Do I need a bathroom vent?

Question

I recently purchased a duplex with 2 2/1 units.  I'm renovating the unoccupied unit.  The bathroom has a heater and no fan or vent.  I'm planning on replacing the small heater but I'm hoping to avoid running a vent to the outside.  I've seen some of the ventless fans that don't appear to do much.  The place seems to have lasted 46 years without mold/mildew.  Do I absolutely need to put in a fan?  Is there something else I can do?  Thanks

Bob H. · Answer

Regardless of what old codes say, nobody is going to open the window 99% of the year. It's a matter of whether you want to do things right or do things for the lowest possible cost -- but you already knew that.

It's better to put in the fan. If you do, certainly don't make the fan come on every time someone turns on a light to wash hands or brush teeth. That's unnecessarily noisy, wasteful of electricity and annoying. Instead, put in a switch with a timer that has buttons to run the fan for 10, 20 or 30 minutes.

Bryan O. · Answer

@Alex Gordon I want a fan in every bathroom, wired to the light switch. If I held higher end rentals I would consider having one with its own switch. Since you are already in a rehab it is easier to do now and be done with it. Adding it later will be a pain.

Jonathan Jewell · Answer

Check what your local code dictates.  Usually if you have a window that opens within the bathroom a vent isn't required.  However, most of the bathrooms I have seen, the window is usually within the confines of the shower area.  That would be your functioning window, but in real life, most of the time that window usually remains closed.

Here should be your bottom line and what you should be asking yourself:  Will adding this feature make my new tenants happier and possibly stay longer if they are comfortable?  Will this add value (although slight) to my resale down the line?  Both answers would be yes.  If you cheap out now, you will regret it later on down the line.

That's my take on it.

Sam Shueh · Answer

How can there be no mildew in 46 years?  People take shower some longer than others 365 x 46 x persons the amount of vapor moisture where did they go? Big leak, window open in the winter?

Jim Adrian · Answer

@Alex Gordon

Now is the time to add the fan as it will cost you more later.  I would add one now if it was me. The fan can go out the side wall as well which is easier than going thru the roof.  Do not dump the exhaust air into the attic space, major no no.   Code will tell you if you need a fan or the window.

Steve Vaughan · Answer

Without a window, WA definitely requires an exhaust fan.  Every lease has a required Mold & Mildew Addendum. An occasional housing authority inspection will fail, especially if you have remodelled.  At time of sale, the inspection will note this as a repair required anyway.

Is the house made of brick or something?  Install a fan.

Michael Noto · Answer

@Alex Gordon From seeing apartments in about every condition you can imagine in the last decade I would highly recommend putting a light/bathroom fan combo in so the tenants do not have to even think to put the fan on.  If you don't, even with a window in the bathroom I can guarantee you will have mold on the ceiling when they move out.

Rob Myers · Answer

Where I am located, code dictates a fan/vent or an operable window in a bathroom.  At this point, it's your preference since it doesn't sound like you are in the middle of any major rehab that would necessitate an inspection.  If you do elect to install an exhaust fan, make sure to wire it on the same switch as the light in the bathroom - basically always on.  If you leave it switched separately, it may not get used as intended and you will end up having issues with the motor failing prematurely.

Tanya F. · Answer

Even with a window in the bathroom, our city code requires a fan for new construction.

There are really quiet fans out there now. There are automatic timers/controllers that have the fan run every 15 minutes. We got a quiet fan with such a timer/controller at the recommendation of our energy auditor.

It doesn't cost that much and is good for the health of your house.

Do I need a bathroom vent?

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