Bathroom Exhaust

I was wondering if someone could enlighten me. In all that I've read about bathroom exhausts, most of the time it talks about using the soffit to exhaust the vapour.
However, I talked to a friend and he said to avoid that, because it builds moisture under the endge of the roof. I'd be better off with a roof vent.
Could someone please give me some feedback on this?
TIA
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I just replaced mine from a 50 cfm to 130 cfm vented it to the soffit where there was a vent, however before I did this I started to notice roofs in the neighborhood looking for roof vents, can't say that I seen any. Thats not saying that the soffit is the best.If the roof vent is best, there not that expensive, why are there not more of them out there.
When I re-roof I'll look where mine is vented to see if there is any mold or rot.
Tom

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The manufacturers of every bathroom exhaust fan I've seen, say they must be exhausted to the outside. You can go through the roof, wall or even soffet, and there are fittings for each application

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It is good practice to hide vents by putting them on roof at the back of the house, where they are more or less invisible from the street. This may (or may not) be why you can't see vents from the street.

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wrote:

Do you have existing roof vents? If so you can route your vent hose to the edge of an existing vent and staple it in place. This allows most of the exhaust to escape and still allows the roof vent to function as originally designed.
I assume this method is not to code but, I have used this method for more five years now without any moisture damage to any part of the vent area or the roof.
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wrote:

Whatta ya mean "not to code", it's up to mine. I've had mine that way for 4 years with no problems. RM~
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wrote:

I believe the code is that you have to have a separate vent exclusively used for the exhaust.
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MP wrote:

First never exhaust a bath vent to the soffit area. The natural air flow will keep it from going out the soffit and you will just build up moisture in your attic. Not good
I suggest you avoid venting it through the soffit. In this case since the natural flow of air is from the soffit to the higher roof vents it will tend to get sucked into the nearest soffit vent and cause the same problem, but to a lesser degree.
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Joseph Meehan

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If your neighborhood is like mine, most of the houses were built by the same developer around the same time. As such they all share certain details. In my case most single story houses vent through the roof as well as second story baths but first story baths vent through the wall. Some baths with windows have no vent at all.
I think the preferred method it to do whatever is easiest and still satisfy code which says the vent must be a certain distance from any window or door openings (this may also include soffit vent openings but I am not sure) and a certain distance from property line. (sorry I don't recall that distance). I believe back draft prevention device is also required (a flap)
Regardless of location, install vent pipe all the way to the outside.

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Thanks for all your input. I will most likely install a roof vent, doing it right the first time (unlike the "contractor" that did the extenstion on the house).

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Natual air flow??? What kind of air flow do you think you have coming from the soffits to the roof line? Wind tunner perhaps? Not.
Soffit vents are generally (I am saying generally from the ones I have seen) are a few feet apart. They are suppose to help with heat escaping in the summer and keeping the roof cold in the winter so water doesnt prematurely melt and create an ice backup. (ice dam)
That being said, putting a 6" hole in the soffit isnt going to disrupt anything. The forced air from the fan will blow the exhaust right out the vent. More or less a few feet away. The 'Natural Flow" of the soffit doesnt even come close to making a measureable vacume effect that would suck in the exhaust from the vent in the soffit.
One thing that can also bit people in the butt is that when venting moist warm air vertically, you increase the chance of condensation flowing back in from the vent. Lots of insulation would be advisable. (not sure if your in a warm climate or cold)
Horizon. runs you can pitch so that the flow wont come back.
Just a thought...
Tom
P.S.... I personally HATE putting holes in the room. More holes, more chance of water coming in. Over the years, the moisture from the showers and rust from the vent cause some crappy looking roofs too (stains)
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MP wrote:

about
to
builds
vent.
Here's one other possibility that I did: Our second floor bathroom happens to be directly under an attic dormer. I ran the fan exhaust a couple feet to the side to be directly under the dormer wall, and then up a few feet into the dormer wall. It vents out the side of the dormer wall. Seems to be the best combination to me, that the vent pipe rises continuously, and then vents out the wall with no roof penetration.
Ken
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why do you want a bathroom vent anyway...
in the winter, the humidity is good to keep in the house
in the summer, open the window
Mark
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Joseph Meehan wrote:

AND out the ridge vents, which you must have for all the reasons mentioned.

In winter especially the relative humidity of the vented air drops dramatically. Even in summer with humid outside air, if it isn't raining in your attic, the fan exhause won't start it.
Lots of insulation would be advisable. (not sure

I disagree. Insulation does not add heat. It is a barrier that prevents heat flow. Your insulation layer is what divides "inside" from "outside". Your attic should be outside so the insulation must be on/under the attic floor. That insulation will not affect far exhaust into the attic.
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snipped-for-privacy@gmail.com wrote:

Correct. They help because the cooler heavier air come IN through the soffit vents and the hot (lighter) air exits from the higher roof or gable end vents. The natural air flow is UP.

All the air that does go through the system is "sucked" up through the soffit vents. Where else do you think it is going to come from???

That I can generally agree with.

Of course you do need to provide somewhere for it to go. :-)

Good vents don't rust, but too much moisture does a great deal of damage to homes.
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William W. Plummer wrote:

And in-between it will leave moisture in the attic. Not good!

We are talking about a bathroom fan.

I believe you snipped a little too much and lost the context.
"One thing that can also bit people in the butt is that when venting moist warm air vertically, you increase the chance of condensation flowing back in from the vent. Lots of insulation would be advisable."
So it appears Bocestb was suggesting insulation around the duct to keep it warm (not add heat as it would already be warm) to reduce condensation.

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