So! In the new 2.8 update, the defaults are such that if you extrude faces you might get a weird glitch where some faces are transparent (you'll know it when you see it)- it's a super easy fix, though! Open material properties, go to "Settings" and check "Backface Culling"- that'll fix it right up!

Also!  To find "CORRECT UVS"- since folks have been having some trouble- you have to make an edge loop first, and an adaptive menu appears in the lower left of the viewport giving you more options. You might have to click on an arrow to expand it.

Honestly I should have done this one a while ago. I've used it literally a hundred times. The best part is, once you have a building, you can use it over and over in different projects.

If you feel like watching the uncut screen capture, it's here. It's also boring: https://youtu.be/KBBeSHJlfRo

download blender at Blender.org

https://www.patreon.com/IanHubert