You can stack roofs on top of each other pretty much. So if you do a spiral, just place a roof on side and be sure you cover all building or you gona get rain damage and it will look ugly.

Only issue with circular buildings is there are no roof pieces to fill a very small gaps if you go over the circle, but inside can be easy filled. You can however stack 2 roofs from each side to fill the gap.

If you wana get a perfect angles, you can use wooden beams, angle them just a bit and place roofs on them.

Here is just a small example what you can make using totaly basic materials:
https://images2.imgbox.com/98/90/uekZGgYX_o.jpg
(ignore endgame gear)