Soffit venting for bath fan OK?

We are converting a bedroom into a master bath. 60’s ranch, brick exterior, hip roof, full basement. The room in question is in the North corner of the house on the top level. We live in NW Arkansas … 6A.

We are using a quiet, 150 CFM Broan exhaust fan. I want to vent it into the soffit, which is about 18" wide and about 6’ away from the fan. We will be using insulated 6" flexible duct. We have soffit vents and a ridge cap vent to vent the attic space.

Does all of this sound OK? If so, do you have any recommendations for a termination hood for the soffit? If some of our strategy is bad, please advise as to how we can better exhaust the bath. Lastly, do we need a backdraft damper, and if so, exactly how should that be installed?

On a different note, how would you recommend we insulate the two exterior walls? 2x4 with brick veneer. Paper-sided pink and no vapor barrier? Plastic wrapped fiberglass by Johns-Manville? Some other way?

Thanks for your help in advance.


Soffit vents are air intakes and will suck that moisture laden air your trying to exhaust from your shower right onto your attic sheathing - bad idea.

Thanks for your help, Joshua.

My intent was to have a separate soffit vent to exhaust the bath and to not use one of the existing soffit vents that is used for intake to vent the attic. Also, to place it away from an attic soffit vent so the moisture is not just sucked back into the attic. That OK?

Any thoughts on my insulation?

At least you’re thinking…

And, this may be helpful:–White_p_27.html

My intent is to exhaust the bath fan into its on soffit vent that is not close to one of the soffit vents that is part of the attic ventilation.

If I use insulated rigid pipe to the eave (sloped towards the eave) and a little insulated flex pipe to connect to the dedicated soffit vent, would that not be OK? The fan has a backdraft damper.

I was assuming you were going to use a “dedicated” exhaust. Still not a good idea. That moisture tends to “hang around” the soffits and eventually get sucked in at the nearest vent. You mentioned that its a hip roof, that’d more than likely be a pain getting it out there anyway, no? Is there a reason you can’t go out the roof? Anyway, here’s a link that may help too. Good luck.

This type of soffit / eave vent is commonly used for bathroom vent fans.

NO! Do not vent it into the soffit space. If you want to vent though the soffit, use one of the fittings like those posted earlier, but do NOT vent into the soffit. You need to vent the moisture laden air completely outside of the structure.

The answers to your insulation questions are entirely dependent on where you are located. The correct answer for one of my clients in subtropical Houston would not be the right answer for someone in Chicago.

BTW: Real Honest men use real names.

I agree with you Charley how ever code guys allow it here , do not ask me why but they do

You talking to me or that short Okie guy?

The OP was asking was it OK. It’s not, regardless of whether the AHJs allow it or not. They allow it here too, but it’s still improper and can be very detrimental to the structure, especially in northern climates.

Contractors may take such shortcuts, but the homeowner who comes here asking if it’s OK, probably doesn’t intend to take such a shortcut if it can harm his home. Especially when the proper method is not much more difficult or expensive.

So, do you report that in RED or BLUE ink??? :roll::roll::roll:

What are you smoking, I am not in this dance

Now I got a stalker / twit

Try to stay on topic

[quote=“cevans, post:10, topic:72582”]

You talking to me or that short Okie guy?QUOTE]

We may be short but thoseTexans got ran over by a short train yesterday what happened, they forget to get off the bus:twisted:

Most reasonable people agree that moist air should discharge to the exterior of the home without question. There are some AHJ including mine that allow kitchen and bathroom exhaust to be discharged into the attic because the attic is considered a vented area with the proper amount of air changes for its size

Lord someone got up the wrong side of the bed.
I meant Chuck , sorry about that , i do not smoke any thing that is not legal .Have you be hanging out with Larson? lol;-)