To avoid the automatic cut-out of holes over a staircase:
- Select the staircase,
- Export selection as .obj.
- Import the .obj file without selecting the Staircase option.
- Draw the room on the floor above manually (to create a hole for the stairs).

Of course, there are more elaborate ways of approaching this, see the SVG Mini Manual for more.

See also thread,5478 (in FR - sort of ...).

ok

BTW:
Make sure you leave enough headroom between the steps and the ceiling in the staircase. Not only is this a legal requirement many places, but banging your head in the ceiling above a staircase can hurt, badly. Grew up in an old house made for the vertically challenged. Permanent bump in the head.