Fog Of War/ Visibility

Hi everyone first of all thanks to everybody in this forum, since I began using UNITY I have been reading quite a few post in here to get my bearings and have found everyone very friendly and helpful but now I need to ask a simple question.

The thing is I did a tutorial to implement Fog Of War using a shader and it work's pretty well (Tutorial link: https://www.youtube.com/watch?v=yzcfTb9e0lo), but since I have building's and other stuff on the scene I want to make sure that if the player is outside of the building the fog of war would still be obscuring the insides of the building until the player gets inside, is there anyway I can implement this with a shader or anything else??

Any suggestion will be really appreciated. Thank you.