Bathroom fan venting

yes it’s “legal” (not much is “illegal” in this basackwards state) but I still don’t like this as general practices go. To great a probability of adding moisture/elevated humidity levels to the attic space. (imho) Never mind the fact that getting a builder to install gutters is like pulling teeth.

What say you?

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You guys are on a run today! What is with all this “code” and “legal” stuff?

At least they vented it to the outside!
If I got $1 for every un-vented vent I come across…

I agree with David. It would have been nice if they had skipped the vented piece of soffit in the immediate area to reduce the risk of running the vented air right back up into the attic----but at least it isn’t venting to the back side of the soffit like the two I had yesterday:D </IMG>

Attached is what I find aboout 33% of the time. Exhaust in the attic under the insulation.

The other is where the exhaust blows on the sheathing.

Would take an additional 15 minutes and $10.00 to do it right when being built.




I see these on an everyday basis and have never run into moisture issues in the attic at that location. They are absolutely fine. I just make sure they are connected.

I always enjoy the “duck tape to the nail” installation method.

Was the second photo taken in a townhome?

I’m kind of curious to see where this thread goes, I’ve been asked to vent 2 bathrooms in a reno and the only place available is either through the roof or through the soffit. I’m looking at both the pro’s and con’s.

There’s nothing wrong with venting your bathroom fans into the soffit area.

A roof penetration would be susceptible to leaks.

Thanks David. Those were my thoughts as well. I just put a new roof on this one last year and I just dont like going through a roof for venting a fan.
I inspected a house 2 years ago that had all 3 bath fan vents connected to the main stink-pipe. Had another where 2 were ducted to the roof vents.

Use the soffit with pre-made louvered covers. They’re fine.

Thanks David. That’s what the owner bought.

Ditto that…

ditto the Thank-you;-)

I’m not afraid to vent through the roof. Just know how to seal it well. I installed a great roof vent manufacturered by Broan last fall…a bit expensive but if you want quality, be prepared to pay for it. I tell clients now that if they want a decent bath fan system,(powerful, quiet, controlled by a timer on a circuit different from the bath lights,and vented to the outside) be prepared to pay at least $325-$350 upwards +taxes.

That may work in warm Atlanta but in cold areas, this is a recipe for part of the condensation that may be found in an attic and can lead to mould growth/sheathing rot.

I’ve seen hundreds of these bathroom soffit vents and never once found condensation issues on the sheathing above relating to the bathroom vent below.

They are fine.

Went back to the beginning of the thread and saw that I was talking about a different situation. When your post said “into”, I assumed it was not vented down through the soffit material to the outdoors but up above the soffit into the triangular cavity formed by the eave extension. I have seen problems with this, even with venting soffit materials

I have only seen minor condensation problems or mould twice with the air vented down through the soffit to outdoors.

No, I did not intend make it sound like it is OK for an installation in the soffit interior. I should have stated “into and out of”. That just doesn’t make sense. An interior type of vent installation is definitely conducive to MOLD build-up.

All vents must extend to the exterior, no matter where it is.

I disagree with the venting of the moist humid air to the soffits, which have fresh air intake vents installed in them. It would depend on how close the next intake vent inlet were to be placed, but all in all, I think it is bad practice and asking for trouble.

I copy/pasted a recent response I made in the JLC Forums regarding the same topic.

Please check out the link for “Scary Stories From The Attic, Part 1”.


The Soffit Intake Vents, by their very design and nature is intended to promote the flowage of exterior air back into the attic cavity.

By expelling the moist humid air content from the bathroom exhaust directly to where the adjoining intake opening are located suggests that moisure and mold problems will occur.

I will find a link to and article by Ron Hungartner, and he completely captures this scenarion in several well written articles with illustrative photos included.

Read the article, “Scary Stories” and “Attic Heat” first, if I recollect correctly.