# Snow in through Bathroom Exhaust Vents



## RedRiver

We live in a three-year-old home in Fargo, ND. We have four bathroom exhaust fans that vent through our roof. Each of them, to some degree, "chatter" and clatter when the wind blows. Even more of a problem is that snow blows in during periods of heavy snow/wind, eventually blocking the duct and/or fan itself. This does not appear to be condensation building up on an inadequately insulated duct. The ducts appear to be properly insulated and installed. When I remove the interior fan cover, one can readily see snow packed in around the fan which ultimately melts and drips down in the bathrooms and damages the ceiling sheetrock. Is my theory of snow infiltration rationale? Does anyone have a recommended solution? Can one purchase some sort of roof vent cover that provides some resistance to opening so it isn't so easily and improperly opened by wind?


----------



## jaros bros.

You should combine all of those vents into one. The motor gets mounted up in the attic. Fantech is the company to check into. A spring loaded vent would help prevent the wind from moving the flappers so easily. The ones you have right now are not spring loaded if they're the ones I've seen before. I think they just close with gravity.


----------



## creamaster

I just installed a bathroom fan and used this same vent cap. It hasnt snowed here yet but I will update this thread if I notice any problems with mine. My cap is on the south side of the house so I am hoping I dont get any snow blown into mine. Looking at your pics I am curious why the shingles are not covering the flashing of the vents. If the caulking fails you will likely end up with water leaking in through the nail holes.


----------



## Lazy_Jake

That seems like a bad set-up for your region. You wont see that type of vent here in Maine. Vents here are done either through the underside of the overhangs (soffit) or just below the overhangs on the exterior wall. 

I guarantee if you re-route the vents to the under sides of your over hangs and install sprung vents, you wont have any of these problems again.


----------



## BamBamm5144

Yikes, who roofed that?


----------



## buletbob

That's what happens when they go to roofing classes at Home Depot. Not saying the poster did it . I see it all the time.Pure laziness. (Butcher)
They should be under the shingle. Also the first pic, looks as tho the vent is distorted. The flapper could be hung Up.


----------



## jaros bros.

They don't like to run the vents under the soffits because a lot of the moisture can easily get sucked back into the attic.


----------



## RedRiver

*Great Observations!*

I appreciate the observations and suggestions. This should help as I communicate with a contractor to fix this. I'd like to fix it myself but I'm out of ideas. I replied to a ServiceMagic popup on this site and already got a local contractor to inquire.


----------



## skymaster

Whoever installed those vent caps should be taken out back and strung up with barbed wire!!!!!!!!!!!!! That is SOOOOOOOOOOOO BAAAAAAAAD
it even gives BAAAAAAAAAD a bad rap. :yes::yes:


----------



## jogr

As the others have said the vents were installed wrong. The shingles should lap over the vent flanges so that only the lower part of the flange is visible. This lower part should lap over the shingle below but not be caulked/sealed.

I have a similar bath fan cap on my roof and it faces North. I can hear it flap a bit in high erratic winds but I've never had any snow or moisture come in. If you are seeing snow packed in the fan housing then it is clear that the flappers aren't blocking the snow. Can you remove the screw holding the mesh and see if the flappers are shutting completely?


----------



## Lazy_Jake

jaros bros. said:


> They don't like to run the vents under the soffits because a lot of the moisture can easily get sucked back into the attic.


Interesting... I have thought about that, but was never really too concerned. I used to instal insulation in 2002 and most if not all vents I worked around went out of the soffit. I guess that the bathroom vents, AKA Fart fans, really didn't dispel a whole lot of water vapor to make it too much of a concern. Where do vents now 'days vent out to, other then the roof top?


----------



## creamaster

Lazy_Jake said:


> Interesting... I have thought about that, but was never really too concerned. I used to instal insulation in 2002 and most if not all vents I worked around went out of the soffit. I guess that the bathroom vents, AKA Fart fans, really didn't dispel a whole lot of water vapor to make it too much of a concern. Where do vents now 'days vent out to, other then the roof top?


 
I saw a Ask This Old House show where they vented the bathroom fan out the sidewall of the house from the attic, the duct run wasn't too far because the wall was right there.


----------



## RedRiver

*Update*

I returned to the roof today. I removed the screens and "flapper" from each of three exhaust fittings on the roof. They seemed to be functioning properly. With the help of my wife, we turned on each fan individually to observe flapper response on the roof. Two of the three appear to be working just fine.

The third one was not functioning.  It appeared that there was no air exiting the roof vent despite an apparently well-functioning fan in the bathroom. There was moisture condensation evident inside this roof vent. By sticking my head up through the attic access, this fan's duct takes a long route to the exhaust vent with several dips and valleys along the way. Could it be that I have a duct filled with enough water to totally obstruct the flow of exhaust?


----------



## creamaster

Try and see if the fan will hold a piece of toilet paper against the grill via suction or if its too high try some smoke and see if the smoke gets sucked through, if both either of these fail then you likely have an air flow restriction. If either pass the test then try to check the duct attatchment at the fan, it may have come off and you might be just venting into the attic.


----------



## oh'mike

Your duct is probably full of water. I've seen that many times with roof vents.

Between moisture condensing in the exposed uninsulated vent tube and the snow blowing in--
Waters going to run down hill--That's why bath vents are often vented through the soffit or wall in cold areas.

Good luck on that---MIKE---


----------



## Hurriken

I wish you guys would have chimed into my thread. Too late now. 
http://www.diychatroom.com/f2/bathroom-fan-not-52880/

Part of the problem is how long you leave the vent on. You most likely keep the vent on long enough to clear the room but you have to give it time to clear the pipe also. If I understand correctly you calculate your CFM and find out how long it takes to exchange the air in the room 8 times and then double that time. I'm a total novice at this but that is what I read.

BTW Mike, I live in Kane County too.


----------



## oh'mike

Well howdy', I like timers on the vent fans. Most people turn the fan off when they leave the room--Best to let it run for a few minutes.

I'm just north of St.Charles,Il.---Mike---


----------



## Hurriken

I'm just off Randall and RT20.

I tried to find a timer to install in my bathroom. the problem is I have two switches and it would take a major modification to do it. It just isn't worth it. Not to mention that those timers are expensive.


----------



## oh'mike

I'm 400 feet east of the Fox river just south of Gilbert rd.

To bad the wiring set would make time install so much work. The switches are PRICY.


----------



## AtlanticWBConst.

Install this type of exaust cover (and install it as it should be: Layered underneath the shingles):

http://www.iaqsource.com/product.php?p=lomanco_evacv&product=171083

This unit us not open to the elements. It has an interior collar, that protrudes up on the inside of the cover. So this keeps water and snow out.


----------



## RedRiver

*Solution Selected - Problem Appears to be Solved!*

Thanks to all for the advice and observations. After considering a number of options, we decided on a contractor's suggestion to reroute the troublesome bathroom vents to soffit exits on the back side of the house. The work was done about four weeks ago. We had a small amount of water dripping just prior to the "fix" and none since. I also replace the conventional manual fan switches with timed switches that permit the fans to remain operational longer without being forgotten "on" for long periods of time. It's hard to determine which of these two variables (1. soffits fan exits, 2. switch timers) made the difference but after some snow, wind, and very cold weather - we have had no further moisture dripping from the fans and the CFM exchange appears to remain as it was under the original installation. Cost: $375. Hopefully, this case is closed.
The original roof vents remain on the roof - blocked. Next spring we will remove the old vents and patch the roof.


----------



## Scuba_Dave

You are not supposed to exhaust the bathroom vents into the soffit area
The moist air will rise up into the vents in the soffit & into the roof decking


----------



## tpolk

I hear thats true dave but I gotta say those look really sharp and I hate making holes in a roof


----------



## jaros bros.

I saw that too Scuba. There's bound to be some moisture sucked back into the soffits that is going to cause mold and mildew. I believe this is against code in quite a few areas now. I think a Panasonic fan with some decent spring loaded roof vents was the solution needed.


----------



## Michael Thomas

I don't know what they are called - I just used to order them through a local sheet-metal shop - but I did manage to find a picture of one: snow and water infiltration resistant roof termination....










- http://www.askthebuilder.com/546_Bathroom_Fan_Ventilation.shtm


----------



## VelvetFoot

Hey, Red, looks good! Proof is in the pudding. I have no problem with mine either. Nothing to get ripped off by sliding snow!


----------



## MJW

May as well just routed them up to the roof vents. Would have saved alot of time and money, but that's what ya get when you get a contractor through a job-lead website I guess. Looks like decent work, but not really correct.


----------



## drtbk4ever

A very sharp looking installation.

Unfortunately, I agree with many others in that in the long run this will create some different issues.

I was watching some home improvement show recently (maybe it was Ask this Old House) where a vent went through the soffit. The moist air was finding it's way back into the attic and there was mold issues on the underside of the roof sheeting.


----------



## Dave The Roofer

*I've always Hated that design - Roof vents*



RedRiver said:


> We live in a three-year-old home in Fargo, ND. We have four bathroom exhaust fans that vent through our roof. Each of them, to some degree, "chatter" and clatter when the wind blows. Even more of a problem is that snow blows in during periods of heavy snow/wind, eventually blocking the duct and/or fan itself. This does not appear to be condensation building up on an inadequately insulated duct. The ducts appear to be properly insulated and installed. When I remove the interior fan cover, one can readily see snow packed in around the fan which ultimately melts and drips down in the bathrooms and damages the ceiling sheetrock. Is my theory of snow infiltration rationale? Does anyone have a recommended solution? Can one purchase some sort of roof vent cover that provides some resistance to opening so it isn't so easily and improperly opened by wind?


I really never liked the roof vent bathroom fan, especially in snow the counrty of Northern States. Keep the roof cleared from snow and ice or vent on the gable ends.


----------



## Gary in WA

“Another common, but unsatisfactory practice, allowing heat to enter the attic, involves installing the bathroom exhaust vent duct into the soffit vents, rather than correctly installing this duct to an outlet vent. Soffit vents are *inlet* vents, not outlet vents! Everything that exits the house at a soffit vent immediately re-enters the house in the attic space, because that is what soffit vents do, they bring in outside air flow. Not only will this add heat, but it will also add humidity and moisture to the attic, defeating the very reason for installing the bathroom fan in the first place. This is a Real Problem! Even a home with functional attic ventilation can now develop molds on the roof sheathing cavities above these unsatisfactory ducts.”--------
http://www.ronhungarter.com/roofing_ventilation.html


Be safe, Gary


----------



## anna design

Lazy_Jake said:


> Interesting... I have thought about that, but was never really too concerned. I used to instal insulation in 2002 and most if not all vents I worked around went out of the soffit. I guess that the bathroom vents, AKA Fart fans, really didn't dispel a whole lot of water vapor to make it too much of a concern. Where do vents now 'days vent out to, other then the roof top?


The quantity of water vapor that is expelled through the bath termination cap in the soffits will evaporate within seconds, not giving the water vapor enough time to recirculate back into the soffit vents. Not to mention, they make special soffit bath termination caps that have a 45 degree bend to them, where it truly redirects the water vapor content away from the home. I would be more concerned about blocked roof cap by snow than a soffit terminated bath vent.


----------



## chandler48

It's a 12 year old thread.


----------

