bath fans with opening windows

[howardrichman]

Builder is telling me ; there's a new building code that requires an exhaust fan in baths, even if windows that open and have easy access. Is this so? Also if large bathroom has separate toilet room, is only one fan required over the toilet?

HR...

 

[cowboyjwc]

Yes there is a new, three year old code (or six year old, depending on which code cycle you're on). It's in the Mechanical code.

 

[david luchini]

Yes there is a new, three year old code (or six year old, depending on which code cycle you're on). It's in the Mechanical code.

Which section of the Mechanical Code requires exhaust fans in bathrooms?

 

[mgookin]

Builder is telling me ; there's a new building code that requires an exhaust fan in baths, even if windows that open and have easy access. Is this so? Also if large bathroom has separate toilet room, is only one fan required over the toilet?

HR...

You're not saying if you're half bath or full bath in 1&2 Family, multi-family, transient residential, or a locker room in a gym, etc. More info gets you a better answer every time!

Generally you need exhaust for steam and for stink. That segregated toilet area needs a dedicated fan. You still need a fan for a shower.

 

[renosteinke]

Let's have some citations, please. The 2006 IRC (International Residential Code) allows a 1.5 sq. ft. window to meet the requirement. The 2006 UMC (Uniform Mechanical Code) does not address this question at all. (IRC 303.3) The UMC does discuss some related issues (504.1)

Any fan use needs to exhaust at least 50cfm- AFTER taking into account duct materials, length of run, and bends. I'm not sure I've ever seen an original bath fan installed that meets this flow requirement. There should also be some slope to the duct, so that condensation will drain outside.

I am not sure, but I think the CFM figure is for a 'normal' bath (one toilet, sink, & shower). I believe additional shower heads and fixtures can require a greater cfm.

 

[cowboyjwc]

Well he doesn't say where he's from, but it's in the CA Residential Code section R303.3.1 and the CA Building Code section 1230.4.2.1. I know, I said Mechanical Code.

 

[jxofaltrds]

Builder is telling me ; there's a new building code that requires an exhaust fan in baths, even if windows that open and have easy access. Is this so? Also if large bathroom has separate toilet room, is only one fan required over the toilet?

HR...

He must have read it on the internet. So it is true.

Some res. code:

303.3 Bathrooms. Bathrooms, water closet compartments and other similar rooms shall be provided with aggregate glazing area in windows of not less than 3 square feet (0.3 m2), one-half of which must be openable.

Exception: The glazed areas shall not be required where artificial light and a mechanical ventilation system are provided. The minimum ventilation rates shall be 50 cubic feet per minute (24 L/s) for intermittent ventilation or 20 cubic feet per minute (10 L/s) for continuous ventilation. Ventilation air from the space shall be exhausted directly to the outside.

303.4.2 Exhaust openings. Exhaust air shall not be directed onto walkways.

1507.1 General. Where toilet rooms and bathrooms are mechanically ventilated, the ventilation equipment shall be installed in accordance with this section.

1507.2 Recirculation of air. Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms and toilet rooms shall not discharge into an attic, crawl space or other areas inside the building.

 

[GoldDigger]

He must have read it on the internet. So it is true.

It depends, or course on where he is and what code cycles and amendments are in effect.

For example, the City of Spokane, while referring to the IRC and Washington State Energy Code.

states in a summary concerning additions and remodels

A new bathroom or one that has had
the ceiling opened, or if an existing bathroom does not have an exterior window, it must have a minimum 50 CFM exhaust fan vented tothe outside with a positive connection tothe outside. I

That implies to me that the absolute fan requirement applies to entirely new construction as well. I am still looking for the ultimate source of that though.
The 2012 IRC does not appear to require that, and I have not found anything newer.

Similarly the 2013 California Green Building Standards Code contains the following:

4.506.1 Bathroom exhaust fans. Each bathroom shall be mechanically ventilated and shall comply with the following:

This is not an optional Green certification code but rather a mandatory code for all state regulated buildings (Feds are exempt!) and specifically includes:

All residential buildings constructed throughout the State of California, including but not limited to, hotels, motels, lodging houses, apartment houses, dwellings, dormitories, condominiums, shelters for homeless persons, congregate residences, employee housing, factory-built housing and other types of dwellings... [and so on for another whole paragraph....]

It is effective Jan 1, 2014 so it might be the sort of thing the OP heard about.

 

[howardrichman]

Well he doesn't say where he's from, but it's in the CA Residential Code section R303.3.1 and the CA Building Code section 1230.4.2.1. I know, I said Mechanical Code.

Thanks for replies;
I'll be ventilating the toilet room; not sure if needed in rest of bath, even w/shower stall

HR...

 

[GoldDigger]

It depends, or course on where he is and what code cycles and amendments are in effect.

For example, the City of Spokane, while referring to the IRC and Washington State Energy Code.

states in a summary concerning additions and remodels That implies to me that the absolute fan requirement applies to entirely new construction as well. I am still looking for the ultimate source of that though.
The 2012 IRC does not appear to require that, and I have not found anything newer.

Similarly the 2013 California Green Building Standards Code contains the following:


This is not an optional Green certification code but rather a mandatory code for all state regulated buildings (Feds are exempt!) and specifically includes:

It is effective Jan 1, 2014 so it might be the sort of thing the OP heard about.

Just a bit more on the subject:

The California variation on the IRC (2013 California Residential Code) contains this added section:

R303.3.1 Bathroom exhaust fans. Each bathroom containing a bathtub, shower or tub/shower combination shall
be mechanically ventilated for purposes of humidity control in accordance with the California Mechanical Code, Chapter 4; and the California Green Building Standards Code, Chapter 4, Division 4.5.

Note: Window operation is not a permissible method of
providing bathroom exhaust for humidity control.

Now this does not apply to bathrooms in which you cannot bathe! So toilet and sink only rooms are not covered by this particular provision.
It makes some sense that an open window can provide odor control ventilation, but if at a normal height will not do a lot to exhaust steam or moisture unless you also leave the door open.

PS: Here is another real winner in the CalGreen:

All permanently installed lighting in bathrooms shall be controlled by a vacancy sensor.
Exception: One high efficacy luminaire with total lamp wattage rated to consume no greater than 26 watts of power.

But that one, for now, is voluntary.

 

[howardrichman]

This job is in New Jersey. Not sure if the bath fan requirement varies in different states. There's a separate toilet room, and big bathroom w/ a basic tub, and shower stall. Do I need additional fans other than the toilet room? There are opening windows w/ access. if I need multiple fans, I'm considering do go with Fantech w/ multiple vents and high CFM fan in attic.

HR...

 

[Gregg Harris]

This job is in New Jersey. Not sure if the bath fan requirement varies in different states. There's a separate toilet room, and big bathroom w/ a basic tub, and shower stall. Do I need additional fans other than the toilet room? There are opening windows w/ access. if I need multiple fans, I'm considering do go with Fantech w/ multiple vents and high CFM fan in attic.

HR...

2012 International Energy Conservation Code
R403.5 Mechanical ventilation (Mandatory).
The building shall be provided with ventilation that meets the requirements of the International Residential Code or International Mechanical Code, as applicable, or with other approved means of ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.

IMC TABLE 403.3 MINIMUM VENTILATION RATES
Toilet rooms and bathrooms<sup>g

g. Mechanical exhaust is required and recirculation is prohibited except that recirculation shall be permitted where the resulting supply airstream consists of not more than 10 percent air recirculated from these spaces (see Section 403.2.1, Items 2 and 4)</sup>

 

[GoldDigger]

2012 International Energy Conservation Code
R403.5 Mechanical ventilation (Mandatory).
The building shall be provided with ventilation that meets the requirements of the International Residential Code or International Mechanical Code, as applicable, or with other approved means of ventilation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.

IMC TABLE 403.3 MINIMUM VENTILATION RATES
Toilet rooms and bathrooms<sup>g

g. Mechanical exhaust is required and recirculation is prohibited except that recirculation shall be permitted where the resulting supply airstream consists of not more than 10 percent air recirculated from these spaces (see Section 403.2.1, Items 2 and 4)</sup>

The way I read the IECC section, if the IRC applies the IMC does not, since it says OR not AND???
In that case for residential, the IMC footnote requiring a fan would not apply as long as there is not a similar provision in the IRC?
Or does the IRC incorporate that part of the IMC?
Too many cross-referenced codes. <sigh>