Light reflections pass through walls

Hey,

I'm trying to create something very similar to that game: http://www.oneonlinegames.com/games/spy-games/spying-around but like a closed-museum-at-2am scene. So there's very dark floor, night (no directional light), walls and guards walking around with spotlights. The main problem I'm facing are light reflections:

1) if I set floor's material to specular, reflections (even light if it's high enough) pass through walls (https://www.dropbox.com/s/ok9uf96jgrm7xo9/Screenshot%202015-10-12%2012.44.01.png?dl=0, example taken from the real project)

2) if I set floor's material to standard, lights don't pass through walls but also the floor isn't enlightened

I also tried with different objects on the other side of each wall (for culling layers) and floor's material set to specular but that's not good idea since the other guards then enlighted that objects and they either have extremely hard shadows (because of culling) or those objects are visible (hardly visible, but still).

Any idea how to solve that would be great and if it's possible - the solution should be part of Unity 5 free version.

Thanks in advance, B.