A picture would be worth... well about 1k words.
You need to RTFM about automatically extending/joining roofs. If you get the hang of it, it's as easy in 2D as in 3D. I'd give you the exact page but am working in 12 at the moment. Good luck.
Nattering nabob of negativism
2023 MBP M2 Max 32GM. MaxOS-Current