary by jurisdiction; confirm with the authority having jurisdiction before submitting.
Yes — and mixed LOD is standard practice on complex projects. A BIM execution plan typically assigns different LOD targets to different systems and phases: structural elements may reach LOD 300 while facade panels remain at LOD 200 during schematic design. The BIM Forum LOD Specification is designed to accommodate this approach. The coordination risk arises when teams assume all systems are at the same LOD when they are not — clear LOD assignments per system in the BIM execution plan are essential.
For design exploration and schematic coordination: LOD 100–200. For construction documents and permit submission: LOD 300. For fabrication and shop drawing production: LOD 400. The LOD 350 threshold — where system interfaces, anchoring points, and transitions to adjacent assemblies are locked in — applies specifically to facade and curtain wall systems and sits between LOD 300 and LOD 400.
LOD 100 is most valuable when treated as an active design tool — not a step to skip on the way to LOD 300. For facade systems in particular, LOD 100 is the phase where the most consequential decisions are made: panel module proportions, floor-to-floor heights, material zone logic, and overall facade rhythm. Making these decisions at LOD 100 — before any manufacturer commitment — preserves flexibility and reduces rework downstream.
