Workflow: Creating Loadable Families

To create a custom element for use in one or more models, create a loadable family.

Elements in Revit LT are also referred to as families. The family contains the geometric definition of the element and the parameters used by the element. Each instance of an element is defined and controlled by the family. Loadable families are created in external RFA files and imported, or loaded, in your projects.

Plan the Family and Perform Preliminary Work

Before creating a loadable family, you must plan and make decisions about the way a family is going to behave in the model. Planning behaviors and listing the information needed for the family will help you make decisions as you create the family in the Family Editor.

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Plan

Understand the workflow used when creating a family. Workflow: Loadable Families	Understand the tools and terminology used in the Family Editor. About the Family Editor	Plan the geometry, the detail level, parameters, and behaviors needed for the family. Plan a Loadable Family	Learn about family templates and how they affect the behavior of the family in model files. Video: About Family Templates

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Begin Work on the Family

Choose a template (RFT) that matches the needs of the new family. Create a Family from a Template	The origin of a family defines the position of the geometry when it is loaded into a model. Define the family origin at the intersection of major reference planes. Define the Family Origin	Sketch more reference planes to establish a framework for the family. Lay Out Reference Planes	Define priorities for each reference plane to affect family behavior in the model and how the family can be dimensioned. Define Priorities for Reference Planes

Create Geometry and Parameters

Create geometry and parameters in the family. As you create parametric geometry, test and flex the family to eliminate constraint errors. When you test frequently, it's easier to correct errors discovered during family authoring.

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Create and Constrain Geometry

Create a 3D shape by extruding a 2D profile. Video: Create an Extrusion	Create a 3D shape that changes along its length, blending from a starting shape to an ending shape. Video: Create a Blend	Create a 3D shape by sweeping a 2D profile around an axis. Video: Create a Revolve	Create a 3D shape by sweeping a 2D profile along a path. Video: Create a Sweep
Create a swept blend by defining 2 profiles and blending them together along a path. Video: Create a Swept Blend	Use void forms to cut the geometry of other 3D forms in the family. Video: Cut Geometry	Apply constraints to boundaries or faces of 3D forms to control the geometry with parameters. Constrain Family Geometry	Learn how automatic dimensions and constraints are applied to preserve the design intent of the family. About Automatic Sketch Dimensions
Flex the parameters and constraints to ensure the parametric family geometry behaves as intended. Test the Family

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Define and Use Parameters

Use parameters to track information associated with the family and to control family geometry. Create Family Parameters	Apply a parameter to a dimension in the family to control family geometry. Label Dimensions to Create Parameters	Use instance parameters to store information about each instance of the family placed in the project. Create Instance Parameters	Use formulas to create relationships between parameters in a family, to calculate values, and to control family geometry. Use Formulas in the Family Editor
Family types hold preset values for parameters in the family. Create multiple types for use when loading the family into the model. Create Family Types