Cut an Opening in a Floor, Roof, or Ceiling
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.
Cut a Shaft Opening
Use the Shaft tool to place an opening that extends through the entire height of a building (or through selected levels), cutting through the faces of roofs, floors, or ceilings simultaneously.
Opening Instance Properties
Modify instance properties to change an opening's offsets, constraints, and more.