My neighbor installed a bathroom exhaust that ventilates into my bedroom window

[Alice T]

Hi. I would like some advice on what to do. I live in San Francisco, CA. My neighbor recently installed an exhaust fan from their bathroom that exhausts out into a shared lightwell space. The houses are pretty much side by side and this lightwell space is all the light and air i have in my bedroom. It is the only window. The exhaust was installed just recently. Now whenever my neighbor showers and does their number 2 business, I get all the aroma streaming into my room.

Can they legally do this? It is very unpleasant. The smell is the worse. Also sucks now that I have to hear the exhaust fan turn on every so often in the middle of the night. Attached is a rough illustration of my situation.

[Jerry Peck]

Base on your drawing, it is quite likely that your neighbor violated several sections of the building codes.

Take your drawing down to the building department and go over it with them.

They can do something about it, which is not to say that they will do something about it.

[JC Warner]

I feel your pain, Alice! I lived in an apartment in the Marina for a few months, shared a lightwell with 7 other bathrooms. Beside the echoing noises, the smell was quite robust at times.
Wishing you much success in rectifying this matter. :D

[JeffGHooper]

Listen to Jerry. An exhaust fan may not terminate where it can be readily drawn into a building or structure. There re minimum clearances to building openings.

[Billy Stephens]

Hi. I would like some advice on what to do. I live in San Francisco, CA. My neighbor recently installed an exhaust fan from their bathroom that exhausts out into a shared lightwell space. The houses are pretty much side by side and this lightwell space is all the light and air i have in my bedroom. It is the only window. The exhaust was installed just recently. Now whenever my neighbor showers and does their number 2 business, I get all the aroma streaming into my room.

Can they legally do this? It is very unpleasant. The smell is the worse. Also sucks now that I have to hear the exhaust fan turn on every so often in the middle of the night. Attached is a rough illustration of my situation.

Hi Alice,

Does your bathroom have an Exhaust Fan and if so where does it exhaust to?

[Jerry Peck]

Hi Alice,

Does your bathroom have an Exhaust Fan and if so where does it exhaust to?

I'm going to guess it is the same as the neighbor's was - a window (no exhaust fan required).

Or, if the building is from back in the 1960's-80's, may places allowed recirculating fans with charcoal filters - which was not really permitted by the codes, but that was back when bath fans were called "fart fans" and the charcoal filter was to take out the odors ... while the code requirement was not for "fart fans", the code requirement was for "exhaust fans" (because of the moisture generated in bathrooms).

AHJ sometimes have their own quirky way of rationalizing things ... until it back fires on them.

[Alice T]

Base on your drawing, it is quite likely that your neighbor violated several sections of the building codes.
Take your drawing down to the building department and go over it with them.
They can do something about it, which is not to say that they will do something about it.

Thanks Jerry. I will look towards doing that if my neighbor won't mutually try to fix it in a considerate manner. I am hoping someone knew the precise laws.


I feel your pain, Alice! I lived in an apartment in the Marina for a few months, shared a lightwell with 7 other bathrooms. Beside the echoing noises, the smell was quite robust at times.
Wishing you much success in rectifying this matter. :D

Did you ever find a solution to your problem?


Hi Alice,

Does your bathroom have an Exhaust Fan and if so where does it exhaust to?

The exhaust fans in our apartment actually routes to the roof over neighboring buildings. I'm guessing my neighbor should do the same at the very least.

[Jerry Peck]

I am hoping someone knew the precise laws.

That depends on when the building was constructed (the code in effect at that time) and (for new work) the code in effect at the time the new work was done.

The 2013 San Francisco and California codes:
- Codes | Department of Building Inspection (http://sfdbi.org/codes)

In a brief review of the San Francisco Mechanical Code shown as currently being in effect ( http://www.iapmo.org/2013%20California%20Mechanical%20Code/Chapter%2004.pdf ), and its unusual layout for exhaust and ventilation requirements, I was able to find a section for exhaust outlets, albeit not where I thought I would find it.

From the 2013 California Mechanical Code:
- 407.0 Ventilation System Details.
- - 407.2 Outdoor Air Intakes and Exhaust Outlets.
- - - 407.2.2 Exhaust Outlets. Exhaust outlets shall be located a minimum of 10 feet (3048 mm) from doors, occupied areas, and operable windows.
- - - Exception: Airborne infection isolation rooms shall comply with Section 414.1.

As I suspected (based on what I could find in that non-user friendly access to the 2013 California Building Code), that exhaust discharge opening is to be a minimum of 10 feet from an operable window.

Now, if that window can be considered as an 'air intake' (sometimes a stretch and sometimes not, all depends on the wording in the code, and that code is not user friendly to look for it), 407.2 Outdoor Air Intakes may be able to be applied (not that it is necessary as your drawing and post indicates there is less than 10 feet between the exhaust and the window) - "407.2.1 Outdoor Air Intakes. Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems ... (blah-blah-blah)".

The reason it may be able to be applied is that the bedroom is required to have natural ventilation, thus the window - that makes the window an "intake opening". The reason it may not be able to be applied is that some codes apply the term "intake opening" with a qualifier, i.e., "mechanical air intake opening" or wording to that effect.

Thus we need to go to the definitions:
( http://www.iapmo.org/2013%20California%20Mechanical%20Code/Chapter%2002.pdf )
- Air Intakes. An opening in a building's envelope whose purpose is to allow outside air to be drawn into the structure to replace inside air that is removed by an exhaust system or to improve the quality of the inside air by providing a source of air having a lower concentration of odors, suspended particles, or heating content.

Seems like that definition could be applied to a window ... :biggrin:

Of course, though, if the exhaust opening is not at least 10 feet away from the operable window ... going to 25 feet does not matter anyway, it is just ... :deadhorse:

[JeffGHooper]

That depends on when the building was constructed (the code in effect at that time) and (for new work) the code in effect at the time the new work was done.

The 2013 San Francisco and California codes:
- Codes | Department of Building Inspection (http://sfdbi.org/codes)

In a brief review of the San Francisco Mechanical Code shown as currently being in effect ( http://www.iapmo.org/2013%20California%20Mechanical%20Code/Chapter%2004.pdf ), and its unusual layout for exhaust and ventilation requirements, I was able to find a section for exhaust outlets, albeit not where I thought I would find it.

From the 2013 California Mechanical Code:
- 407.0 Ventilation System Details.
- - 407.2 Outdoor Air Intakes and Exhaust Outlets.
- - - 407.2.2 Exhaust Outlets. Exhaust outlets shall be located a minimum of 10 feet (3048 mm) from doors, occupied areas, and operable windows.
- - - Exception: Airborne infection isolation rooms shall comply with Section 414.1.

As I suspected (based on what I could find in that non-user friendly access to the 2013 California Building Code), that exhaust discharge opening is to be a minimum of 10 feet from an operable window.

Now, if that window can be considered as an 'air intake' (sometimes a stretch and sometimes not, all depends on the wording in the code, and that code is not user friendly to look for it), 407.2 Outdoor Air Intakes may be able to be applied (not that it is necessary as your drawing and post indicates there is less than 10 feet between the exhaust and the window) - "407.2.1 Outdoor Air Intakes. Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems ... (blah-blah-blah)".

The reason it may be able to be applied is that the bedroom is required to have natural ventilation, thus the window - that makes the window an "intake opening". The reason it may not be able to be applied is that some codes apply the term "intake opening" with a qualifier, i.e., "mechanical air intake opening" or wording to that effect.

Thus we need to go to the definitions:
( http://www.iapmo.org/2013%20California%20Mechanical%20Code/Chapter%2002.pdf )
- Air Intakes. An opening in a building's envelope whose purpose is to allow outside air to be drawn into the structure to replace inside air that is removed by an exhaust system or to improve the quality of the inside air by providing a source of air having a lower concentration of odors, suspended particles, or heating content.

Seems like that definition could be applied to a window ... :biggrin:

Of course, though, if the exhaust opening is not at least 10 feet away from the operable window ... going to 25 feet does not matter anyway, it is just ... :deadhorse:

Says it all. 407.2.2 Exhaust Outlets. Exhaust outlets shall be located a minimum of 10 feet (3048 mm) from doors, occupied areas, and operable windows.

Not allowed as drawn.

[Chris Weekly]

I agree with the 10' rule. It may be possible for that owner to have a sheet metal duct extended upward to the roof, from the existing termination (which happens to point at your bedroom window).
I know the light wells in SF can be a bit troublesome or challenging for various privacy reasons. I hadn't thought about the smell factor until now....Thank you for bringing that up.

BTW - that is a very cool drawing you did. What program is that...and can a computer klutz use it easily?

[Jerry Peck]

I thought I would introduce another aspect into the picture to be considered: fire-separation between buildings.

How far apart are the buildings?

Are the exterior walls fire-rated to what rating?

And there are operable windows in those walls, making for some interesting calculations for openings allowed in a rated wall ...

Just pondering some additional ponderables.

I thought the drawings were neat too.

[Chris Weekly]

Jerry these are typically 60 to 80 year old buildings (2, sometimes 3 stories) with inches separating them, but with a light well for consideration of light, ventilation and egress. The light well may be 5' building to building. The ground floor or bottom of the light well leads to covered walks, or garages that will lead to a public walkway.
Fire separation? This is San Francisco.

[Jerry Peck]

Jerry these are typically 60 to 80 year old buildings (2, sometimes 3 stories) with inches separating them, but with a light well for consideration of light, ventilation and egress. The light well may be 5' building to building. The ground floor or bottom of the light well leads to covered walks, or garages that will lead to a public walkway.
Fire separation? This is San Francisco.

Kind of how I visualized the buildings - my wife and I were in San Francisco for about a week total about 5-1/2 years ago (went to visit friends in Northern California up near Oregon, flew into and out of San Francisco, spending some time there) ... that was my memory of most of what I saw.

Even back then, and especially back then, I would have thought that they would have had fire separation codes (the 1906 San Francisco conflagration would still have been "a recent memory" during that time).

The neighbor across the alleyway may not have had a bathroom exhaust fan, just the window to be opened, and being as almost no one opens the window for venting out the moisture, they may have installed a bathroom exhaust fan - which could easily mean:
- no electrical permit (possible fire hazard and electrical shock hazard)
- no mechanical permit (light and ventilation hazard - ventilation affecting the building across the alley, which lead to the original post)
- potentially unsafe work for both of the above (especially based on the outcome as has been reported to us)
- and who knows what else that "handy tenant" (not even an owner) may have done inside their apartment

[Alice T]

Thanks Jerry and Chris for all the information. The metal duct extension seems like a viable option that I hope my neighbor would agree to, else I'll bring the issue to dept of building inspections.

And yeah, there isn't really fire separation in most parts of San Francisco. Any separation will probably lead to a posting on Craigslist for a "Cozy 1br studio with open floor plan at 3000/mo" (A SF local joke for the exuberant, skyrocketing housing market)

@Chris I made the quick sketch (with my finger) on my iPad on the train to work. It's a free app called Autodesk Sketchbook. The tools seem rather intuitive if you want to do simple napkin drawings and flexible enough to create more time consuming masterpieces utilizing a stylus. I think if you can handle MS Paint, you will be at home with it. I believe Android has it, as well as PC and OSX.

[Chris Weekly]

Thank you Alice. I like intuitive.
I'll look into that and see if I can utilize that in my inspections. I have a tablet that tags along with me. I find myself often trying to draw on paper with pen or pencil something for a client like a foundation element or a truss, etc and would like instead to do what you have done. Your drawing was a nice example.
Oh, and yes, I hope you are able to reason with the neighbor...or, rather your neighbor is a reasonable person - and sees the problem (from your point of view) that he has caused. And certainly, as Jerry has stated - that work typically requires permit approval, and to conform to building standards.

[Chris Weekly]

Jerry I remember you or Gunnar posting once about your lunch together with west coast Jerry when you came out. WC Jerry was a wealth of knowledge and an all around good guy - did you get to see SF with him or take a small tour? Just to see some of the interesting building practices...like some of the Victorian ladies with their coal burning fireplaces, or the more modern unvented gas heaters. Must have been a blast.

[Jerry Peck]

Jerry I remember you or Gunnar posting once about your lunch together with west coast Jerry when you came out. WC Jerry was a wealth of knowledge and an all around good guy - did you get to see SF with him or take a small tour? Just to see some of the interesting building practices...like some of the Victorian ladies with their coal burning fireplaces, or the more modern unvented gas heaters. Must have been a blast.

My wife and I had lunch with West Coast Jerry and Gunnar the day after we arrived (as I recall), then dinner with Gunnar on our way back down from Northern California.

It was really great meeting WC Jerry and Gunnar.

We didn't get a tour of San Francisco, but we spend 2-4 days there when we arrived and had a chance to wander around on our own (what I recall the most was the cost of parking $50 a night at the hotel and $25 a day at each lot we parked at, so we tried to park in as few places as possible and walked the surrounding area).

Got to drive up the hill, over the top, then down that winding street (like all tourists did) - Lombard Street ( https://blog.parkme.com/2013/04/02/lombard-street-parking/ ).

[Mark Hagenlock]

Alice,
This is not meant to be a rude question but, what is it worth to you, to have this problem go away? I suggest you have a contractor come over and figure out a solution (and $ estimate) which theoretically leaves both you and your neighbor happy. Then; 1) Let your neighbor know you have a problem with their current venting system and ask if they will alter it satisfactorily. 2) If they seam hesitant or unsure how to proceed, offer the information you have and the name of a contractor. 3) If they balk at the cost, or just flat refuse for another (any) reason, offer to pay for it yourself.
I remember reading of someone who had neighbors who's exterior lighting was quite annoying. They paid for replacement fixtures and an electrician to install them. Peace in the neighborhood.

[Chris Weekly]

Got to drive up the hill, over the top, then down that winding street (like all tourists did) - Lombard Street ( https://blog.parkme.com/2013/04/02/lombard-street-parking/ ).

Yeah, heck, I've been on that a dozen times - its not just tourists who do that. I can't imagine what the homeowners must put up with - why would anybody in their right mind want to live on that street with all the traffic? Just to say 'I live on the windiest street in the world'.