Is venting fart fans into the attic within code?

[truevalue]

hi:

my specialty is bathroom renovations, and I have delt with all kinds of exhaust fan. and all been vented to the attic, and as builiding inspectors come for inspecting the bathroom they look at the way the fan is vented. all they recommend is that the fan is ducted and if it is ducted to the attic to make sure that the back draft flap is working and the duct hose is as close as possible to the gable vent or any other vent system in the attic to pull the moisture out of the attic.

[hausdok]

Hi,

Here in Washington State, R303.2 is superceded by the Washington State Energy Code. That code specifies that bath ducts and the like must terminate "outside" and in the builder's guide that accompanies that code, Chapter 8, which deals with ventilation, shows various configurations of ventilation systems that are accepted under the code and how they are to be configured. That chapter includes drawings and shows every single duct passing through the attic and then connected to an outlet that discharges outside of the building. You need to find out what they're using there and then obtain a finding from the IRC of what "outside" means in the context of R303.2.

ONE TEAM - ONE FIGHT!!!

Mike

[truevalue]

Isn't it best to observe from the many inspection we do in the area we work at how the majority of exhaust fans are ducted; especialy in new costruction which would pass building code inspection and make a recommendation to clients from there? Since no harm comes from exhaust fans in bathrooms, and it's not a hazard or safety measure, as far as moisture could be trapped in attics from different areas other than exhaust fans, but that wouldn't mean that it's not good venting a system in the attic.

[Chad Fabry]

Mike, I disagree.

I've seen tons of damage in attics resulting from bath fans that are vented to the space.

Mold, delaminated plywood and saturated insulation below condensation points. The fact is, it's prohibited by code and it's a win-win situation when you alert your client to the condition. Common practice is frequently on the wrong side of common sense.

[hausdok]

Originally posted by truevalue

Isn't it best to observe from the many inspection we do in the area we work at how the majority of exhaust fans are ducted; especialy in new costruction which would pass building code inspection and make a recommendation to clients from there?

Well,

When you build something to code you are building it to the absolute lowest possible accepted standard - you're building a Yugo house. If code requires it and a builder isn't doing it, then that builder is constructing a house that is less than the lowest possible accepted standard for quality - in other words, he's building something with below Yugo quality.

Why would you want to follow the examples of those who don't even want to build a home that meets the bare minimum level of adequacy?

I don't know about you, but when I buy a product or hire someone to do a job for me, like build a house, I want that person to show me that he or she is going to be doing more than the bare minimum needed. In other words, I might not be able to afford the Rolls Royce house but I sure as hell don't want the Yugo house; I'm looking for something in-between - something better than the median. I think that's the way that most consumers feel when they have a home built.

When a builder does it less than the Yugo way, we need to call them on it.

ONE TEAM - ONE FIGHT!!!

Mike

[truevalue]

Hi

I can see your point Chad; which makes more sense. In my part it was just a guessing solution to the problem, I guess in another words, if it's done wrong and it works it doesn't make it right.

[SWagar]

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Here is what can happen when the "fart fan" is not directed to the exterior. This growth on the roof sheathing was directly under the exhaust fan duct. You cannot see the duct in the photo but it was below this area by about 12 inches.

[Chad Fabry]

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My favorite example of why venting a bath fan to a soffit is bad.

[toby704]

Can I combine both shower fan and dryer vent to one flex hose?

[hausdok]

No,

Absolutely not. First of all, if you've got a gas dryer you could aspyhyxiate yourself. Second, don't even think about using anything corrugated with a dryer vent - not even the connector from the dryer to the wall. The CPSC did a study of residential fires in the US from 1994 to 1997 and found that more than 17,000 homes burned due to those corrugated vents. You should use only a smooth-walled metal vent, taped at the joints with no screws and clean the thing out every year.

ONE TEAM - ONE FIGHT!!!

Mike

[KGarten]

From the IMC 2003 commentary:

IMC 401.7 "Contaminant Sources" commentary:"As with all exhaust systems addressed in this code, the exhaust must extend to and terminate at he outdoors. The exhaust termination must be approved and comply with sections 401.5 and 401.5.2.

Attics and crawl spaces are not considered to be outdoors and exhaust ducts cannot terminate in these spaces. Exhaust ducts must connect directly to terminals that pass through the building envelope to the outside atmosphere.Pointing, aiming or similarly directing as exhaust pipe as an attic louver, grille, ridge vent, eave vent or soffit vent, for example, in no way ensures that any or all of the exhaust will reach the outdoors. In fact it is possible that the majority, if not all, of the exhaust vapors and gasses will discharge to the attic space rather than the outdoors.

In the case of a duct that turns down to a soffit vent, the exhaust can rise into the attic as opposed to falling through the perforated soffit. The flow of air through any attic ventilation opening is dependent on attic temperature, wind direction, wind speed, and opening configuration and location. In other words, attic air movement is unpredictable and may often be in the opposite direction to that intended. Additionally, grills and louvers offer resistance and interfere with the exhaust flow directed at them. This may cause deflection of exhaust back into the attic. In cold climates, discharge of exhaust air into an attic space can result in moisture condensation on structural and insulation materials."

[Brandon Whitmore]

For you other inspectors in Oregon. Do you call it out when a bathroom exhuast duct is installed up against a roof vent near the ridge?

If the code commentary was included as part of our OR code, I wouldn't be asking this.

I have not been calling this out, as I don't see it cause issues. Jamming an exhaust duct up to an eave vent is another matter.

[Nolan Kienitz]

Routing mechanical exhaust vents to a 'static vent' or 'whirly bird' is at an "exhaust point". OK as far as I read the IRC definition.

Soffit vents at eaves are "air intake" points ... NOT exhaust.

[Jim Katen]

For you other inspectors in Oregon. Do you call it out when a bathroom exhuast duct is installed up against a roof vent near the ridge?

If the code commentary was included as part of our OR code, I wouldn't be asking this.

I have not been calling this out, as I don't see it cause issues. Jamming an exhaust duct up to an eave vent is another matter.

I'm inconsistent. If it's an older house and there's no sign of a problem, I let it pass. If there are signs of moisture problems in the attic, I recommend routing them outdoors with tight vent caps (along with other recommendations.)

- Jim Katen, Oregon

[Jim Katen]

Routing mechanical exhaust vents to a 'static vent' or 'whirly bird' is at an "exhaust point". OK as far as I read the IRC definition.

Soffit vents at eaves are "air intake" points ... NOT exhaust.

I'm becoming increasingly convinced that air doesn't always come in through the soffits and out through the ridge. I know it shows that in the books, but I'm beginning to suspect that some of the air up here has not read the books.

When I started to look for it, I began to find that air very often moved *in* through the upper vents in a roof. The air flows are remarkably chaotic when you start to pay attention to them -- not anything like the neat diagrams in the books. By routing the exhaust ducts entirely to the outdoors, you can take them out of the moisture equation and simplify the troubleshooting process in problem attics.

- Jim Katen, Oregon

[Bain]

Routing mechanical exhaust vents to a 'static vent' or 'whirly bird' is at an "exhaust point". OK as far as I read the IRC definition.

Soffit vents at eaves are "air intake" points ... NOT exhaust.

I'm becoming increasingly convinced that air doesn't always come in through the soffits and out through the ridge. I know it shows that in the books, but I'm beginning to suspect that some of the air up here has not read the books.

When I started to look for it, I began to find that air very often moved *in* through the upper vents in a roof. The air flows are remarkably chaotic when you start to pay attention to them -- not anything like the neat diagrams in the books. By routing the exhaust ducts entirely to the outdoors, you can take them out of the moisture equation and simplify the troubleshooting process in problem attics.

- Jim Katen, Oregon

I've always thought the same thing, but I've seen so many of those diagrams with the little arrows that I always figured there was something going on that I just wasn't getting. Sure, hot air rises. But there's no rule that says the air is required to enter the soffit perforations at a given speed and rate and then be exhausted out of the ridge vent.

And if there's any wind at all, it'll likely enter through the ridge and further complicate matters.

[Jim Katen]

. . . I've always thought the same thing, but I've seen so many of those diagrams with the little arrows that I always figured there was something going on that I just wasn't getting. Sure, hot air rises. But there's no rule that says the air is required to enter the soffit perforations at a given speed and rate and then be exhausted out of the ridge vent.

And if there's any wind at all, it'll likely enter through the ridge and further complicate matters. . .

Indeed. Spend some time hanging out in an attic with a smoke pencil (or it's equivalent) and you'll start to see the arrows pointing in all sorts of different directions. It'll open your mind, man.

- Jim Katen, Oregon

[Brandon Whitmore]

Thanks guys. I seem to be one of the odd men out on another forum I frequent.

Here's what I do-

On newer homes, I write up ducts that are just pushed up against eave vents because I've seen too many issues with this set up. On older homes, it depends on what I see.

At ridge area vents, I don't see problems when the duct is pushed up against these vents, so I don't make an issue of it.

I've got plenty of pictures showing fungal growth at eave bays, but don't see issues at the ridges.

I understand that ridge vents are not always the exhaust vents, but I would argue that they most often are. Otherwise, why do I run into so many problems at eave areas, while not seeing these problems at/ near the ridge?

[kurt]

I agree on the air flow conundrum. Once one understands how and why ventilation requirements were implemented, one understands that no one quite knew what to do, and current venting applications are a shoot from the hip situation to "correct" something folks didn't understand in the first place.

Although, I've never seen a problem with fans discharging directly at a standard roof vent. Seen enough messes with soffit discharge to know it screws things up in cold climates.

[Erby]

Perfect example of fan vented to soffit causing problems:

http://b4uclose.tripod.com/cockamamieph ... -attic?i=3

-

[ericwlewis]

In Indiana, I always write up ANY exhaust duct in ANY age house, that does not have a dedicated roof jack. With several newer homes using attic air to supply combustion air for gas appliances, it just makes good sense. I don't use code as a reference to my recommendations, I use experience and common sense of what's right.

As far as those diagrams with the arrows...... I have found snow and rain water blown IN the ridge and box type vents. Just sayin'.

[fnorman0]

Is what is described as a "fart fan" the exhaust duct from an overhead ventilation fan, or is it the smaller pipe from the back of a Ventextoilet, intended mainly to remove odours not moisture?

[ericwlewis]

Is what is described as a "fart fan" the exhaust duct from an overhead ventilation fan, or is it the smaller pipe from the back of a Ventextoilet, intended mainly to remove odours not moisture?

we were discussing bathroom ventilation fans which are typically mounted to the ceiling and sometimes vented through the roof, sometimes through the soffitt, sometimes into the attic, sometimes near a roof vent and sometimes installed without ductwork! This Ventextoilet you've brought up has a wall mounted vent available so I would recommend treating it the same as a typical vent fan as if it had moisture being exhausted. Why wouldn't there be moisture being drawn out of it?

[dbrickles]

Per the 2009 IRC M1507.2" Exhaust air from bathrooms and toilet rooms shall not discharge into an attic, crawl space or other areas inside the building". 2006 IMC 501.2 " Air shall not be exhausted into an attic or crawl space".