The Curtain Wall is placed on or relative to the input plane.
•In the Floor Plan, the input plane is the Story level.
•In Section/Elevation/IE, the input plane is identical to the Section plane.
•In 3D, the default input plane for Curtain Walls (as for any construction element) is Project Zero or the User Origin, but you may use several methods for defining any other input plane.
See Curtain Wall Input Plane in 3D Window.
Create Curtain Wall on the Floor Plan
Draw Curtain Wall Boundary in the Section Window
Create a Curved Curtain Wall: Geometry Methods
Positioning Curtain Wall in Section
Curtain Wall Input Plane in 3D Window