None of the exhaust fans in my house are vented outside, all vent into the attic. I am going to add roof vents, but want to be sure I think of everything and know almost everything before hand.

-Can I use a vent cap or do I need a vent pole?
-Can multiple fans exhaust to the same vent?

Is it as easy as purchasing this kit and getting to work?

http://www.homedepot.com/p/Broan-Roof-Vent-Kit-RVK1A/100344509#.UgpQtpKG3As

If you have soffit vents just route the duct to the nearest soffit vent. You do not have to install termination, just let the duct sit near the soffit vent inside the eave.

Routing to soffit vents is against building code. You generally want the exhaust to run as near vertical as possible. Now, if you are on an exterior wall within a few feet of a soffit vent, I would probably run that route due to ease.

For exhaust fans, you'll want to use a cap. The poles are for plumbing vents. I used a similar vent and insulated duct earlier this year to exhaust one more of my bath fans (one left to go) and the installation is kind of a PITA. The biggest problem I had was trying to fit the vent into place under the top row of shingles with the insulated duct already secured to the back of the vent. I ended up installing the hood first, then secured the metal adapter and duct from inside the attic. Everything still looks fine and I pookied the sh*t out of the roof opening.

Gable venting is the easiest to weatherproof.

Venting through a soffit is better than a roof penetration, but, on the windward side of the house is likely to just wind up back in a vented attic.

Venting just "to" a soffit vent is a great way to ruin the soffit and the vent--you are dumping damp air, damp conditioned air on the back of plywood and a thin metal vent. It's also a code violation most places, too.

You can combine vents. The queitest venting solutions of all, have the fan at (or near) the exhaust end, and duct back to the bathroom intake grille. Only hassle there is in wiring all the switches to the fan unit.

Through the roof, you want a "mushroom" vent of enough CFM capacity to accommodate the air flow. if you have combined two fans, you need to handle that combined load.

Can you show me what section of the most current irc makes terminating to soffit vents against code ?


Have they changed the exception that used to allow this ?

Can you show me what section of the most current irc makes terminating to soffit vents against code ?


Have they changed the exception that used to allow this ?

I'll have to see if I've got a copy of the code at the office. When I was researching this before my first vent revision, it read something along the lines of "no exhaust shall vent to attic or crawl space nor soffit or ridge vents."

It used to be permissible to simply route ducting to the soffit, but now requires direct venting to the outside. You can route it through the soffit, but the ducting must actually vent through a dedicated soffit vent (example http://www.lowes.com/pd_317949-85334-VTL0021_0__?productId=3126431&Ntt=soffit+vent&pl=1¤tURL=%3FNtt%3Dsoffit%2Bvent&facetInfo=.

Couldn't find the code JP, maybe someone more in tune with residential construction will have it.

Even a true soffit vent for the exhaust sounds like a bad idea to me and I'll continue to take chances by cutting holes in roofs to install roof vents for my bathroom ventilation.

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Even a true soffit vent for the exhaust sounds like a bad idea to me and I'll continue to take chances by cutting holes in roofs to install roof vents for my bathroom ventilation.

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Everything I can find shows about equal risks with both.

The idea of humid air reentering the soffit is not that big a deal b/c it is exhausted out with a decent velocity allowing good mixture before any chance of being sucked back into the soffit vent.

The roof vent adds another roof penetration which introduces another potential leak point, but that is handled by making sure that you do good work.

Seems like the pertinent code:

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M1507.2 Recirculation of air.
Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms and toilet rooms shall not discharge into an attic, crawl space or other areas inside the building.

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Along with

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R303.3 Bathrooms.
Bathrooms, water closet compartments and other similar rooms shall be provided with aggregate glazing area in windows of not less than 3 square feet (0.3 m2), one-half of which must be openable.

Exception: The glazed areas shall not be required where artificial light and a local exhaust system are provided. The minimum local exhaust rates shall be determined in accordance with Section M1507. Exhaust air from the space shall be exhausted directly to the outdoors.

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doesn't show exceptions for dumping into a soffit.

If the duct is ran directly to an existing soffit vent how is it not venting outdoors?


I know in the bcs area you can still terminate on top of a soffit vent and pass inspection.



As far as humidity issue, I think location would determine proper exit. If you are in Houston And outside humidity is 95% then it does not really matter how it is vented.

Thanks.

So the conclusion is I can vent to the soffit, but should use a vent as previously linked?

I'm in Katy, so don't know if there are codes.

Anything I do is better then not being vented which is how it is now, and how it has been for the last 30 years.

I used the kit in the first post to vent my bathroom fans. It was pretty easy to use. I just got some roofing caulk to seal the shingles around the vent cap. From what I read, it is better to use rigid pipe, but I went ahead and used the flexible duct.