25/03/2026
How to Use Underlay in Revit Architecture to Show Cantilever on Ground Floor (Step-by-Step Guide)
If you want to clearly indicate a cantilever on your ground floor plan in Revit Architecture, one of the most effective tools you can use is the Underlay feature. This simple technique allows you to reference upper floors without wasting time or complicating your workflow.
In this guide, I will show you exactly how to use underlay in Revit to achieve this.
Step 1: Open Your Ground Floor Plan
To get started, go to your Ground Floor Plan.
Right now, you should be viewing the ground floor where you want to indicate the cantilever.
Step 2: Activate the Underlay Feature
Next, head over to the Properties Palette.
Scroll down until you find Underlay
You’ll notice it is set to None by default
Change it to First Floor
Click Apply
Once you do this, you will now be able to see the First Floor layout faintly displayed on your ground floor plan.
Step 3: Add Detail Lines to Trace the Cantilever
Now that the first floor is visible:
Use the Detail Line tool (Shortcut: DL)
Select the type of line you want to use
Choose the Overhead (dashed line) style
This dashed line is perfect for indicating elements above, like a cantilever.
Step 4: Trace the First Floor Layout
With the overhead line selected:
Click on Line
Carefully trace over the faint first floor elements (these represent the cantilever areas)
Ensure you are picking the faint lines (First Floor), not the bold ones (Ground Floor)
Once you are done:
Click on the Modify Tool
Step 5: Turn Off Underlay
Now that you’ve traced the necessary parts:
Go back to Underlay
Set it back to None
Click Apply
At this point, only the dashed lines you created will remain visible on the ground floor.
Step 6: Clean Up Using Extend Tool
To refine your drawing:
Use Extend Multiple
Remove unnecessary or excess parts of the lines
This helps you clean up the cantilever outline for a professional finish.
Final Result
Now, even while working on the ground floor, you can clearly see where your cantilever is positioned thanks to the overhead dashed lines.
Want to Learn More?
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