Fog Volume Issue

I’m currently mapping in Left 4 Dead 2, and I have this really annoying issue. You see, the desired effect is that when the player leaves a building, the fog is meant to change from interior to exterior fog in the hallway leading up the the exit. However, in game, the fog doesn’t cut in until the player is a fair distance from the building. Even more annoying is that when the player walks back towards that edge of the map, the interior fog kicks in again. In both cases, the transition is about 100 hammer units AWAY from the fog_volume brush, and it keeps re-occuring.

Does anyone know of a way to fix this?
Things that do not work:

  • Simply changing the shape of the brush doesn’t work
  • Breaking the brush up into smaller brushes and rearranging them so that they’re nowhere near the faulty transition point doesn’t work.
  • Changing the placement of the fog_volume brushes so that they are 100 units away from where I want them to doesn’t work.