Revit Family Creation — What It Is and When to Outsource It

[edit] 1. Overview

Revit family creation is the process of building parametric BIM objects within Autodesk Revit — the individual components, from a structural column to a VAV box, that populate a building model and carry both geometric and data attributes. Families are not static shapes. They are rule-based objects: dimension parameters drive geometry, type catalogues allow a single family to represent hundreds of product variants, and connector logic enables MEP components to attach to system networks.
Poor family construction is one of the most persistent sources of model performance problems, coordination errors, and failed IFC exports in BIM workflows. A family that looks correct in a 3D view may carry incorrect category assignments, broken parameter references, or geometry that does not respond to project-level settings — all of which propagate errors across schedules, drawings, and downstream analysis outputs.
Family creation sits at the intersection of Revit software proficiency, building industry knowledge, and an understanding of how models are used across disciplines. It is a specialised skill that many AEC practices outsource rather than maintain in-house.

[edit] 2. What a Revit family is

In Revit, all model content belongs to one of three family categories: System Families, Loadable Families, and In-Place Families.
System Families are built into the Revit software and cannot be exported or transferred as standalone files. Walls, floors, roofs, ceilings, and stairs are system families. Their properties are controlled through type parameters within a project, but their underlying logic is fixed by Autodesk.
Loadable Families — also called component families — are created externally in the Revit Family Editor and saved as .RFA files. They can be loaded into any project, shared across teams, and published to BIM content libraries. Doors, windows, structural steel sections, lighting fixtures, mechanical equipment, plumbing fittings, furniture, and annotation tags are all loadable families. These are the families that require dedicated creation work.
In-Place Families are unique geometry built directly within a project for elements that will not recur elsewhere. They carry performance penalties and do not support scheduling or tagging in the same way as loadable families, so their use is limited to non-repeating bespoke elements — a specific curved reception desk, a one-off structural transfer member.

[edit] 3. Family types and their technical distinctions

Within loadable families, the complexity and technical demands vary significantly by discipline and intended use. The table below outlines the primary distinctions:

MEP families carry the highest technical complexity because connector definitions must match system routing logic. An air terminal family with an incorrect duct connector size will prevent automated system calculations from running correctly in Revit's MEP tools.

[edit] 4. The family creation process

A Revit family is built in the Family Editor, a separate authoring environment within the Revit software. The creation sequence follows a consistent structure regardless of family type:
The designer selects a family template (.RFT file) that matches the intended category and hosting behaviour — ceiling-based, face-based, wall-hosted, or standalone. Template selection determines which built-in parameters are available and how the family will behave when placed in a project.
Reference planes and reference lines establish the geometric skeleton. Dimensions are drawn between reference planes, then converted to parameters — either instance parameters (which can vary per placement) or type parameters (which apply across all instances of a given type). These parameters drive the geometry, so changes to parameter values propagate through the model automatically.
Solid and void geometry is modelled using Revit's native solid creation tools: extrusion, blend, revolve, sweep, and swept blend. Voids cut through solids to create openings, recesses, and profiles. Material parameters are assigned so that surface appearance and schedule data respond to project settings.
Connector elements — for MEP families — are placed at each connection point and assigned the correct system type, size, flow direction, and pressure properties. Subcategories control the visibility of geometry across different detail levels (coarse, medium, fine), so that model performance is not compromised at small scales.
The family is tested in a blank project file before delivery, verifying that it places correctly, schedules correctly, tags correctly, and exports to IFC without errors.

[edit] 5. Discipline-specific family requirements

Structural families must carry accurate section profiles for quantity take-off and fabrication. A steel I-beam family built from approximate dimensions rather than the actual section properties from the SCI Blue Book (UK) or AISC Steel Construction Manual (US) will produce incorrect weight schedules and section verification outputs. For Scan to BIM projects on existing structures, structural families are often built to match non-standard or historic section profiles captured from point cloud data.
MEP families require connector data that integrates with Revit's system calculation tools. A duct connector assigned the wrong system classification will break pressure drop calculations. A pipe fitting without a correct nominal diameter parameter cannot be sized by the routing tools. These are not cosmetic errors — they prevent downstream engineering analysis from running.
Architectural families on heritage projects often require non-standard geometry: sash windows with ovolo moulding profiles, panelled doors with raised-and-fielded geometry, cast iron column profiles. These elements require swept blend or lofted geometry rather than simple extrusion, and benefit from a modeller who understands both Revit's geometry tools and the architectural language of historic building types.
Annotation families — title blocks, tag families, keynote labels — are frequently underestimated in scope. A title block family for a multi-disciplinary practice may contain 40 or more parameter-driven label fields, revision tables, and sheet format variants. Errors in annotation families produce incorrect drawing outputs across every sheet in a project set.

[edit] 6. When to build in-house versus outsource

The decision to build Revit families in-house or outsource them depends on three factors: the volume of content required, the technical complexity of individual families, and the capacity of in-house Revit technicians to carry family creation work alongside project delivery.
In-house family creation is practical when the required content is standard, derivable from Revit's built-in families with minor modification, and needed across recurring project types where the investment in creation time recurs over many projects.
Outsourcing is the rational choice when the volume of bespoke content is high (for example, a manufacturer requiring 200+ product families for a BIM content library), the technical complexity exceeds the current team's Revit skill level (complex MEP connector families, adaptive structural components), or project timelines do not allow for the internal resource time that family creation requires.
Outsourcing is also common in Scan to BIM workflows, where modellers convert point cloud data into as-built Revit models. Non-standard elements — historic structural sections, bespoke joinery profiles, irregular MEP equipment — require custom families that are not available in standard libraries. These are typically created as part of the modelling scope.
The practical workflow for outsourced family creation involves sharing a manufacturer data sheet or measured drawings, a brief specifying the required LOD and parameter set, and a naming convention that matches the practice's Revit template. The receiving team builds, tests, and delivers .RFA files that load directly into the project without rework.

[edit] 7. What to specify when outsourcing

A family creation brief should define: the Revit version the family must be compatible with (families created in later versions cannot be loaded into earlier project versions), the category and subcategory assignment, the parameter names and data types (text, length, material, yes/no), the required type catalogue if multiple product variants are needed, and the connector data for MEP content.
It should also specify the geometry LOD: a coarse representation for planning and massing, a medium representation for coordination, or a fine representation with full geometric fidelity for construction documentation. Requesting fine-level geometry for all families in a large project model is a common cause of performance problems — detail should match the intended use.
Verification on delivery should check that the family places correctly in the target host environment, that all parameters drive geometry as intended, that schedule outputs are correct, and that IFC export produces the expected element classification and property set data.

[edit] 8. Common errors in family creation

Incorrect category assignment is the most frequent error. A column modelled as Generic Model rather than Structural Columns will not appear in structural schedules, will not respond to structural analytical settings, and will export to IFC as a generic object rather than a column. Category drives behaviour throughout the model.
Reference plane misalignment causes families to insert at incorrect positions relative to host elements. A door family whose origin reference plane does not align with the door leaf centreline will not sit correctly in wall openings when dimensions are applied.
Hardcoded dimensions — geometry built with fixed dimensions rather than parameter-driven references — cannot be resized through type properties. A family discovered to have hardcoded geometry must be rebuilt from scratch rather than simply edited.
Overbuilt geometry at coarse detail level loads unnecessary polygon count into every view, degrading model performance across a project. The coarse representation of a complex piece of mechanical plant should be a bounding box, not full geometric detail.
Missing or mis-typed IFC property sets produce non-compliant IFC exports. For projects operating under ISO 19650 workflows or public sector BIM requirements, families must carry the correct IFC classification and property set structure defined in the project's BIM Execution Plan.

[edit] References / Further reading

• Autodesk. The Revit Family Editor — Autodesk Knowledge Network, autodesk.com
• buildingSMART International. IFC Schema Specification — standards.buildingsmart.org
• NBS. National BIM Library Family Standards — nationalbimlib.com (UK content standard for loadable families)
• UK BIM Framework. Information Management according to BS EN ISO 19650 — ukbimframework.org
• SCI (Steel Construction Institute). Blue Book — Steel Section Properties — steelbiz.org
• AISC. Steel Construction Manual, 16th Edition — aisc.org
• ViBIM Revit family creation services — outsourced Revit family creation for architectural, structural, and MEP disciplines, including bespoke content for Scan to BIM and as-built modelling projects