Can you vent through an exterior wall rather than the roof?

[JoAndo]

We bought an old timber house and there is a single exterior 2” vent for the second floor. It’s attached to the house and stops right under the eaves.
The 3” drain that services the upper floor is 42’ long and has no other vents. There’s a full bathroom at the far end of the house, a kitchen in the middle, a laundry and another full bathroom at this end (close to the existing vent). To make matters worse, the bottom floor kitchen and bathroom is venting straight into the second floor, not to exterior. So my questions are:

1. should I merge the bottom floor vents into a single and make the exit at the top of the upper floor wall?
2. is the existing exterior vent sufficient for all those fixtures?
3. must I go through the roof?

TIA for any input.

 

[Tynyyn]

As per code:

Min 6" above roof (&12 in. to vertical surfaces in UPC)
Min 7ft. if adjacent walking area (within 10 ft. UPC)
Min 4 ft. (10 ft. UPC) when directly below building openings, & min 3 ft. above openings within 10 ft. horizontal
Min 6 in. above snowline (10 in. above roof as per AHJ UPC)

Item 3 is what meets your needs. As I read it the pipe can be a minimum of four feet below a building opening and three feet above openings within ten feet of the horizontal.

So in essence you can put a vent pipe out the side of your dwelling as long as it is four feet below a door or window AND/OR three feet above a door or window as long as it is ten feet away from the door or window on the horizontal.

So the vent has to be four feet below a window and/or it has to be three feet above a window and ten feet away from it.

Check the IPC and UPC Chapter 15 for full explanations. Do not rely upon me. I am not a professional nor an amateur, I'm just a regular Joe who has an abbreviated copy of the UPC and IPC building codes.

 

[breplum]

Plumbing vents must be above roof line.
As far as adequate vent, the UPC states that the vent area must equal the largest required building drain area. In many cases 3" is the size of a drain and any combination of areas can equal the 3". (ie: two 2" and one 1-1/2")
However, I have read articles by plumbing engineer that make the case for more limited venting working fine on a practical basis.
The code is designed to be foolproof and guaranteed to protect traps and health. That is the gold standard. We see so much bad plumbing in foreign less-developed countries.

 

[Zanne]

Yes, you can put the vent pipe through the wall instead of the roof but you need to extend it around and above the eaves. This is how it is done on my house. It goes up toward the eaves then has an ell to go out and around and then back up again.

 

[JoAndo]

Thanks all. Cayman adheres to the 2009 International Plumbing Code. I have a copy of the 2018 code but still can pinpoint the correct section in it. Anyway, my reason for asking was that I’d like to have the least number of holes in the roof as possible. Although going out of the was and then through the eaves would work, it is not as aesthetically pleasing as stopping at the wall.

 

[Zanne]

Going around the eaves will likely be easier than going through the eaves. You can't terminate below the eaves. I wish I could find the picture of my setup where it went around the eaves. It's not pretty, but better than nothing.