Revit Trim/Extend: the 3 Trim Tools and Clicking the Part to Keep

Revit trim/extend tools shorten or extend an element to a boundary, or join two elements into a corner. According to Autodesk's help, they work on walls, lines, beams, braces and MEP elements such as pipes, ducts, conduits and cable trays (Autodesk: Trim and Extend Elements).

Revit 2027 has three Trim/Extend tools on the Modify tab. The difference from AutoCAD to remember: in Revit you click the part to keep, not the part to remove. This article covers each tool in Revit 2027, with Revit's exact prompts at every step. Trimming in AutoCAD is covered in the AutoCAD trim command; to learn Revit properly by discipline, see the Learn Revit course path.

The three Revit trim/extend tools on the Modify panel

The three tools sit on the Modify panel of the Modify tab, next to Split and Delete.

In the Keyboard Shortcuts dialog (type KS), only Trim/Extend to Corner has a default shortcut, TR. The other two have none; you can assign your own in the same dialog.

Assigning shortcuts is covered in Revit keyboard shortcuts.

Trim/Extend to Corner

1. Type TR, or click button 1 on the Modify panel.
2. The status bar prompts Select the first line or wall to trim/extend. (Click on the part you want to keep). Click the part of the first element you want to keep.
3. The prompt changes to Select the second line or wall to trim/extend. (Click on the part you want to keep). Hover over the second element: Revit draws a dashed preview of the corner.
4. Click the part of the second element to keep. The two elements join into a corner.
5. The tool stays active for the next pair. Press Esc to exit.

With two crossing walls, where you click decides what remains. Clicking the left half of the horizontal wall and the lower half of the vertical wall keeps those two parts and removes both overhangs.

Joining walls and changing join types are covered in walls in Revit.

Trim/Extend Single Element: one element to a boundary

This tool picks the boundary first and the element second.

1. Click button 2 on the Modify panel.
2. The prompt reads Select a reference as the trim/extend boundary. Click the boundary element. The boundary itself does not change.
3. The prompt reads Select a line or wall to trim/extend (Click on the part you want to keep). Ctrl-click to keep trimming to the current reference. Click the element to trim or extend, on the part to keep.
4. To take more elements to the same boundary, hold Ctrl while clicking, as the prompt in step 3 says.

Trim multiple elements in Revit

1. Click button 3 on the Modify panel.
2. The prompt reads Select a reference as the trim/extend boundary. Click the boundary element.
3. The prompt reads Draw a selection box around or click parts of elements to keep. Drag a selection box across the elements, starting on the side to keep, or click them one by one.
4. Release the mouse. The elements are extended or trimmed to the boundary.

The button's extended tooltip states the rule: the portions of the elements on the side of the boundary where you click, or where you start the selection box, are retained.

The example has three vertical walls and one horizontal boundary wall. Two short walls stop short of the boundary; the third crosses it. The selection box is started above the boundary.

One operation both extends and trims: the two short walls reach the boundary, and the third wall loses the part below it. Autodesk notes that a box drawn right to left only needs to touch elements, while a box drawn left to right must fully contain them.

Trim/Extend with pipes: Revit adds the elbow

Trim/Extend to Corner works on pipes. The example has two separate 150 mm pipes.

1. Open a plan that shows the pipes, such as L1 - Plumbing. Architectural plans often hide pipes above the cut plane.
2. Type TR and click the horizontal pipe on the part to keep.
3. Click the vertical pipe on the part to keep.
4. The horizontal pipe extends from 8000 to 10577.3 mm and the two pipes meet at a corner.

Window-selecting the corner and opening Filter shows three elements there: two pipes and one Pipe Fittings element. Revit has inserted an elbow, and the two pipes belong to the same system.

The elbow type comes from the pipe type's Routing Preferences; see pipe types in Revit. Drawing pipes is covered in pipes in Revit.

How the trim command in Revit differs from AutoCAD

People coming from AutoCAD often click the part to remove, and Revit deletes exactly the part they wanted. When that happens, press Ctrl+Z and click the other side.

Common mistakes

Frequently asked questions

Does the Revit trim command have a shortcut?

Yes, but only Trim/Extend to Corner: TR. Single Element and Multiple Elements have no default shortcut.

Does trim work on beams?

Yes. The Trim/Extend to Corner tooltip says it works on elements such as walls or beams.

Can I cut a segment out of the middle of a wall?

Not with Trim/Extend. According to Autodesk, use Split Element (SL), select Delete Inner Segment on the Options Bar and click two points: the inner segment is deleted and the rest is kept. Split with Gap leaves a gap between the two parts.

Does trimming pipes add an elbow?

Yes. Trim/Extend to Corner on two pipes creates a Pipe Fittings element at the corner, following the pipe type's Routing Preferences.

In short, Revit trim/extend is three tools with one rule: click the part to keep. TR makes corners, Single Element takes one element to a boundary, and Multiple Elements handles several at once.