What is an RFA file?
In Revit, every element of a building model belongs to a family. Loadable families, such as doors, windows, furniture, lighting fixtures or mechanical equipment, are stored in their own RFA files. Each family contains the 3D geometry of the component, its 2D representations, and the parameters that define its different types, for example sizes, materials or performance data.
RFA is one of the four main native Revit file formats, alongside RVT for projects, RTE for project templates and RFT for family templates. The format is proprietary and tied to the Revit version that saved it: a family saved in a newer Revit release cannot be opened in an older one.
Native Revit file types
| Extension | File type | Content |
| .rvt | Project | The complete building model, with all placed families, views and sheets |
| .rfa | Family | A reusable component with its geometry, types and parameters |
| .rte | Project template | Default settings and content used to start new projects |
| .rft | Family template | Starting point for creating new families of a given category |
What Is RFA Used For? Applications and Industry Use Cases
RFA files are used throughout architecture, engineering and construction. Building product manufacturers publish their doors, windows, HVAC units and fixtures as Revit families so that designers can place them in their projects, and design firms maintain libraries of families that encode their standards.
For software developers, reading RFA files makes it possible to bring manufacturer content and standard components into non-Autodesk applications for coordination, clash detection, visualization or fabrication. Writing RFA files lets applications publish their own geometry as Revit families, for example to deliver products designed in a mechanical CAD system to BIM users.
Challenges or Common Pitfalls
Revit families are parametric and tightly bound to Revit's own logic. Outside Revit, a translator typically delivers the geometry and properties of a family rather than its live parametric behavior, so applications should be clear about whether they need a fixed shape or editable types.
Version locking is another constraint, since families saved in a newer Revit release cannot be opened in older ones. When geometry is written back to RFA from another system, it is usually converted to meshes, which is fine for coordination and visualization but not for further parametric editing in Revit.
How Spatial Helps
Our 3D InterOp SDK reads Revit family (.rfa) and project (.rvt) files through its UConnect and Connect interfaces, and since Release 2025 1.0.1 it can also write RFA files. Data can be imported into CGM Modeler or 3D ACIS Modeler.
On import, 3D InterOp delivers exact B-rep geometry and mesh visualization data, places each BIM element as an instance with its name, visibility, position and color, and carries color, visibility and persistent names at instance, face and edge level. It reads units, view names and types, with options to filter by view, and since Release 2023 1.0 it retrieves object properties as user-defined attributes and imports shared coordinates such as project base points and survey points.
On export, the Revit Writer creates a family file from your model: solids and sheets are written as triangle meshes, assemblies are flattened, body-level color and document-level attributes are kept, and units are written in millimeters. Writing RVT project files is not supported.