Where should you vent a bath fan?

Bath fans, or bathroom fans, are important pieces of equipment to remove moisture from your attic. Not long ago we watched a video online that was nicely edited - and the host spoke with confidence on how to vent the bathroom fan to the outside. In the first 30 seconds, he told us 3 wrong ways of doing it, thought he was convinced he was doing it right. Make sure you make the right choice for your home.

Why vent the bathroom fan to the outside? 

  • You want to remove moisture from your home. 
  • Taking hot showers can put a lot of moisture in your home. If the moisture is not removed properly from the home, you may have a mold problem on your hands. 

What happens if you do not vent the fan properly?

  • Strong likelihood of mold! Look below, the bath fan is vented to the soffit (not the way to do it)

The bath fan is located in the center cavity just below the eave chute. When a bathroom fan is vented into the soffit, it puts the moist are outside. Many contractors do this as it's easy and they do not have the proper knowledge. Then, due to how the attic ventilates, the moist air reenters the home right through the eave chute. As you can see on the other cavities, no mold / moisture problems!

What are the best practices of venting the bath fan to the outside, and why?

  • Vent to the outside - put the duct through the roof, air seal, install roof cap on the roof, and use tar to seal down shingles
  • Use rigid duct, not flex duct
  • Do not vent into the soffit nor in the attic
  • Use duct wrap insulation to insulate the ducting. This prevents chances of condensation in the winter