Re: I can’t put floors upstairs

Has the process of building upstairs created a room? If it has you should be able to select the room and a yellow border appears at the bottom. You should be able to click that and "build floor". If building hasn't created a room upstairs, try retracing your wall lines until it does. It should automatically build the floor once it recognises a room.

You need to "build floor" before you can place floor tiles.