Re: Can't finish building second floor on Sims 4
Ok, thanks for the pic. You're not too high so that's not it.
So, try this. Use the Custom Wall Tool to redraw all the walls on the second floor. On the second floor, just start at one corner and trace over the walls from corner to corner until you are back to where you started. It'll wipe out any wall paint but that's easy to fix. After doing that, you should be able to place floor tile.
If you still can't do it at that point, then drop down a level and select a room, go back up a level and click on the yellow outline around the top of the room below. If it says build ceiling, then click on the message to build a ceiling. Do that for all the rooms below. Then try to place floor tile on the second floor. That should work and let you place the floor.
Hope this helps.