When creating buildings, after some time i always end up with this bug..
Basically, if you highlight your geometry in the polygon selection, the selected parts turn yellow, right? But.. Some parts turn blue and when you extrude the selected geometry (containing both yellow and blue parts) The blue and yellow parts go opposite directions..
Sooo, how do i go around this?
The yellow/orange color means that you're looking at the "outside" of a surface while the blue means it's the "inside."
You can switch the orientation of the surface using the Reverse Normals command the shortcut is U-R (tap u then tap r). You can also align normals with U-A. Generally I'll run align normals on all polygons first then reverse if necessary.