DIY Home Improvement Forum banner

Ok for a bathroom exhaust duct to go down and then back up?

813 Views 3 Replies 3 Participants Last post by  user_12345a
I am putting in a very small 1/2 bath in my finished basement. I am trying to figure out the best way to vent and exhaust fan to the outside. Unfortunately, the wall that butts up to the foundation does not have a window and it sits on the opposite side of my patio steps. Of course the joist run perpendicular to that wall as well. So I can run the duct via a straight shot between the two joists to the outside.

The best solution I can come up with is to have the duct run parallel to the joist to the foundation wall which is a 6" void between the foundation and studs. Then it would drop the few inches down and run parallel to the foundation before rising 10 inches vertically to pop out to the outside. I understand that dropping duct to raise it back up is not ideal because moisture can sit. Since there is no tub or shower, just a toilet and sink, would this be an appropriate solution to my situation? Any feedback would be great!


1 - 4 of 4 Posts

· Registered
6,508 Posts
If there's a shower in this bathroom, the vent will have moisture, and that could be no good for down and up vent.
Otherwise, it would be OK to offset the vent.
Try using solid pipes as opposed to flex.

· Registered
17,654 Posts
Solid metal is far less restrictive to airflow at a given pipe size than flex.

So you get more airflow at a higher velocity which reduces the risk of condensation from forming.

Insulation on the exhaust pipe is not required when the run it short enough and it's inside the house. Still a good idea.

Having the pipe turn down after going up won't cause problems provided condensation doesn't form in the first place.

Condensation forming in the pipe is the problem, not moisture in itself.

Be sure to put this fan on a timer and instruct everyone to run 10 minutes after showering/bathing so the moisture gets cleared out before the fan shuts off.
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.