Someone tell me it's OK to vent a bathroom fan into the attic!

[steronz]

I know it's wrong, but the internet won't tell me what I want to hear! Internet, you're full of so many wonderful things, why can't you just humor me?

[campp]

It's wrong to vent a bathroom vent into an attic.

There.

[aerodave]

I can say that the bathroom fan in our house vented directly into the attic for an indeterminate amount of time, but probably at least 15 years. Nothing bad happened.

But that doesn't make it right.

[Ludy]

Sure, go for it, vent into the attic. Then you can have your very own attic sized mold garden. You can go up every few months and see what new colors are growing. It's like a science experiment. Fun for the whole family.:D


Or, not. Your choice.

[steronz]

<crawls into corner, wimpers>

[engineer_comp_geek]

If you live someplace that is dry enough (like say Arizona) then it is actually OK to vent the bathroom fan into the attic. In someplace more humid like Louisiana though, not so much (unless of course you are into the aforementioned science experiments).

[carnivorousplant]

Once you get the vent into the attic, it shouldn't be terribly difficult to run the pipe to the eaves or a side wall.

[johnpost]

in many situations it is a bad idea.

if your attic gets cold in a winter climate the moisture will freeze in the attic and not leave it, then when the weather warms you will have lots of liquid water in your attic which will cause rot and mold.

if you are in the hot dry desert it might be done without harm.

[Yllaria]

Isn't that what those accordian pipes are for?

(It's the internet, so no one can see that my bathroom fan goes into the attic. Of course, that's the least of this house's problems.)

[steronz]

I just replaced the fan to finish up a remodel. It's been venting into the attic for the last 30 years (not my doing, obviously). I'm not looking forward to cutting a hole in the roof in December is all.

[John Mace]

I just replaced the fan to finish up a remodel. It's been venting into the attic for the last 30 years (not my doing, obviously). I'm not looking forward to cutting a hole in the roof in December is all.

Wait until spring. Thirty years vs Thirty years + 4 months isn't really a difference. But just make sure you do it.

Alternatively, hire someone. It shouldn't be more than a few hundred bucks.

[johnpost]

I just replaced the fan to finish up a remodel. It's been venting into the attic for the last 30 years (not my doing, obviously). I'm not looking forward to cutting a hole in the roof in December is all.

another winter won't likely matter.

you want to plan and do the job right. you want to get rid of all the moisture and little heat (if you are in a heating climate).

making as few holes through the roof as possible is good. venting through a gable wall is good though you want it to be mostly downhill and might need rigid pipe.

[corkboard]

The right thing to do is to vent it outside, which is what I've done for (counts...) four bathroom renovations. However, those were all full baths and had a shower/tub.

When I renovated my powder room last year, I vented it into the attic. It might not be right, but I can justify it.
1) There's no humid air in the bathroom because there is no shower in there.
2) The real purpose of this particular vent fan is to mask bathroom sounds (we purposely got a noisy one), since it's on the other side of one of the kitchen walls.
3) The house is fairly dry.
4) Probably 95% of the time the powder room is used, it's for a quick pee and hand wash; I'm the only one in our family who uses it for more serious business, during which I turn on the fan (it's on a separate switch from the light).
5) There's probably more likelihood that the attic will be affected by the humid summer air than what little house air I send in there.
6) Cutting into the ceiling/roof or sidewall was going to be a huge pain in the ass because of the location of the fan and slope of the roof.

I'll report back in 30 years if it causes a mold problem by then.

[Implicit]

Since you'll be cutting into the roof when you do move the bathroom vent, you might want to consider adding some additional attic vents at the same time. More venting is recommended now than was 30 years ago.

[johnpost]

The right thing to do is to vent it outside, which is what I've done for (counts...) four bathroom renovations. However, those were all full baths and had a shower/tub.

When I renovated my powder room last year, I vented it into the attic. It might not be right, but I can justify it.


4) Probably 95% of the time the powder room is used, it's for a quick pee and hand wash; I'm the only one in our family who uses it for more serious business, during which I turn on the fan (it's on a separate switch from the light).


they do get called fart fans for that application.

[Pai325]

When we sold a house 25 years ago, the inspector noted on his report that the bathrooms were vented into the attic, and we had to change the venting for the buyer. When my daughter bought a house two years ago, her inspector noted that the bathrooms vented into the attic, and they had to fix it. You may as well vent it correctly now.

[Smeghead]

T
I'll report back in 30 years if it causes a mold problem by then.

It would fill my heart with joy to see an update come through in 30 years.

[flight]

I am not sure it holds in all areas, but code here is that you only need fans if there are no openable windows. If you have an openable window, you can eliminate the fan.

[corkboard]

It would fill my heart with joy to see an update come through in 30 years.

You're on! (provided I'm not so feebleminded then that I can't type, or think, or... what was I going to do again? [wanders off, sniffing the wallpaper])

[RTFirefly]

I am not sure it holds in all areas, but code here is that you only need fans if there are no openable windows. If you have an openable window, you can eliminate the fan.Even if a fan isn't required by code, it's still pretty desirable at times of year when you don't want to let the outside air in. If I'm taking a shower and it's 20 degrees outside, I want the humidity being vented to the outside by a fan, not via an open window.

[DMark]

[QUOTE=engineer_comp_geek;14514136]If you live someplace that is dry enough (like say Arizona) then it is actually OK to vent the bathroom fan into the attic.QUOTE]

I live in Las Vegas and we have practically zip humidity year round. That said, mold is a HUGE issue in homes here. I briefly worked for a law firm, and I have seen horrific photos of mold growing in the walls and ceilings of homes in this arid part of the country.
People get really sick and don't even know mold has been the cause.
Good for the lawyers, bad for the schmucks who didn't think mold grews in low humidty areas.

[Dewey Finn]

2) The real purpose of this particular vent fan is to mask bathroom sounds (we purposely got a noisy one), since it's on the other side of one of the kitchen walls.
If I ever build or remodel my own house, I want to insulate the bathroom walls just for that reason, particularly if it's one of those powder rooms just off the living room or foyer. And when I visit friends, I usually try to use the upstairs bathrooms just for that reason. I had one friend who had a powder room adjacent to the kitchen with a louvered door. There was no way that I wanted to use that for anything that would make noises.

[Ruby]

I can't speak for other climates, but here in the midwest, venting to the attic is baaaaad and I think even against building code. Even a low number of roof vents can literally destroy a roof from moisture/condensation. I agree that 4 months shouldn't make a big difference but remember, this is a new fan. If the old fan was indeed 30 years old, it may not have been venting that much anyway. So now you have a new fan that is actually working properly and you have much more moisture going into the attic space.

ETA: Insulation in interior walls is an amazing invention to me. My son used to host computer parties with 10+ 14-year-old boys and with the doors closed we could barely hear them in the next room.

[Magiver]

Sure, go for it, vent into the attic. Then you can have your very own attic sized mold garden. You can go up every few months and see what new colors are growing. It's like a science experiment. Fun for the whole family.:D


Or, not. Your choice. I tried to move the vent to the roof but a government agent said it would kill of an endangered species of mold so I was forbidden to do it.

Seriously, 80 year old house, Vented bathroom fan into a poorly insulated attic and no mold. And I have side gable vents that should make it worse. I have the ultimate mold factory looking for clients.

I suspect it's because there aren't enough people using the bathroom to create the problem. Frankly, it's really easy to add a roof vent although this isn't the best time of year to do it.

[FlyByNight512]

If I were in your shoes I'd wait until spring, since another four months of venting to the attic seems minor compared to the trouble I could get into trying to cut a hole in the roof in the middle of winter. Knowing my luck, I'd install something wrong, and then be trying to fix a leaky roof during the winter...

[johnpost]

there are insulation materials that claim to be optimized for sound deadening in interior walls if that is a purpose. i haven't used or priced or compared to thermal insulation.