My master bathroom is wired for a fan, but I opened it up and found that it is just venting into the joist between the ceiling and the second floor.

There are no exterior walls to access in the bathroom. Also the joist runs to the main house in one direction, and to a back room in the other.

The back room has the end of a hip roof over it, but I don't think there is any access into the roof section.

So I think the only option would be to bring a vent down the joist, through the wall into ceiling of the back room and out through the roof. Is something like this possible without completely cutting up the ceilings and the roof?

I'll probably have a pro look at it, but how much would something like this cost?

  • Do you have a window in the room? How long was old fan there? Is there a shower? – DMoore Feb 20 '14 at 15:40
  • Can you run a flex vent through the joist to the hip roof room? If so, can you vent it out at that exterior wall? – Ethereal Feb 20 '14 at 15:41
  • @Dmoore, there is no exterior wall, hence there is no window. – cmcginty Feb 22 '14 at 1:59
  • @ethereal, yes, I think that could work to. Is the exterior wall better than going to the roof? The roof is probably a short distance. – cmcginty Feb 22 '14 at 2:02
  • @Casey I do believe going through the wall is the better choice -- you don't want to compromise your roof if you don't have to, and the roof overhang will prevent water from entering the vent. It will look better also. – Ethereal Feb 25 '14 at 13:45

Without seeing the house I cant tell you. It sounds like you are talking about creating a soffit which is going to be alot of labor.

You have some other options. If this is just a 1/2 bath you can but a vent-free vent that uses a charcoal filter for smells. If there is a bath then you can get a small dehumidifier.

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  • Thanks, this is actually our master bath so it gets the most use. That is why I really think it needs a full vent. – cmcginty Feb 22 '14 at 1:58

I just confirmed with inspector for my use case - with forced air (fan) I can route down to route through floor joists. Exit can be on side of house if a) more than 10' from a window and b) not in a walkway.

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