How to Create Scalable Families in Revit

Part 1: Understanding the Need for Scalable Families

Revit is a powerful BIM tool designed for precision and parametric flexibility. However, there are cases where scalability is necessary but not easily achievable using standard parametric controls. Here’s why we need scalable families and when they are most useful:

Why Do We Need Scalable Families?

1. Objects That Maintain Fixed Proportions
   Some elements are not meant to change dimensionally in different directions. For example, a sculptural object should not stretch unpredictably; it should scale uniformly across all dimensions.

2. Complex and Curved Geometry
   Highly detailed objects like sculptures, furniture with intricate carvings, or detailed product models cannot be easily controlled with parametric formulas. Trying to constrain them often results in unwanted distortions or impractical constraints.

3. Objects Used at Different Scales
   Items like trees, human figures, decorative elements, and entourage models are typically required at different scales depending on the project phase. In Enscape, SketchUp, AutoCAD, and other 3D software, scaling is a simple process—so why not in Revit?

Why Is This a Challenge in Revit?

Unlike other software, Revit families are built with a fixed modeling environment, meaning you can’t simply scale a family like you would in SketchUp or AutoCAD. Revit’s parametric framework allows for dimensional control, but it does not inherently support uniform scaling across all axes for complex objects.

• Regular families do not allow for an overall scaling parameter.

• Curved and imported geometry is difficult to control parametrically.

• Manual resizing often leads to distorted results.

❌ Since there’s no native "scale" feature in the Revit Family Editor, we had to find a workaround to achieve this effect.

💡 How Did We Solve This?

To create scalable families, we use a unique nesting technique with the Planting Category. Here's how:

1. Model the Family in the Planting Category
   The Planting Category in Revit has a built-in scaling ability that is not available in other categories. This allows the family to be resized uniformly without distorting proportions.

2. Nest the Planting Family Inside Another Planting Family
   Instead of directly using the first planting family, we nest it inside another planting family to maintain scaling consistency. This ensures that scaling remains controlled and behaves correctly.

   

3. Nest the Double-Nested Planting Family into the Target Category
   Once the scalable object is created, the double-nested planting family is placed inside the intended category (e.g., Furniture, Generic Models, Site Components, etc.). 

   This ensures the family behaves correctly in scheduling, tagging, and visibility graphics while still maintaining the ability to scale.
   
   
   

4. Test and Control Scaling in the Host Family
   By using the Height Parameter from the Planting Category, the object scales proportionally across all dimensions when resized.

   This approach allows you to create scalable trees, furniture, play equipment, sculptures, and more.
   
   
   

Download an Example Family

To see how this method works in action, download our Dog House Family from the Dog Park Collection and explore how scalable Revit families can improve your workflow:

👉 Download Dog House Family

By leveraging this technique, you can achieve a fully scalable Revit family while ensuring proper categorization and scheduling.