Updating existing plumbing for wider kitchen window

[MikeCO]

I am going to be updating the plumbing in our kitchen for a remodel due to a larger kitchen window being put in. I have full access underneath (see this post for what it looks like) and am going to be taking down the kitchen walls to the studs, so I have a lot of room to work.

I'm trying to see what my different options are since my walls are 2x4. The one thing I do know is that I won't be able to use the existing vent location since the engineer doesn't want me to go through the rafters (it's a vaulted space), and I wouldn't have room to go horizontal above the window if that was even an option structurally.

I am checking with the engineer to see if it is possible to go through the king/trimmer studs to the right of the window with structural bracing, so for now, trying to understand all of the options. I'm okay to put another penetration in the roof if necessary and/or just a better design.

My understanding of what options I would have:

In the basement, angle the drain/vent to the right by a couple of feet and have it go vertically next to the window, new vent penetration through the roof
- Kitchen sink AAV, drop the drain down into the basement and connect over to the new stack
- Kitchen sink loop/island vent
- Combination waste/vent an option??

I also posted a top-down picture of how the stacks come into the basement. If I'm using two AAVs for both the laundry sink in the basement and the kitchen sink, is the vertical vent even doing anything? I don't know 100% where the floor drain ties in but it almost seems like the 2" stack ties into the main drain system upstream of the floor drain.

 

[wwhitney]

CO uses the IPC, which permits AAVs. As long as elsewhere in the DWV system you have a vent through the roof, you can use an AAV on the kitchen sink, and then you don't need any vent piping above the AAV, in particular nothing above the elevation of the countertop.

Island sink venting is not an option, as you do not have an island sink.

If you want to have a vent through the roof to the right of the window, you could bring the trap arm out of the wall to avoid the king and jack studs. You could run the trap arm through the carcass of that drawer bank to the right of the sink base, and just make one of the drawers 3" shorter than the others. Or you could make the whole drawer bank 3" less deep, which is simpler but wastes a bit of space.

Doing something similar on the left side would require making the countertop 2-3" deeper, because of the dishwasher. That would be a more radical change.

Cheers, Wayne

 

[Sponsor]

 

[MikeCO]

Thanks Wayne. If I go the AAV route and remove the higher vent piping, is that still okay with the floor drain? That was throwing me off but is that vented from the other stack?

 

[wwhitney]

The information you provided on the floor drain and how it is connected is insufficient to say whether it is vented properly.

However, if the kitchen sink vent does play some role in the proper venting of the floor drain (would not be true of the typical methods of venting, but could possibly be true of one of the less common methods I'm not as familiar with), changing that kitchen sink vent from a vent through a roof to an AAV would not affect the validity of the floor drain venting. (Fairly sure I know enough about those less common venting methods to say that.)

Cheers, Wayne