Holes in slabs and Lift Shafts etc ......

If you need to create a similar hole in your slab on several levels ie. a shaft the tool to use is Opening --> Shaft Opening

You can define the bottom and top levels of the shaft in the Properties.

One of the big benefits though is that you can draw in some "Symbolic Lines" ie: a cross representing a hole in the slab.
These "Symbolic Lines" will then appear everywhere your shaft cuts through a slab.