■ MEP BIM INSIGHTS — BIM GUIDES

LOD 350: The Coordination Level Everyone Skips

Most BIM scopes name LOD 300 or LOD 400. LOD 350 — the level in between — is often left out of the conversation entirely. Yet for multi-discipline coordination, it is frequently the level that actually matters. This article explains what LOD 350 adds, why it exists, and when it is the right target.

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A Quick Recap of the LOD Scale

The Level of Development scale (as defined by the BIMForum / AIA framework) describes how much a model element can be relied upon:

Level	What it means
LOD 100	Conceptual — symbolic representation, no reliable geometry
LOD 200	Design intent — approximate size, shape, location
LOD 300	Accurate geometry — correct size, shape, location; reliable for coordination
LOD 350	LOD 300 plus interfaces — connections, supports, and how elements meet other systems
LOD 400	Fabrication — detailing, assembly, and installation information

The jump people notice is 300 to 400. The jump they miss is 300 to 350 — and it is a smaller, cheaper step that solves a specific coordination problem.

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What LOD 350 Actually Adds

The defining addition at LOD 350 is interfaces between elements — the parts that connect one component to another, or to another discipline’s work. LOD 300 models each element accurately in isolation. LOD 350 models how they physically meet.

Concretely, LOD 350 includes items LOD 300 typically does not:

• Supports and hangers — the rods, trapezes, and brackets that hold pipe, duct, and conduit. At LOD 300 these are often absent; at LOD 350 they occupy real space in the model.
• Connections and interfaces — how a duct meets an air handler, how a pipe connects to equipment, how systems tie together.
• Insulation thickness where it affects clearance.
• Cross-discipline attachment — where MEP attaches to structure, and the space that hardware needs.

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Why LOD 350 Is the Coordination Sweet Spot

LOD 300 is described as “reliable for coordination,” and it is — for the elements themselves. But real installation conflicts frequently occur at the connections and supports, not the main runs. Two ducts might clear each other perfectly while their support steel occupies the same space. A pipe might have room until you account for the hanger rod dropping from the structure above.

LOD 350 catches exactly these conflicts. It is detailed enough to reveal installation-level clashes, without the full fabrication effort (and cost) of LOD 400. For most commercial multi-trade coordination, this is the level that produces a genuinely buildable model.

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LOD 350 vs 400: Knowing Where to Stop

Aspect	LOD 350	LOD 400
Purpose	Coordination with interfaces	Fabrication and assembly
Supports	Modeled for coordination	Detailed for fabrication
Connections	Shown as interfaces	Full connection detail
Effort / cost	Moderate	High
Best for	Multi-trade coordination	Prefabrication, spooling

LOD 400 is warranted for systems that will be prefabricated — where spool drawings and fabrication data are needed. But modeling an entire project at LOD 400 when only coordination is required is overkill: it costs more and delivers detail no one on the project will use. LOD 350 is often the right ceiling for the general coordination model, with LOD 400 applied selectively to prefabricated assemblies.

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Specifying LOD 350 in the BEP

Because LOD 350 is frequently omitted from templates, it must be named explicitly in the BIM Execution Plan and the LOD matrix. Points to define:

• Which disciplines model supports and hangers, and to what standard
• Whether seismic bracing is included (it often is, at LOD 350)
• How interfaces between disciplines are handled at boundaries
• Which systems, if any, go to LOD 400 for fabrication

Our Approach at GEOMETRY-S

For multi-trade coordination we target LOD 350 — modeling supports, hangers, and interfaces so installation-level clashes surface in the model rather than in the field. Where systems will be prefabricated, we develop those to LOD 400 selectively. The result is a coordination model that reflects what actually gets installed, without the cost of fabricating detail no one needs.