Use the Sweep tool to add a baseboard, crown molding, or other type of decorative horizontal or vertical projection to a wall. 
 Video: Add a Wall Sweep 
-  Open a 3D or elevation view containing the wall to which you want to add the sweep. 
 
- Click Architecture tab
Build panel
Wall drop-down
 (Wall: Sweep). 
 
- In the Type Selector, select the desired type of wall sweep. 
 
- Click Modify | Place Wall Sweep
Placement panel, and select the orientation of the wall sweep: Horizontal or Vertical. 
 
-  If you are adding a sweep to a 
  slanted wall, on the Properties palette, for Orientation, select Perpendicular to Face or Parallel to Ground. When changing a vertical wall that contains wall sweeps to a slanted wall, the sweeps will remain in a vertical orientation and you must adjust their orientation manually using the Orientation Instance property. 
 
- Place the cursor over the wall to highlight the wall sweep location. Click to place the wall sweep. 
 
- Add the wall sweep to adjacent walls, if needed. 
  
Revit preselects the wall sweep location on each adjacent wall. 
  
 
  If you are in a 3D view, you can add a wall sweep to all exterior walls by using the ViewCube to rotate the view. 
  
 
 
- To start a wall sweep in a different location, click Modify | Place Wall Sweep tab
Placement panel
 Wall Sweep Restart. Move the cursor to the desired location on the wall, and click to place the wall sweep. 
 
- To finish placing wall sweeps, click Modify.