Hi, I've done the backface culling in viewport mode in order to not see the wall but when i go in render mode, I don't have the option and we don't see the interior of the room because the wall don't disapear. Thank you for helping.
Hey ddarkrikou, there is no backface culling in rendered view - you'll have to make those walls separate objects and turn them off for the Camera in the object properties. I mention it briefly here: https://cgcookie.com/exercise/modeling-a-low-poly-room?wtime=101
That should do the trick!