Why automate families
- Product ranges with many sizes and variants
- Consistent parameters, naming, subcategories and materials
- Fast updates when product data changes
- Families in several Revit versions for different customers
- Reliable data for schedules, specifications and COBie
Approaches
| Approach | Best for |
|---|---|
| Master family + generated types | Products that share one geometry with different dimensions |
| Type catalogues | Very large type counts loaded on demand |
| Families built from templates | Many distinct products with rule-based geometry |
| Parameter and standards updates | Fixing or upgrading existing family libraries |
| Dynamo scripts | Smaller jobs run by BIM staff |
The Family API
The Revit API can create a new family document from a template (.rft), add reference planes, dimensions and geometry, add family parameters, create types and set their values, then save the family or load it into a project. The FamilyManager class handles parameters and types.
Document famDoc = app.NewFamilyDocument(templatePath);
using (Transaction t = new Transaction(famDoc, "Create family"))
{
t.Start();
FamilyManager fm = famDoc.FamilyManager;
FamilyParameter width = fm.AddParameter(
"Width", GroupTypeId.Geometry, SpecTypeId.Length, false);
FamilyType type = fm.NewType("600 x 400");
fm.Set(width, 600 / 304.8); // Revit stores lengths in feet
t.Commit();
}
famDoc.SaveAs(outputPath);Driving families from product data
The source of truth is usually a spreadsheet, product database or ERP. The automation reads each product, chooses the right template or master family, creates types, fills identity data such as manufacturer, model and URL, assigns materials, and names files to your standard. Re-running it after a data change updates the whole library.
Quality checks
Automation should also check its output: parameter names and groups, units, subcategories, level of detail, file size, flexing across all types, and whether families load cleanly into a test project. Catching errors here saves BIM coordinators time later.
Good family automation builds the family and proves it flexes, every time.
Revit versions
Families saved in a newer Revit version cannot be opened in older versions. Automation can build from the oldest supported version and upgrade as needed, or produce separate libraries per version.
Revit family services
See Revit family creation automation and Revit API and add-in development, and read Revit API development for BIM automation.