Use one of the Opening tools to cut a vertical or perpendicular opening in a roof, floor, or ceiling (for example, to accommodate a chimney). You can cut openings in the faces of these elements, or you can select the entire element to make a vertical cut.
 By Face or
 By Face or 
   Vertical.
 Vertical. 
  Where is it?
 Opening panel
Opening panel 
	  Opening panel
Opening panel 
	 Use the By Face option when you want the opening to be perpendicular to the selected face. Use the Vertical option when you want the opening to be perpendicular to a level.
Revit enters sketch mode, where you can create an opening of any shape.
