The primary means that moisture moves is by convection. Warmer air can carry more moister than cooler air. When warm air comes in contact with a cool surface it starts cooling, loosing its ability to hold as much moisture as it was able to do when it was warmer. When it reaches it's dewpoint, the point where it can no longer hold the amount of moister is has, condensation occurs.
The usual measure used to control moister movement is by a vapor barrier. But a vapor barrier's function is to stop conductive moister movement, preventing or limiting moister from passing through it. Unless measures are taken to eliminate air movement, the warm moist air will go around the vapor barrier.
To eliminate condensation as you have discribed, one needs to create an air movement barrier.