What separation is required between a bath vent & kitchen vent. Code question.

[TheOverThinker]

Hi there;

I have a planned remodel, with a bathroom and kitchen in close proximity, each of which will need a vent.
This is in California, so the California Mechanical Code (IAMPO UMC based) and California Residential Code (CRC) apply, along with the local energy code.

Question 1: I know that each of the vents must terminate on the outside wall, at least 3 feet from the operable portion of a window. But can the two vents be next to each other? What code section covers this exact situation for clearances of two similar vents, if any?

Question 2: The building is existing non-conforming with a 2' and 3' setback (where 3' is required in this area). Will I be allowed to place the new vents on the 3' property line wall, in this circumstance?

 

[wwhitney]

Question 2 is a zoning question, so you'll have to look at Berkeley's zoning code for guidance. That's not a question I've looked into before.

As for question 1, sounds like you know which codes to look through. I find up.codes convenient for reading them.

Cheers, Wayne

 

[Sponsor]

 

[TheOverThinker]

Question 2 is a zoning question, so you'll have to look at Berkeley's zoning code for guidance. That's not a question I've looked into before.
As for question 1, sounds like you know which codes to look through. I find up.codes convenient for reading them.
Cheers, Wayne

Indeed, I've read the code and... am having trouble interpreting it for this situation. Thus the request for help.

For the clearance to the property line, it's Oakland not Berkeley and... and I already know Oakland zoning does not care. There are hints in the code about distance to the property line that again, I've tried to read but ended up muddled on the mind after. So in fact it's building that will care, if anyone does.

 

[wwhitney]

Indeed, I've read the code and... am having trouble interpreting it for this situation. Thus the request for help.

Ah. The CMC is not my forte but if you point me at the particular section that seems to apply, I'd be happy to give you a semi-informed opinion. Presumably somewhere in Chapter 5 on Exhaust Systems.

So in fact it's building that will care, if anyone does.

That's an interesting question, and I think it hinges on whether you have a full 3' from the property line or are just under. I refer you to Table R302.1(1) of the CRC:

https://up.codes/viewer/california/irc-2018/chapter/3/building-planning#table_R302.1-1

It says that an unrated wall at least 3 feet from the property line can have openings of up to 25% of the wall area, while one closer than 3 feet to the property can not have any. I typically think of openings as windows, but I assume that an exhaust vent outlet hood would also count (not sure of that). In which case a new exhaust hood opening would not be allowed if under 3' from the property line, and would be allowed if between 3 and 5 feet from the property line, unless the existing windows already meet or exceed 25% of the wall area.

Cheers, Wayne

 

[TheOverThinker]

That's an interesting question, and I think it hinges on whether you have a full 3' from the property line ..
It says that an unrated wall at least 3 feet from the property line can have openings of up to 25% of the wall area...

Just to make it more confusing, these same walls will be upgraded to ASTM E119 walls, per R302.1(1), and thus no longer be unrated:

 

[wwhitney]

Each of the 4 options in the left column are independent, and then you can look at the right column to see your options.

So if your wall is < 3 feet from the property line, no openings are allowed. If it's >=3 ft and < 5ft, then 25% of the wall area can have unrated openings. If it's >= 5ft from the property line, then openings are unlimited.

The choice of wall rating does not affect the above breakdown on openings allowed.

Cheers, Wayne