What's the deal with roofs and half walls?

    Today, since I am creating a very specific design, I decided to try adding half walls to my building. I removed all of my previous roofs (it didn't look right), and added some shorter walls to the second story of my house. It looked good, so I tried placing the roof. Oddly, you can't actually place a roof on a half wall, even though there's a grid above it. Instead, it floats! The roof floats! I don't understand this. Realistically, there can't be a floating roof. There are houses in real life built with both tall and short walls, and the roofs all look "normal" (which is what I am trying to create in The Sims 4). It did surprise me to know that, even though half walls are technically "real" walls, the placement of all roofs are set as if they are on FULL sized walls. Why is that? It's great that we have shorter walls to work with, but they're not much use to me if I can't use them with roofs... It's just that one minor "bug" (for lack of a better word), that's going to bother me so much. Half walls would be absolutely perfect for my house! I just... can't place them under roofs. Can someone please explain to me the logic behind this? Are short walls made just for the use of indoor housing? I sure hope not.