“This is an unfortunate side-effect of how static indirect lighting is handled at the moment and doesn’t have an easy way to fix.”
That’s helpful 
I’ll try some of the tips listed there, but at this point I think I bet on a wrong horse going into mobile development.
[MENTION=4894]Tim Hobson[/MENTION]
It’s not about shading differences between modular pieces. Floor is a single static mesh. It’s about lightmapper ignoring 100% sealed off space and not calculating lighting properly for indoor areas located in the outdoor areas.