this was a HUGE pain to do, and it took forever... but this is what i figured out... i am currently working on an appartment. is there a tutorial for this?

one thing that is kinda sad is that i can't do windows or anything on the upper part of the lower level.





the stuff outside the house was a "just in case" so i had the elevations.

Use foundations

The way you've done it, the wall above the bottom floor has ended up being stretched to be equal with the elevation of the "second" floor. Technically the game reads it as one wall so you can only put one set of windows in.

I don't know why you've made the terrain like you have but if you want to do a basement etc, do it within a foundation and build on top of that. It'll give you more freedom to switch up the levels and stuff.

I'm not hugely adept at building so perhaps a pro can come by and give you some more direction Good luck!

This really got me thinking...
I decided to try and recreate something that bares a resemblance to what you made, and came up with this. (sorry, you'll have to download image)
It is something i threw together in the space of about 40 minutes, and am more than happy to try to refine it if you are interested, and then post you description of what needs done. Note that refining it WILL take time, and if you find another way, that is fine