What if I want to make props for the roof?
Then you can't. Your only other option is using a floating mod like I use, but that breaks the following game functionality:
1. Wands break a single brick
2. Hammer doesn't work on connected bricks
3. Undo only affects painting/printing
4. Duplication does not work
I recommend just using cubes for your modter "zones" and having the detailed areas above the cubes.