Venting exhaust fan

fotostatJuly 14, 2007

I just purchased a condo (haven't closed on it yet), there is no exhaust fan in the bathroom. There is an attic above the condo that I have access to, it is separated from the other units by a block firewall, I can do whatever I need to up there. Attic ventilation consists of perforated soffits and 2 passive vents (about 12" square) on the roof. I can't cut a hole in the side of the building or the roof, so I have to vent the bathroom exhaust fan some other way.

I purchased a Panasonic FV-11VQL4, I need a way to vent it.

From the little that I know, my only 2 options are to either let it just exhaust into the attic or bring the duct up to the passive vent and just let it exhaust near it. I wouldn't want to duct straight into the vent since it is needed for attic ventilation.

So what is recommended in this situation? Thanks!

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Can you vent through the soffit under the eave? Seems to me that a flush mounted grill under the eave would be unnoticable. Not that I'm suggesting that you violate any rules, but if you kind of installed it on the QT and painted it to match the underside of the eave, who would notice?

I really don't think you want to vent a bath exhaust fan into your attic. You're just asking for problems with damp and possibly mold. Mold scares really panic homeowners in condo buildings.

By the way, do you have an operable window in your bathroom? If not, your bathroom certainly wouldn't have been in conformance with the building code. Even with an operable window, most current building codes require bathrooms have an exhaust fan vented to the out of doors. Perhaps you could approach the problem with your condo association by advising them that you're trying to bring your unit into compliance with current building codes. It would be harder for them to argue with that.

    Bookmark   July 14, 2007 at 8:32PM
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Thanks for the reply!

There is a window in the shower, so I guess that is how they got by code.

I understand and agree about the moisture problem in the attic if I vent up there, but I figured it would be better to have the moisture up there than in the bathroom where it could cause more damage. But as I mentioned, I really don't know anything about the matter, just assumptions.

There is a sheetmetal soffit that I can get to from the attic, I wasn't aware that I would be able to vent out thru it. My only concern with that is the height, it would be nice if I could do the work from inside the attic vs. getting a large ladder and working from the outside.

    Bookmark   July 14, 2007 at 8:51PM
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Moisture or mold related problems would be far easier and cheaper to deal with in the bathroom than in the attic!

Find a way to vent to the out of doors, or do without the vent fan. You don't want damp in your attic!

    Bookmark   July 15, 2007 at 1:45AM
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Thanks again for the reply!

Out of curiosity, what type of damage would the bathroom exhaust do to the attic? Thanks!

    Bookmark   July 15, 2007 at 10:53AM
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If you live in a wood frame building with insulation in the attic, moisture is your worst enemy. It can lead to mold and mildew, rot, reduce the efffectiveness of insulation, and if you have composition or shingle roof, it could shorten the live of the roof.

Especially if you live somewhere with cold winters, steam released into the attic will condense, making for soggy insulation which can lead to all sorts of problems. Stained ceilings, rotten timbers, mold...the list goes on and on. YOU DON'T WANT TO GO THERE!

Thanks to the tort bar, if you ever have a mold problem, you'll have great difficulty obtaining insurance (insurance companies are terrified of mold claims), you'll need to disclose past mold problems if you ever want to sell (good luck on that one -- potential buyers hear the word mold and run!), and condo homeowner associations go into panic mode at the very hint of mold in thier buildings.

    Bookmark   July 15, 2007 at 12:20PM
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Sounds bad! I didn't know it would be like that.

So I am going to have to look into either venting thru the soffit like you mentioned, or petitioning the condo ass. to cut a vent into the roof.

On another note, how would I effect the efficiency of my condo if I vented the bathroom exhaust fan directly out of one of the 2 passive vents already cut into the roof?

Again, thanks for the info!

    Bookmark   July 15, 2007 at 12:42PM
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SO I found out that I can't vent out thru the roof or soffit. THe president of the association says that everyone just vents their fans into the attic. FWIW, the attic is condo association space, not my own, so any repairs wouldn't be my responsibility.

Knowing that I have no choice in the matter, would it be better to vent the exhaust fan out right by the passive roof vent? Or down towards the soffit (which is perforated with holes)?

    Bookmark   August 1, 2007 at 7:35PM
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    Bookmark   August 10, 2007 at 7:48PM
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I would stick the exhaust fan right at the passive vent.

And then I would send a certified signature return receipt letter to the association telling them what you are doing, and that you had to do it this way because they will not allow you to do it any other way. You may find this documentation helpful in the future if you get blamed for issues. Make it clear of the fact you WANTED to put a hole in the soffit and/or roof because this is proper construction standard, but they would not allow you to do this. I would also state that any issues this may cause are the responsibity of the association and not yours.

A letter like this may wake them up, and allow some changes to their rules. Again, protect yourself.

    Bookmark   August 11, 2007 at 11:06AM
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First of all, don't vent it out the soffit. The moist air will just get pulled right back into the attic thru the soffit vents. Obviously, many here are trying to have you avoid the attic all together, and if you agree, the soffit venting idea mitigates that.

Having said that, I'm not a "sky is falling" type when it comes to attic venting and mold. I presently live in a house built in 1954 and my master fan goes straight to the attic. Judging by the fans' construction and the jet plane noise it makes when I turn it on, it's been there since day one. There is not one hint of moisture or mold in that attic. I know the signs of mold, and there are zip, zero, zilch, nada...get the picture :)

Here's what I would do. Send the president of the association an email confirming his "...that's what everyone does..." statement. When he responds, print it out and throw it in a file you'll never lose. Now go ahead and vent that puppy straight up to the attic and forget about it. If the you know what ever hits the you know where, you simply pull out your never lose file and smile.

    Bookmark   August 13, 2007 at 4:10PM
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Thanks for the replies.

My Parents house is like yours, the exhaust fans from both bathrooms are vented directly into the attic and have been for at least 30 years, probably longer. No rot or mold of any kind.

    Bookmark   August 13, 2007 at 6:25PM
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