Why isn’t this building collapsing?

Ok, after some try and error research I did myself in my base I figured out, in the first base there is a soccer field right behind the Hills in the back of the base. This soccer field has a zone around it which doesnt let you build 3 tiles around it and 5 tiles under and above it.

This zone is apparently considered as constructions (or what ever the physic does behind the scene) so if buildings are in direct contact to the zone you can't build in, they seem to be considered as beeing attatched to something solid, and wont collapse therefor.

So everyone who dreamt of having a flying castle in his base, just attatch its "base" to that zone ;)