Revit Families: Loading, Editing, and Creating Parametric Components

What Is a Revit Family?

In Autodesk Revit, almost every object you place in a model — columns, doors, beams, fixtures — is a family. A family is a reusable, rule-driven component whose geometry and data are controlled by parameters. When you change a parameter value, the geometry updates automatically. This behavior is called parametric design, and it is one of the core ideas behind Building Information Modeling (BIM).

Revit organizes families into three types:

• System families are built into Revit and cannot be saved as separate files (walls, floors, roofs).
• Loadable families are created outside the project in the Family Editor and saved as `.rfa` files. You load them into any project that needs them.
• In-place families are modeled directly inside a project for one-off geometry.

This lesson focuses on loadable families, specifically building a parametric structural column.

The Family Editor

The Family Editor is a separate Revit environment you enter when you create or edit an `.rfa` file. Open it by going to File → New → Family and choosing a Family Template (`.rft`) file. Templates provide a starting environment appropriate to the category — a column template already knows a column sits between a base and top level.

For a structural column, select the Metric Column.rft template (or the imperial equivalent if your office uses feet and inches). The template opens with predefined reference planes and parameter stubs you will build on.

Reference Planes and Constraints

Before you sketch geometry, lay out reference planes. Reference planes are invisible guides that anchor dimensions and constraints. Best practice:

1. Place reference planes at each edge of the column cross-section.

2. Add parametric dimensions between opposite reference planes.

3. Label each dimension with a parameter (for example, `Width` and `Depth`).

When Revit sees a dimension labeled with a parameter, it locks the geometry to that measurement. If you later type a new value for `Width`, all sketch lines pinned to those reference planes move accordingly.

Instance vs. Type Parameters

When you create a parameter, Revit asks whether it is an Instance or Type parameter.

• A Type parameter is shared by every element that uses the same family type. Change it once and every instance in the project updates.
• An Instance parameter can differ from one placed element to the next. Each column can have its own `Width` and `Depth`.

For this exercise, use Instance parameters so that three columns placed in the project can carry three different cross-section sizes.

Building the Rectangular Extrusion

1. In the Family Editor, go to Create → Extrusion.

2. Sketch a closed rectangle using the Rectangle sketch tool. Snap the sketch lines to the reference planes you placed.

3. Set the extrusion depth to match the column height controlled by the template's built-in parameters.

4. Finish the sketch (green check mark).

5. Add dimensions between the reference planes: one horizontal (this will become `Width`) and one vertical (`Depth`).

6. Click each dimension, then click the small label icon that appears. In the dialog, choose Add parameter, name it `Width` (or `Depth`), set it to Instance, and confirm.

7. Repeat for the other dimension.

Flexing the Family

Flexing means testing the family by typing extreme or varied values into the parameters before you load it into a project. If the geometry updates cleanly with no errors or "cannot make constraints consistent" warnings, the family is robust.

In the Family Editor, open Family Types (on the Properties panel or the Create tab). Type a new number for `Width` — say, 400 mm — then click Apply. Watch the extrusion change. Try 150 mm. Try 600 mm. If the shape updates each time without warnings, you have built the constraints correctly. Fix any errors before loading.

Loading Into a Project

Once the family passes the flex test:

1. Go to File → Load into Project (while still in the Family Editor), or save the `.rfa` file and use Insert → Load Family from inside the project.

2. Place three instances of the column at different grid intersections using Structure → Column.

3. In each instance's Properties, type different `Width` and `Depth` values to confirm the instance parameters work independently.

Generating and Exporting a Schedule

A key BIM advantage is automatic schedules — tables that pull data directly from model elements.

1. Go to View → Schedules → Schedule/Quantities.

2. Choose Structural Columns as the category.

3. Add the fields: Family and Type, Width, Depth, and Count.

4. Click OK. Revit builds the table instantly from the live model data.

To export: go to File → Export → Reports → Schedule, choose a location, and save as a `.csv` file. Open the CSV in a spreadsheet program to confirm all three column entries appear with correct dimensions.

Workplace Safety Notes

The Family Editor is software-only work, but the general lab rules still apply. Follow your program's workstation ergonomics guidelines — adjust monitor height and chair position to avoid repetitive strain. Save your work frequently (Revit can crash during complex operations); use Ctrl+S every 10–15 minutes or enable Revit's journal-based backup. Never store project files solely on a local drive without a backup copy; loss of work affects team schedules in a real BIM environment. If you export files to a shared network drive, do not open or edit another student's family file without permission.