How many bath fans are required?

[Robert Ellenberg]

Saw a plan today with a variation on what we called a "Hollywood bath" 30-40 years ago. A shared tub/shower combination entered from either side through a half bath. However, the half baths both have a door that separates the toilet compartment from the sink/vanity area. So on each side you enter from the hall into a 3'x5' area with a sink vanity, through a door into the toilet compartment and from each side a door from the toilet into the shared tub area.

Question: disregarding that their can be a couple of windows, does each separate compartment need ventilation since it can be closed off from the other compartments by doorways--5 fans or 3 plus 2 windows?

 

[mark handler]

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.Each room, which the shower opens into, but one vent will work

 

[pyrguy]

Robert

La still on the '06 Codes?

I'll have to look at the books for IRC but the IMC states,

"401.2 Ventilation required. Every occupied space shall be

ventilated by natural means... or by mechanical...

IIRC, (I haven't done residential in almost three years) residential reads almost the same.

So, NO fans are not required. IF natural ventilation is used.

Be sure to read the section on openings between rooms with natural ventilation.

" 402.3 Adjoining spaces... the opening to the adjoining rooms shall be unobstructed

and shall have an area not less... than 25 square feet (2.3 m2)..."

Normal doors do not have the required sqft area.

Quotes from 2006 IMC COPYRIGHT © 2009 by INTERNATIONAL CODE COUNCIL, INC.

 

[Jobsaver]

Disregarding the windows as advised, you need three individual fans since each of the water closet compartments are separated from the shower area by doors. The doors constitute obstructions between adjoining spaces.

 

[GHRoberts]

Do the plans show the doors being open or closed?

During the inspection process were the doors open or closed?

If the doors are removed, would you approve a single fan?

If the doors had self opening hinges, would you approve a single fan?

---

I would prefer several fans, but I have no way to ensure that the fans are used.

 

[pyrguy]

They do make exhaust fans that have multiple intakes. Ever heard of whole house vent fans?

So one fan of the proper design and installation will work.

 

[Jobsaver]

Agree with Dwight. A single fan with multiple intakes will work in lieu of three individual fans.

 

[Robert Ellenberg]

Thanks for the opinions and input. In posting my question I had not thought about the fan with multiple inlets as I have not used one.

I was already assuming the toilet rooms and tub area would need ventilation (3) outlets of some arrangement. The new twist (I should have been more specific) is that the area with the sinks are separate areas and would they need a fan as well (total of 5 outlets)?

 

[peach]

If there are doors, each compartment needs a fan. The toilet compartment has always been a mystery to me, since there is generally not moisture to be removed (the real reason for the fan... not potential smells). The moisture is the real threat to the building, not the smell.

 

[Sandman]

Peach you are correct. I presented this as a code question in October 2008 and this was the response;

Code Question:

Code Edition: 2006 IRC

Code Section: R303.3 & M1507

Code Question:

Where a bathroom group consists of a bathtub/shower combo and a vanity with an adjacent toilet room separated by a door, is one exhaust fan near the bathtub/ shower sufficient?

The exhaust fan meets the 50 cfm intermittent requirement.

We currently have two exhaust fans operating in an Energy Star/LEED certified dwelling, one near the tub/shower and the other in the toilet room.

When the door is closed and both fans are on, the room is placed in negative pressure. This is creating a problem for us from the humid air in the attic above.

The bathroom group to include the toilet room is 62 square feet.

Answer:

Section 303.3 in the 2006 IRC requires ventilation in both bathrooms and water closet compartments. In the case that you have described the water closet is in a separate compartment and would require a separate exhaust fan. The remainder of the bathroom would also require a separate exhaust fan. I hope that this answers your question. If I can be of further service feel free to contact me.

This information is based on information you have provided. We have made no independent effort to verify the accuracy of this information nor have we conducted a review beyond the scope of your question. As this information is only advisory, the final decision is the

responsibility of the designated authority charged with the administration and enforcement of the code.

Bob Guenther

Sr. Technical Staff

ICC / Architectural and Engineering Services

5360 Workman Mill Road

Whittier, California 90601-2298

Ph 1-888-422-7233 (ICC-SAFE)

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Email: bguenther@iccsafe.org

The International Code Council (ICC) Plan Review Services staff of

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Please contact us the ICC Plan Review Services Department at 1-888-ICC-

SAFE (422-7233), extension 33809, or visit the ICC website at

www.iccsafe.org/cs/techservices

 

[technomaze]

Disregarding the windows as advised, you need three individual fans since each of the water closet compartments are separated from the shower area by doors. The doors constitute obstructions between adjoining spaces.

GREAT ADVICE