Creating a nested family in Revit allows you to combine multiple component families into a single, cohesive unit, enhancing flexibility, organization, and reusability in your projects. This powerful feature enables you to build complex elements from simpler parts, managing them as one family.
Understanding Nested Families
A nested family is essentially a family (the "host" or "parent" family) that contains one or more instances of other families (the "nested" or "child" families) loaded within it. This approach is highly beneficial for creating intricate components like furniture assemblies, window units with specific hardware, or complex mechanical equipment.
Benefits of Nesting Families:
- Modularity: Break down complex objects into smaller, manageable parts.
- Reusability: Create a library of standard sub-components that can be easily incorporated into various host families.
- Flexibility: Modify individual nested components without altering the entire host family, or control their visibility and parameters independently.
- Organization: Keep your project browser cleaner by having fewer top-level families, yet retaining detailed functionality.
- Parameter Control: Map parameters from nested families to the host family, allowing you to control nested components directly from the host family's properties.
Step-by-Step Guide to Creating a Nested Family
Follow these steps to effectively nest families within a host family in Revit:
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Open or Create the Host Family:
- Start by opening an existing family (.RFA file) that will serve as your host, or create a new family using an appropriate template (e.g., Generic Model.rft, Furniture.rft). This is where your nested components will reside.
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Load the Child Families:
- You need to load the families you intend to nest into your host family environment.
- From the Revit Family Editor, go to the Insert tab.
- Click on Load Family in the Load from Library panel.
- Navigate to the location of the .RFA files you want to nest, select them, and click Open. You can select multiple families by holding down the Ctrl key.
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Place the Nested Components:
- Once the child families are loaded into the host family, you can place instances of them.
- Go to the Create tab in the Family Editor.
- In the Model panel, click on Component.
- In the Type Selector dropdown menu located on the Properties palette, choose the specific type of the loaded family you wish to nest. This list will now include the families you just loaded.
- Click in the drawing area to place the nested component at your desired location within the host family. You can place multiple instances as needed.
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Position and Constrain:
- Use Revit's modification tools (Move, Rotate, Align) and dimensional constraints to precisely position the nested components relative to the host family's origin planes or other geometry.
- Align and lock nested components to reference planes or host geometry to ensure they behave predictably when the host family is flexed.
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Parameter Mapping (Optional but Recommended):
- To control the nested components from the host family, you can map their parameters.
- Select a nested component in the host family.
- In the Properties palette, click the small gray button (Associate Family Parameter) next to the parameter you want to map.
- Choose an existing parameter from the host family or create a new one. This links the nested component's parameter to the host family's parameter.
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Flex and Test:
- It's crucial to test your nested family by changing its parameters (if mapped) to ensure all nested components move and adjust as intended. This helps identify and fix any constraint issues.
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Save and Load into Project:
- Save your host family (.RFA file).
- Load the finished host family into your Revit project to use it.
Shared vs. Non-Shared Nested Families
A critical decision when nesting families is whether to make the nested components "shared" or "non-shared." This setting significantly impacts how the nested components behave in a project environment.
| Feature | Non-Shared Nested Family (Default) | Shared Nested Family |
|---|---|---|
| Visibility | Only the host family is visible and schedulable in the project. | Both the host family and the nested component are visible and schedulable independently in the project. |
| Scheduling | Nested components cannot be scheduled independently. | Nested components can be scheduled and tagged independently. |
| Tagging | Nested components cannot be tagged independently. | Nested components can be tagged independently. |
| Quantity Take-off | Only the host family's quantity is counted. | Quantities of nested components are counted separately. |
| Selection | Selecting the host family selects the entire assembly; nested components are not individually selectable. | Nested components can be selected individually within the project by tabbing through elements, or directly if unconstrained. |
| Use Case | Internal components that are integral to the host and don't need independent tracking (e.g., screws in a chair, a door handle within a door family). | Components that need to be tracked, scheduled, or tagged separately (e.g., light fixtures in a ceiling grid, chairs within a conference table family). |
To change the shared parameter:
- In the host family editor, select a nested component.
- In the Properties palette, click Edit Type.
- In the Type Properties dialog, check or uncheck the Shared parameter checkbox.
Practical Insights and Best Practices
- Keep it Simple: Avoid over-nesting. If a family becomes too complex with many layers of nesting, it can be difficult to manage and debug.
- Consistent Naming: Use clear and consistent naming conventions for both host and nested families to improve organization.
- Reference Planes are Key: Always use reference planes to define the origin and placement of nested components. Avoid placing them directly on geometry.
- Visibility Parameters: Utilize visibility parameters in the host family to control the display of nested components. For instance, you could have a chair family with an "Armrests On/Off" parameter that controls the visibility of nested armrest components.
- Family Category: Ensure your nested families have the correct family category for accurate scheduling and tagging in the project. If a shared nested family's category is incorrect, its scheduling behavior will be affected.
- Performance: While powerful, excessive use of overly complex nested families can sometimes impact model performance. Strive for efficiency in family creation.
By leveraging nested families effectively, you can significantly enhance your Revit workflow, creating more intelligent, adaptable, and data-rich building information models.
