Flat roof?

I built a 3rd floor directly on top of the 2nd floor (same exact size and shape). Then replaced the 3rd floor walls with fencing (was unable to just place fencing without wall ? Will have to experiment with this more). This is my very first sims 4 build so it's a learning experience.

That gave me a flat roof on top of the 2nd floor surrounded by a fence. In Willow Creek a lot of the houses have roofs like this.

But I noticed it actually created a 3rd floor, the game considered it a 3rd floor. And from world view you could SEE a weird floating 3rd floor flat roof. I remembered reading in a different thread that I can't seem to find now something about the sledgehammer tool! I sledgehammered the 3rd floating roof! Thank goodness.

I've been entering the other pre-made houses to look at their roofs and sure enough it looks like it was made the same way!

I am however, concerned IF seasons EP were added, would this "roof" keep the rain and snow out???