After we created our simple two rooms in previous tutorials, which can be found here. I double the speed of the video and build the rest of the environment.
This is more of a workflow tutorial rather then how to. It will show you how I go about blocking in the interior space of the environment and how I expand into exterior.
Video is double the speed and with a voice-over to explain how I am working.
L4D Mapping: Environment Creation Part 1 - Video Tutorial