Making objects impenetrable

I’m currently at a problem similar to this one :

I want to re-create a room with accurate measurements (yes, Nomad probably is not the first choice for architectural design, but sitting on the couch using my tablet always trumps any dedicated program for my PC). It is hard to place object very accurately, since there is no “snap to object”-option or something similar. I figured, I can place the pivot at the bottom of an object and then press “Move origin” in the gizmo menu in order to place all objects at the same height. But this is limited to vertical placement.

My question is, whether or not it would be possible to mark objects as impenetrable. I’m not talking about a rigid body physics simulation. Just an option that would forbid any other object to intersect with the marked object.
Once a marked object is being hit, no further translation, rotation or scaling is possible. Creating a new primitive where a marked object sits would “simply” be responded with an error message.
Also it would be fine, if only one object could be marked at any given time. While this would cause some heavy “on/off tapping” between different objects, it still would allow to place all objects in an easier way.

Sounds like hard work. For furniture place pivot at bottom of object, in pivot settings, and then use ttansform tool to snap it to the surface of the floor.