Bathroom Exhaust Fan: Vent Through Wall or Roof? 0 Vote Up Vote Down phillie10 When installing a bath exhaust fan, is it better if the vent exits through an exterior wall or through a roof vent? Question Tags: bathroom remodelingThe Money Pit Answer Either is fine. What's important is that the fan vents outside, and not into your attic. Assuming all else is equal, let distance guide your desicion. The shorter the distance outside, the more efficient the ventilation process will be.