So im trying to make a house tour game and i made a model in sketchup (not finsished yet) because it was not finished i tried and imort it to see if i did anything wrong. but when i imported it, it only showed one side of certain parts and other parts had the other side not showing
i have tried to put in a two sided material but that doesnt work 
Usually this has to do with the normals of your mesh. Not the material. I don’t know how sketchup works but you should check it’s manual to see if has any shortcut with the name " Make normals consistent" or so. Avoiding this problem i quite easy. I recommend you searching info about sketchup normals , since i don’t know how it works this is the only thing i can think of. Hope this helped!