Bathroom fan venting question

[oldsparky52]

I have never gotten around to replacing the non vented bathroom fans that were originally installed in my home. I was talking to a friend of mine discussing how I would do it (after I lost some weight) and how much I hated the idea and process of doing it.

Anyway, the discussion of venting came up and he was of the opinion that pointing the vent duct to the ridge vent would be fine. I know that's what a lot of people did in the early 70's, but ... IDK. My buddy (who is pretty sharp) said there would not be enough moisture to be a problem. I'm a little dubious about this since this practice was banned (where I worked) in the mid 70's.

I am soliciting comments/opinions on whether it is okay to just run the vent duct to the ridge vent of the roof, or am I asking for trouble if I do this?

 

[James L]

I have never gotten around to replacing the non vented bathroom fans that were originally installed in my home. I was talking to a friend of mine discussing how I would do it (after I lost some weight) and how much I hated the idea and process of doing it.

Anyway, the discussion of venting came up and he was of the opinion that pointing the vent duct to the ridge vent would be fine. I know that's what a lot of people did in the early 70's, but ... IDK. My buddy (who is pretty sharp) said there would not be enough moisture to be a problem. I'm a little dubious about this since this practice was banned (where I worked) in the mid 70's.

I am soliciting comments/opinions on whether it is okay to just run the vent duct to the ridge vent of the roof, or am I asking for trouble if I do this?

Exhaust is supposed to leave the house. Through the roof, a wall, a soffit, etc.

 

[infinity]

Through the roof venting is the preferred method. I would guess that ridge vent venting is better than just dumping the exhaust into the attic. There is some debate about soffit vents being a poor choice because the exhaust air ends up getting sucked back into the attic. Three of the bathroom fans in my home are vented into the attic. I've already replaced one of them and added a vent cap through the roof.

 

[James L]

CHAPTER 15 EXHAUST SYSTEMS - 2018 INTERNATIONAL RESIDENTIAL CODE (IRC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

 

[oldsparky52]

Through the roof venting is the preferred method. I would guess that ridge vent venting is better than just dumping the exhaust into the attic. There is some debate about soffit vents being a poor choice because the exhaust air ends up getting sucked back into the attic. Three of the bathroom fans in my home are vented into the attic. I've already replaced one of them and added a vent cap through the roof.

I was going to vent through the soffit so I appreciate your comment on that. I guess if I spent the money to go through the roof, I would need a separate vent for each fan or could I tie both fans into one vent (through the roof)?

 

[Fred B]

I was going to vent through the soffit so I appreciate your comment on that. I guess if I spent the money to go through the roof, I would need a separate vent for each fan or could I tie both fans into one vent (through the roof)?

Another option if its available is a gable end vent, I usually don't like through the roof, it gives one more point of water penetration. And depending on the roofing material and age it can be even more difficult to get a good seal.

 

[retirede]

My house vents into the attic as does every new home being built in this area.

I’ve never heard of any problems with them being done that way. A well-vented attic is probably why.

My attic has a small storage area and I get up there regularly. I’ve never seen any sign of moisture, mold or anything that would indicate a problem. And I used to look for it when we first moved in, not so much any more.

My range hood is ducted through the roof. I wouldn’t want everything up there to smell like grease, curry, fried fish, or whatever else I’m cooking!

 

[infinity]

As James posted in post #4 many types of common venting are prohibited by mechanical codes or building codes. If the house has a ridge vent or a roof ventilation fan using a soffit vent will just allow the moist exhaust to be pulled back into the attic through the soffit. A roof or gable vent is the way to go. I've cut in many roof caps and never had a leak. They're not very difficult to install properly but I can see why someone would be reluctant to do so.

 

[romex jockey]

ice damns are what happens on my turf ~RJ~

 

[James L]

A roof or gable vent is the way to go. I've cut in many roof caps and never had a leak. They're not very difficult to install properly but I can see why someone would be reluctant to do so.

For sure, it's not near as difficult as most people think

 

[ptonsparky]

I have one roof vent, two eave, and one thru the wall. My kitchen range hood used to vent thu the roof. It was a cold spot and nothing appeared to vent while in operation so it was plugged."

The master bath roof vent works well other than the roof damper slaps and bangs in the wind. Not as bad as it used to be, but that could be because, neither is my hearing.

 

[Hv&Lv]

My house vents into the attic as does every new home being built in this area.

I’ve never heard of any problems with them being done that way. A well-vented attic is probably why.

My attic has a small storage area and I get up there regularly. I’ve never seen any sign of moisture, mold or anything that would indicate a problem. And I used to look for it when we first moved in, not so much any more.

My range hood is ducted through the roof. I wouldn’t want everything up there to smell like grease, curry, fried fish, or whatever else I’m cooking!

This is from dupage county:

501.3 Exhaust Discharge

The air removed by every mechanical exhaust system shall be discharged outdoors at a point where it will not cause a public nuisance and not less than the distances specified in Section 501.3.1. The air shall be discharged to a location from which it cannot again be readily drawn in by a ventilating system. Air shall not be exhausted into an attic, crawl space, or be directed onto walkways.

Exceptions:

1. Whole-house ventilation-type attic fans shall be permitted to discharge into the attic space of dwelling units having private attics.
2. Commercial cooking recirculating systems.
3. Where installed in accordance with the manufacturer's instructions and where mechanical or natural ventilation is otherwise provided in accordance with Chapter 4, listed and labeled domestic ductless range hoods shall not be required to discharge to the outdoors.

Apparently inspectors aren’t looking for it, or don’t care.

To me, it’s like splicing wire in the attic without a box.

 

[Hv&Lv]

I have never gotten around to replacing the non vented bathroom fans that were originally installed in my home. I was talking to a friend of mine discussing how I would do it (after I lost some weight) and how much I hated the idea and process of doing it.

Anyway, the discussion of venting came up and he was of the opinion that pointing the vent duct to the ridge vent would be fine. I know that's what a lot of people did in the early 70's, but ... IDK. My buddy (who is pretty sharp) said there would not be enough moisture to be a problem. I'm a little dubious about this since this practice was banned (where I worked) in the mid 70's.

I am soliciting comments/opinions on whether it is okay to just run the vent duct to the ridge vent of the roof, or am I asking for trouble if I do this?

you ever noticed your mirrors fogging up after a shower? Or stepped out and can’t see because of the steam?
All that exhausted in the attic feeds molds that can’t be seen, and adds moisture to the underside of the sheathing.
its really not cold enough in NC to have icicles hanging from attic vented fans, but it does happen farther north.
Wilmington gets humid enough, why add more?

 

[kwired]

I built my home in 2005. I thought I was doing right thing by venting them through the roof, and did same many other places I did installs around then.

Since then I have been called back to some of them as well as made changes to my own for problems those of you down south probably never have.

Cold windy winter days and cold bathrooms because the wind is able to open the damper on the roof cap are not what makes a client happy. Too strong of a spring for the damper and it won't open under normal conditions and is worthless anyway.

On top of that moisture condenses in the duct and when cold enough freezes in there, and continues to build up for how ever long the cold event lasts. When it finally warms up it runs back to the bathroom and drips out from the exhaust fan location. If you happen to use flex duct and have a natural "P trap" in it, by way it is routed or even settles down, it fills up and you get no air flow when the fan is in use.

A basement bath or any other non upper level bath usually has little choice but out the wall, those don't seem to have as much trouble on those windy days as roof cap vents do though. I now typically run them to the eave if possible and try to make sure the duct slopes away from the fan, tape seams in rigid duct so condensation won't drip out the seam and get the drywall wet. Hardly ever see anything but vented aluminum soffit panels around here so it can drip onto that and drain outside if necessary. If their attic is ventilated properly it won't sustain that much damage. Winter months are probably the worst situation, summer months that moisture gets heated enough it isn't heavy water vapor it gets well absorbed by the air, and the extra heat in the summer creates even more draft in natural convection ventilation systems. Attics with low pitch roofs maybe are the ones with more troubles if you don't get it vented completely outside as they are more difficult to get sufficient ventilation through them.

 

[Mystic Pools]

Mine runs up into the attic, which has quite a bit of room. Nearly 9' of height at the peak.
It exhausts through the side of the house, which faces mostly west. Typical dryer vent assembly with a flex hose. No issues with any wind messing the flapper and allowing cold air in.

I have plans to reno the bathroom, vault the ceiling and add a vented skylight. I still intend to have a fan. I"ll use rigid pipe instead of the flex.

I changed the dryer to rigid as the flex captures the lint and impedes air flow. It makes the dryer work harder if it's clogged up.
You can't really can't clean out flex anyway. I'll periodically run the long bristle brush through the dryer vent to keep it clean.

 

[kwired]

Mine runs up into the attic, which has quite a bit of room. Nearly 9' of height at the peak.
It exhausts through the side of the house, which faces mostly west. Typical dryer vent assembly with a flex hose. No issues with any wind messing the flapper and allowing cold air in.

I have plans to reno the bathroom, vault the ceiling and add a vented skylight. I still intend to have a fan. I"ll use rigid pipe instead of the flex.

I changed the dryer to rigid as the flex captures the lint and impedes air flow. It makes the dryer work harder if it's clogged up.
You can't really can't clean out flex anyway. I'll periodically run the long bristle brush through the dryer vent to keep it clean.

Are you out in middle of nowhere with 40+ MPH winds at times? I could get away with more on many houses in town as there is more "wind breaks" in town than out in the country. There is a reason there are wind farms being built around here. Only time we want wind seems to be in middle of July/August when it is hot, humid and there isn't even a slight breeze at ground level.

 

[ptonsparky]

Don't use hard plastic pipe on the dryer. Lint sticks to the side walls.

 

[Hv&Lv]

Don't use hard plastic pipe on the dryer. Lint sticks to the side walls.

Is there anything lint doesn’t stick to?

 

[kwired]

Don't use hard plastic pipe on the dryer. Lint sticks to the side walls.

Is there anything lint doesn’t stick to?

I could see build up because of static electricity being worse with PVC pipe.

 

[drcampbell]

Pointing the duct at the ridge vent will probably work in winter, when you're dumping warm, buoyant air into cold.
Not so in the summer when you're dumping cool air into warm.

Ice dams have nothing to do with exhaust fans; they're the result of inadequate attic ventilation and/or insulation that enables a warm roof to melt snow upward from the bottom.