???
No result is the same : roof or not roof :)
Select as on the image !
The door will made a hole :)

Thanks Michael,

you are really superfast in answering :-)
I understood your explanations, and I will make some more experiments with the different methods. I am quite a novice in NURBS modelling, but now that I found a tool so nice to use as MoI, I plan to learn and improve my skills.

Ciao

Antonino

Hi Pilou,

Sincerely I did not understand your message (and the figure). I tried several times, so I am quite sure to have selected the room as base object and the door as object to subtract. Could you please explain better your results?

Ciao

Antonino

in my example there no floor so that works :)