■ MEP BIM INSIGHTS — BIM GUIDES

LOD 300 vs LOD 400: What Your General Contractor Actually Needs From a BIM Model

When a general contractor asks for a “BIM model,” they rarely specify what level of detail they actually need. And when a BIM team delivers without a clear LOD agreement, someone ends up paying for either too much — or not enough.

LOD 300 and LOD 400 are the two levels where most MEP coordination happens. Understanding the difference isn’t just a technical exercise. It determines your coordination workflow, your fabrication readiness, and ultimately your field installation costs.

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What LOD Actually Means

LOD stands for Level of Development, defined by the BIMForum LOD Specification (aligned with AIA G202). It describes how much information a model element contains — both geometric and non-geometric.

LOD 300: Coordination-Ready

At LOD 300, model elements are defined with enough accuracy to support full MEP coordination. Duct runs, pipe systems, conduit, and equipment are modeled at their actual size and approximate location in 3D space.

What LOD 300 includes:

• Accurate system routing (horizontal and vertical offsets defined)
• Equipment with correct dimensions and connection points
• Penetration locations through structural elements
• Clash detection — reliable and actionable

What LOD 300 does not include:

• Fabrication-level geometry (no hanger details, no exact bend angles)
• Part numbers or manufacturer-specific data
• Installation sequencing information

LOD 300 is the standard for design coordination and clash resolution. If your project goal is to produce a coordinated federated model before construction, LOD 300 is typically what you need — and what most design-phase BIM contracts specify.

LOD 400: Fabrication-Ready

LOD 400 adds fabrication, assembly, and installation detail on top of the coordination geometry from LOD 300. Elements at this level are modeled with enough precision to be manufactured or assembled directly from the model.

What LOD 400 adds:

• Spool drawings and fabrication geometry for mechanical and piping systems
• Hanger and support locations with actual spacing
• Manufacturer-specific equipment models with part numbers
• Installation tolerances reflected in the geometry

Where LOD 400 is used:

• Prefabrication shops producing ductwork or pipe spools
• Projects with mechanical room prefabrication
• Virtual design and construction (VDC) workflows requiring field-level accuracy

LOD 400 is significantly more time-intensive to produce and is typically developed by or in close collaboration with MEP subcontractors — not design-phase engineers.

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The Practical Decision for Your Project

Here is the question to ask before specifying LOD requirements for your MEP model:

If the answer is coordination — resolving clashes between disciplines, producing RFIs, supporting construction administration — LOD 300 is appropriate and cost-effective.

If the answer is fabrication — your MEP subcontractor needs to pull spool drawings from the model — then LOD 400 is warranted for those specific systems.

A common and efficient approach on commercial projects: deliver the full model at LOD 300, then develop LOD 400 for prefabricated mechanical room assemblies and critical routing corridors only. This keeps modeling costs proportional to actual construction value.

A Note on LOD 200

Some owners and architects request LOD 200 for early design-phase coordination. At LOD 200, systems are shown schematically — useful for spatial planning, but not reliable for clash detection or quantity takeoffs. We treat LOD 200 as a design intent model, not a coordination model.

What We Deliver at GEOMETRY-S

Our standard MEP BIM modeling scope is LOD 300, with LOD 400 available for mechanical rooms and prefabricated assemblies upon request. All models are delivered in RVT format (Autodesk Revit), with IFC export available for open BIM workflows.

Every model goes through an internal clash detection review in Navisworks before delivery, with a written clash report included in the handover package.