I have a question about environment walls, I am creating some modular sci-fi assets, and wanting to know do I add some thickness to the wall i.e cube or use a planes in the 3d application?
Depends on how you want to use the assets. You can do it just with planes, but then you have to keep in mind that you wont have a backface -> so when you look from the other side you will see through the mesh + it wont cast a shadow when the invisible side is facing the sun (you will have to add a two sided material). The only advantage is, that you save some tris and a little bit of work 
Okay Thanks! I saw that would be a problem in the future, so i’ll redo all of my assets. I wanted to save some Tris, but it’ll only be small amount of tris so i can bare down on it and just eat the tris.