Larian Studios Forums Divinity: Original Sin 2 - The Modding Dungeon Divinity - Original Sin 2 - Modding General Unable to Add Floors

So is there a way to fill an entire roof for a larger building, or is that a camera block trick? Didn't realize that was going to be an issue until I couldn't figure out a way to close the roof I started:

https://cdn.discordapp.com/attachments/169758353663197185/368866645785182228/unknown.png