Custom Windows in Revit: Step-by-Step Guide

This guide walks you through creating custom windows in Revit, from setting up the family file to loading it into your project. You’ll learn how to build a parametric window that adjusts to different widths and heights, complete with a sill, frame, and glass. No prior family creation experience is needed, but basic familiarity with the Revit interface helps.

What You’ll Need

• Revit (any recent version, 2020 or newer recommended)
• A project file to load the finished window into, or a blank project for testing
• Basic understanding of Revit’s ribbon and project browser

Step-by-Step

1. Start a new family. Go to File > New > Family. In the dialog, scroll to and select Metric Window.rft (or Imperial Window.rft if you work in imperial units). Click Open. This template already has the correct reference planes and host wall behavior set up.
2. Understand the template. You’ll see a floor plan, an elevation, and a section view. The dashed lines represent the host wall. The vertical reference planes labeled Width and the horizontal ones labeled Height are the primary parameters you’ll drive. The Default reference plane marks the exterior face of the wall.
3. Set up dimensions. In the Ref. Level floor plan, select the two vertical reference planes (one on each side of the opening). Click Dimension on the Annotate tab, then pick both planes. Select the new dimension, and on the Options Bar, click Label and choose Width (if it’s not already labeled). Do the same for the horizontal reference planes in the elevation view, labeling the dimension as Height.
4. Create the opening. In the floor plan, use Create > Opening > Vertical (or By Face). Trace a rectangle inside the wall’s reference planes, snapping to the Width and Height reference planes. Finish the sketch. This opening will cut the wall when the family is loaded into a project.
5. Add the frame. Switch to the exterior elevation view. Use Create > Sweep > Sweep. For the path, pick the inside edges of the opening (the four edges of the rectangle). For the profile, click Edit Profile and sketch a small rectangle (e.g., 2″ x 4″ or 50mm x 100mm) that represents the frame cross-section. The profile should be on the interior side of the path so the frame sits inside the opening. Finish both sketches. This creates a single sweep that wraps around the opening.
6. Add the glass. In the same elevation, use Create > Extrusion. Sketch a rectangle that fills the opening, slightly inset from the frame (e.g., 1/2″ or 12mm). Set the extrusion’s Start and End values (e.g., -1″ to 1″) so the glass is centered in the frame. Finish the sketch. Select the extrusion, and in Properties, set Material to Glass (or create a new material with a glass appearance).
7. Add a sill (optional). In the section view, create another extrusion for the sill. Sketch a rectangle below the opening, extending past the frame on both sides (e.g., 1″ beyond each side). Set the extrusion’s depth to match the wall thickness. Assign a material like Wood or Metal.
8. Lock and constrain. Select each extruded element (frame, glass, sill). Use Align (shortcut AL) to align its edges to the reference planes, then click the padlock icon to lock them. This ensures the geometry stretches when the width or height changes. For the frame sweep, its path is already locked to the opening edges, so it will follow automatically.
9. Test the parameters. In the Family Types dialog (on the Create tab), change the Width to 48″ (or 1200mm) and Height to 60″ (or 1500mm). Click Apply. Switch to a 3D view to verify the window stretches correctly and the frame remains intact. If anything breaks, undo the change and check your constraints.
10. Save and load. Save the family as MyCustomWindow.rfa. Then, in your project, go to Insert > Load Family, select the file, and click Open. The window will appear in the Windows category in the Project Browser.
11. Place the window. In your project, go to Architecture > Window. Choose MyCustomWindow from the Type Selector. Click on a wall to place it. Use the Space key to flip the window’s orientation if needed. Adjust its position using temporary dimensions.

Common Mistakes

• Not locking geometry to reference planes. If you just draw geometry without aligning and locking, it won’t flex with the parameters. Always use Align and lock.
• Using the wrong template. Starting from a generic model template instead of the window template means you’ll have to manually set up host behavior, which is complex. Always use Metric Window.rft.
• Forgetting to cut the opening. If the opening is not created, the wall will remain solid and the window will just float on the surface. The Opening tool is essential.
• Overcomplicating the frame. A single sweep is simpler and more robust than multiple extrusions. Avoid creating four separate frame pieces unless you need different profiles.
• Skipping the material assignment. Without materials, the window will render as a solid gray mass. Assign glass and frame materials before loading.

Tips

• Use symbolic lines. In plan view, add symbolic lines to represent the window swing or glass panes. These are 2D lines that only show in views, making your window look correct in plan.
• Add a sill height parameter. In the family, add a parameter for Sill Height (distance from floor to bottom of the window). This is a common requirement and can be done by adding a reference plane and dimension.
• Test with extreme values. Try setting width to 1″ or 1000″ to see if the geometry breaks. This helps you catch constraints that fail at extreme sizes.
• Use the Type Catalog. If you plan to have many sizes, create a type catalog (.txt) file so you can load multiple sizes at once.
• Keep it simple. Start with a basic rectangle. Add mullions, transoms, or arched tops only after the basic window works.

Troubleshooting

• Window doesn’t cut the wall. Make sure the opening was created with the Opening tool, not just an extrusion. Also check that the opening’s boundary is locked to reference planes that intersect the wall.
• Geometry doesn’t flex. Check that you locked all alignment constraints. Also ensure the dimensions are labeled to the correct parameters. If you see a warning about constraints, undo and redo the alignments.
• Window is upside down or mirrored. In the family, check the orientation of the Default reference plane. Use the Flip control (spacebar) when placing in the project.
• Frame is too thick or too thin. Edit the sweep profile and adjust the rectangle dimensions. Make sure the profile is on the correct side of the path (interior side).
• Glass overlaps the frame. In the elevation, select the glass extrusion and use Align to offset it from the frame edges. Or simply redraw the extrusion with a smaller rectangle.
• Family loads but doesn’t appear in the Type Selector. Check the category: it should be Windows. If it’s under Generic Models, you can change it in Family Category and Parameters.

Frequently Asked Questions

Q: Can I create a round or arched window?
A: Yes, but it’s more advanced. You’ll need to create a void extrusion or a sweep with a curved path. The same principles apply: use reference planes and lock geometry.

Q: How do I add a mullion (vertical divider) to my window?
A: Create a new extrusion or sweep for the mullion, and align it to a reference plane that you add in the center. Lock it, and it will stay centered when the width changes.

Q: Why does my window show as a solid mass in 3D?
A: You likely haven’t assigned materials. Select each part (frame, glass) and assign a material in the Properties palette. Glass needs a glass material with transparency.

Q: Can I make the window open (operable)?
A: Yes, but that’s complex. You’d need to create a nested family for the sash and use a rotation angle parameter. For most purposes, a fixed window is sufficient.

Q: How do I change the default size of the window when placing it?
A: In the family, go to Family Types and set the default values for Width and Height. Save and reload the family into your project.

Q: What if the window doesn’t show in plan view correctly?
A: Add symbolic lines in the plan view of the family. Use the Symbolic Line tool and draw the window’s outline and swing. These lines will display in the project’s plan views.

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