What's in a name.... Bathroom

[Eric H.]

DIYer here... in the middle stages of designing a custom home in Auburn WA. I know that the local inspector will have the final word but wanted some other perspectives.

Q: What exactly is a bathroom? Specifically - our new home design (and our current home) utilize a master "bathroom" where the vanity sink/dressing area is in a separate area (w/ door) from the combined "wet" area that contains the toilet, bath, and shower. We favor this design for a number of reasons.

When looking at the mechanical ventilation requirements of the 2018 IRC (and I believe the Mechanical Code as well), my architect stated quite confidently that we would need to have TWO separate bath fans (one for the vanity area and another for the "wet" area --- or at least an inline fan that serviced both areas independently.

This seems a bit overkill to me since the vanity area really has no major source of humidity or odor... but when I look through the IRC, etc. I actually don't see a clear description of exactly what a "bathroom" consists of. I had thought that (perhaps) the two rooms together could be considered the "bathroom" but the architect stated that the presence of a door in between negated that idea.

So... if someone has a lavatory sink in their bedroom (the old wash stand) does this mean it has to be re-designated as a bathroom too? We actually have the same bathroom configuration for the family bath area as well... so now we are talking about having to have another two fans just to service that fairly small grouping as well.

Just curious if I just have to roll over on this one or are there some other sources of info that I can attempt to use to bolster a different viewpoint.

 

[Terry]

That's a good question, and now I want to know more. I don't recall ever seeing a second fan for a vanity before.

I found this link, but it doesn't really say what becomes a bathroom either.

https://www.kitchensource.com/bathr...l9H6TP_YsDUuyyOqFJHcAV97ivUliwPM#:~:text=1.,2.

Though if it's required for a powder room then it would make sense that the area with the bathroom sinks may need it too.

EXHAUST FAN REQUIREMENTS
(Reference Table 3-1):
a) Bathrooms, laundries, and powder rooms: 50 CFM @ 0.25” W.G.
b) Kitchens: 100 CFM @ 0.25” W.G. Range hoods and down draft ranges shall be rated not less than 100 CFM @ 0.10” W.G. 2.

EXHAUST DUCT REQUIREMENTS:
a) Be insulated to a minimum R-4 in unconditioned spaces.
b) Be equipped with a backdraft damper.
c) Terminate outside the building.
d) Comply with Table 3-3 and section 303.3.4.

 

[Sponsor]

 

[Jeff H Young]

some of your codes only went into effect Feb1 2021 maybe this is one of them . and your in designing stages? would explain why we haven't seen them in such a way. interested to hear as well on the topic

 

[Eric H.]

The architect says it has been this way "for many years -- since they first started specifying mechanical ventilation requirements for bathrooms". But I don't know how much of this is based on his own interpretation/ his experience with certain inspectors versus it actually specifying this as a requirement somewhere (which I can't find). Given how many different ways a "bathing area" can be built, I'm surprised that I can't find a more specific definition of "when is a bathroom really a bathroom".

 

[Eric H.]

I know this question is a bit out of scope for this forum. I was going to post this question on a "mechanical/hvac forum" somewhere but couldn't really find one that seemed to have the same level of activity as this place.

 

[Eric H.]

@Terry - Thanks for the link. I guess when I consider a powder room it normally also has a toilet... so I can see why you would want ventilation. But for a compartment that just contains the sink (or even 2 sinks) it just seems to be a waste. Oh well... I will keep looking. It's interesting how we all take terms for granted (e.g. bathroom, powder room) and then get flummoxed when it comes to actually defining what is and is NOT meant by the term.

 

[Themp]

You need to talk to an inspector for your area/city and see what they say. When we had an architect draw up plans for our house there were many things that were specified in the plans that were just there to make sure the architect could not be liable. Things like basement block and how it had to be strengthen, steel beams across open areas, to framing requirements that were overkill. And an electrical plan that the electrician basically threw away. We loved the design of the house but when it came down to how it was to be implemented some things were overdone.

 

[Jeff H Young]

Themp got a good idea but if plans call for it and you dont build that way could be a problem.
I dont like to ask an inspector if I can do something, What if he too is wrong? or if he tells you one thing the 6 monthes or a year later when actualy do the job that inspector isnt on your job?

 

[Themp]

I just had a case where I replaced the furnaces in the house. The HVAC contractors would not re-use a chimney flue in the attic furnace. They said it was against code now and I had to punch a hole in my roof for a stove pipe type vent. I just went to my city's website for inspectors and send an email off to the head of the department. They came back saying it was fine to re-use the vent, along with the requirements for doing so. Once I had this on paper from them, no contractor gave me any trouble, other than one just flat out said they would not do it. So, you do need something on paper. Email your inspection department with the above information and see what you get back.

Finally, I assume you are going to have a builder/contractor build your house? If so, this can also be addressed to the builder. The builder is usually much better versed on what is real than an architect. Now if your architect is your builder, I guess you are stuck. In the end, you can always remove the exhaust vent in the dressing room and sheet rock it over. Or, get one that also puts out heat and then you can keep this room nice and toasty in the winter.

 

[Jeff H Young]

Themp that sounds like a better idea than just asking an inspector , plus remember not all inspectors are knowledgeable, nor contactors, or any of us.
I also think this shouldn't be a mystery and likely resolved very quickly , if its a room with no door open to say a bedroom that has a window I would expect it ok, but HVAC out of my scope other than piping them

 

[Kreemoweet]

For what it's worth, my copy of the National Electrical Code (which is by no means current, but I doubt
this part has changed) defines "bathroom" as an area that has a basin, and one or more of:
a toilet, tub, or shower.

 

[wwhitney]

Perhaps more on point, the IMC defines a bathroom as "A room containing a bathtub, shower, spa or similar bathing fixture." And a toilet room as "A room containing a water closet and, frequently, a lavatory, but not a bathtub, shower, spa or similar bathing fixture." The mechanical ventilation requirements in IMC 403 are for bathrooms and toilet rooms.

So under the IMC, a mechanical ventilation requirement is not triggered by a lavatory only. As the IRC is silent on the definition of bathroom, I would think it eminently reasonable to defer to the IMC requirements.

No mechanical ventilation required for lavatory only.

Cheers, Wayne

 

[Jeff H Young]

Nothing wrong with asking architect to clarify.

 

[Eric H.]

@wwhitney -- Thanks for pointing me to the IMC (which I did not have access to at the time). At least this gives me a solid definition upon which to start a discussion with the builder/inspector/etc. They might or might agree but it is a good place to start the discussion. Thanks all!

 

[Tuttles Revenge]

The potential for humidity from a lavatory sink or two seem low to me. We don't have fans to draw the humidity from a kitchen sink / dishwasher. We put them in places where prolonged hot water is going to be used. Bathrooms (tubs / showers) and laundries... and toilets.

But maybe bathroom sinks do produce more humidity than what we imagine tho.

 

[Jeff H Young]

If speced out on plans to have the fan and plans go through plan check is it still ok to delete if in fact there is no code requiring it? don't the documents become the deciding factor. either the code or approved plans whichever is more stringent.
Thays why I thought discussion with Architect might be in order as opposed to asking inspector if you can disregard plans . So I don't really know proper way to go about it. but if I'm paying Architect Id like to build my house my way and if my way is wrong than show me why I'm wrong. I don't mind being wrong if they will tell me why

 

[LLigetfa]

Specifically - our new home design (and our current home) utilize a master "bathroom" where the vanity sink/dressing area is in a separate area (w/ door) from the combined "wet" area that contains the toilet, bath, and shower.

Does not code require a sink near the toilet to wash your hands?

 

[Tuttles Revenge]

Does not code require a sink near the toilet to wash your hands?

What is your definition of near? His bathroom suite has sinks, they're just not attached to the toilet like a prison toilet.. or maybe even within view. A handsink in a restaurant kitchen is 25ft from a work station. In many airports I've used theres a bank of toilets and urinals with a bank of hand sinks quite separated.

Didn't find any particulare requirements in the UPC or in the RCW (revised code of Washington.. law)

But did find an interesting site that may shed some light on this particular subject.
https://www.crddesignbuild.com/blog/residential-bathroom-code-requirements-design-tips

15. Ventilation
IRC

• Minimum ventilation for the bathroom is to be a window of at least 3 sq. ft. of which 50% is operable, or a mechanical ventilation system of at least 50 cubic feet per minute (cfm) ducted to the outside.

NKBA

• An exhaust fan that is vented to the outside of your home should be placed in each bathroom.
• If your shower compartment or WC is fully enclosed, they are considered their own room and should have their own exhaust fans.

So maybe, because of the separation, a second fan is required?