Millwork BIM Coordination: LOD, Revit Families, and What Fabricators Need to Know

Building Information Modeling has been standard on large commercial projects for over a decade. Millwork shops have historically been the last trade to engage with BIM — producing 2D shop drawings while the structural, mechanical, and architectural teams worked in federated 3D models. That's changing. GCs on healthcare, education, and corporate projects now routinely require millwork subs to deliver Revit models that can be incorporated into coordination workflows. If you're new to BIM requirements, here's what the terms mean and what you actually need to deliver.

What BIM Is — and What It Isn't

Building Information Modeling is the practice of designing and documenting construction using intelligent 3D models where objects carry data — dimensions, material properties, performance characteristics — in addition to geometry. A BIM model isn't just a 3D CAD drawing. The objects in it know what they are: a cabinet is a cabinet, not a collection of lines and surfaces.

The primary BIM platform in US commercial construction is Autodesk Revit. Competing platforms — ArchiCAD, Vectorworks, Tekla — exist and are used on specific project types, but Revit is the default expectation when a GC requires a BIM deliverable from a millwork sub.

BIM is not the same as shop drawings. A shop drawing is a fabrication document — a 2D set showing exactly what will be built and how. A BIM model is a coordination and design tool. The two serve different purposes, and on most commercial projects, both are required.

The BIM Execution Plan

Before the first model is opened, the GC publishes a BIM Execution Plan (BEP or BxP). This document governs BIM on the project. It defines:

• Which trades must contribute BIM models and at what Level of Development
• What software and file formats are required
• The coordination meeting schedule and clash detection process
• File naming conventions, model organization, and delivery schedule
• Who owns what in the federated model

Read the BEP before your scope meeting. It tells you exactly what BIM deliverable you're responsible for — and whether the required LOD is within your current capability. If the BEP requires LOD 400 Revit families and your shop doesn't produce those, that's a scope discussion to have at pre-construction, not after award.

Level of Development — What LOD Actually Means

Level of Development (LOD) is a framework published by BIMForum that defines how complete, specific, and reliable a BIM element is at each stage of a project. LOD is not the same as Level of Detail — it defines how much the information in the model can be relied upon, not just how geometrically detailed it looks.

The LOD levels most relevant to millwork are 200 through 400.

LOD 200 — Approximate Geometry. Elements are represented as generic placeholders with approximate size and location. At LOD 200, a base cabinet run might be a simple rectangular mass in the correct location, the correct approximate height and depth, with a label indicating "casework — see architectural drawings." This level is used in design development to study space utilization and equipment adjacencies. Fabrication decisions cannot be made from LOD 200 elements.

LOD 300 — Specific Geometry. Elements are modeled with specific dimensions, materials, and location that match the design intent. At LOD 300, a cabinet element shows actual width, height, and depth; door and drawer configuration; and material assignments. Non-graphic information attached to the element (manufacturer, model, cost, material type) is project-specific. LOD 300 is the minimum for construction document coordination — it's what the architect's model should contain when it comes to you.

LOD 350 — Construction Coordination. LOD 350 adds interface information — how the element connects to other trades and building systems. For millwork, this means the model shows utility rough-ins (electrical, plumbing connections within casework), blocking requirements communicated to the framing contractor, and clearances to adjacent systems. LOD 350 is the standard for trade coordination — clash detection between millwork, MEP rough-ins, and structural elements happens at this level.

LOD 400 — Fabrication and Assembly. Elements contain the detail necessary for fabrication. For millwork, LOD 400 means the Revit family includes actual construction details: case body dimensions, joinery methods, hardware families, and material specifics at the fabrication level. LOD 400 models can in principle be used to produce shop drawings directly from the model. In practice, most millwork shops produce LOD 400 Revit families alongside — not instead of — traditional shop drawings.

Revit Families for Millwork

Revit organizes all building components into "families." There are three family types: system families (walls, floors, ceilings — built into Revit), in-place families (unique one-off geometry), and loadable families (external .rfa files that can be loaded into any project). Millwork lives in loadable families, specifically in the Casework category.

A Revit casework family has two layers of parameters: type properties (shared by all instances of that family type — overall dimensions, door configuration, material assignments) and instance properties (specific to one placed instance — individual width variation, special notes). When you build a family for a standard base cabinet, the type properties define the standard, and instance properties handle exceptions.

Nested families allow complex assemblies. A base cabinet family might contain nested door panel families, nested hardware families (pulls, hinges), and nested countertop families. Nesting adds complexity and file size — build only what the BEP requires at the specified LOD. Over-modeled families slow coordination workflows and create model management problems for the GC.

Material assignments in Revit families serve two functions: visual (render appearance in views and renderings) and analytical (used by downstream tools for cost estimation and energy analysis). At minimum, assign the structural material (e.g., "MDF — painted" or "hardwood plywood — veneer") and the appearance material for the visible faces. Consult the BEP for specific Revit material naming conventions the project is using.

MEP Coordination and Clash Detection

The primary reason GCs require millwork BIM models is clash detection — identifying physical conflicts between the millwork and other building systems before construction, when they're cheap to fix. The most common conflicts are:

• Millwork countertop or upper cabinet conflicting with a duct run or structural beam
• Under-sink base cabinet blocking a drain or supply line
• Full-height casework in front of an electrical panel requiring clearance
• Lab casework service chase conflicting with a ceiling-mounted sprinkler head
• Reception desk blocking a required clear floor width for egress

Clash detection is performed in Navisworks, Autodesk's model aggregation and coordination platform. The GC or BIM coordinator aggregates all trade models — structural, mechanical, electrical, plumbing, millwork — into a federated Navisworks model (NWD file) and runs automated clash tests. Clashes are exported to a clash report and distributed to trades for resolution.

Your Revit model is typically exported to an NWC file (Navisworks Cache) for import. The GC provides the format and coordinate origin. Coordinate alignment is critical — a model exported from the wrong origin will appear in the wrong location in the federated model, making all clashes meaningless.

IFC — When Revit Isn't the Required Format

On projects that use open BIM workflows, or when the architect works in ArchiCAD or another non-Revit platform, you may be asked to deliver an IFC file instead of (or in addition to) a Revit model. IFC stands for Industry Foundation Classes — an open, vendor-neutral format for exchanging BIM data between different platforms.

Revit can export IFC files, but IFC export quality varies depending on the version (IFC2x3 or IFC4) and export settings. Before exporting IFC, ask the GC which IFC version and which Model View Definition (MVD) they require. A poorly configured IFC export can strip material data, lose object classification, or break parametric relationships — sending a broken IFC to coordination is worse than sending nothing.

COBie — Data for Facilities Management

On projects funded by institutional owners — hospitals, universities, government facilities — the BEP may include a COBie (Construction Operations Building information exchange) requirement. COBie is a structured data format for handing over asset information from the construction team to the facilities management team at project completion.

For millwork, COBie typically means attaching specific data fields to your Revit elements: manufacturer, model number, serial number (if applicable), warranty information, and maintenance requirements. If COBie is required, you'll receive a data template from the GC specifying exactly which fields must be populated and in what format.

BIM vs. Shop Drawings — Which Governs?

On projects requiring both BIM models and shop drawings, the contract documents establish which governs for fabrication. In most commercial contracts, approved shop drawings govern fabrication — the BIM model is a coordination tool, and any discrepancy between the Revit model and the approved shop drawings is resolved in favor of the shop drawings.

This means your BIM model and your Revit millwork deliverable should be consistent with your shop drawings, but the shop drawings remain the fabrication document. If coordination requires a change — a cabinet depth reduced to avoid a duct — that change must be reflected in a revised shop drawing submittal, not just in the BIM model. For more on the 2D vs. 3D decision and when each tool is appropriate, see our breakdown of CAD vs. Revit for millwork. On projects that go through substantial field changes, the BIM model may also need to be updated post-installation — see our guide on millwork as-built drawings for how that process works.

What a Realistic Millwork BIM Deliverable Looks Like

For most millwork subcontractors, a realistic BIM deliverable consists of:

• Loadable Revit families (.rfa) built to the specified LOD, in the Casework category
• A project model (.rvt) with families placed at correct locations, coordinated with the GC's shared coordinates
• An NWC export for Navisworks coordination
• Material assignments consistent with the spec
• Parameters populated per the BEP's data requirements

If your shop doesn't have in-house Revit capacity, outsourcing the BIM deliverable alongside your millwork shop drawings to a single drafting partner keeps geometry consistent between both deliverables and eliminates the coordination overhead of managing two separate vendors. See our Revit modeling pricing for what this typically costs on commercial projects.