Edit the floor boundary and use the align and trim tools to create a closed loop sketch.
Create a floor in revit.
Add a floor by picking walls to create the boundary.
If it is not active click modify create floor boundary tab draw panel pick walls.
Create you floors in the normal manner first.
As you place the cursor to create a level if the.
On the ribbon click level.
To sketch the profile of the floor click modify create floor boundary tab draw panel and select a sketching tool.
Once created select the floor element and then use the shape editing tools accordingly.
For type select a view type from the list or click edit type to modify an existing view type or create a new view type.
Open the section or elevation view to add levels to.
You can use shape editing tools to manipulate the surfaces of your floor elements.
Select one or more levels for which you want to create a plan view.
Architecture tabdatum panel level structure tabdatum panel level place the cursor in the drawing area and click.
Remove all shape edits to your surfaces by means of the reset shape tool.
Please like this video.
When performing the procedures you may notice minor differences in functionality and user interface.
The floor boundary must be a closed loop profile.