Kitchen sink vent questions

[Bull0117]

Hello,

I'm remodeling my kitchen and we've put a large window, 6ft wide, above where the sink will be. This involves me redoing the vent and this is where I'm looking for some advice from people who've done this more than me. You can see in the first diagram below where things are currently, the old vent dropped straight down and served both the kitchen sink and the utility room below but not through a wet vent, it tee'd off at roughly window sill height then went to the kitchen sink and utility room below separately.

See below for what I'm thinking is a viable option, excuse the crude drawing My biggest challenge is that I cant get 42" above the floor with the vent before going horizontal, it's close but not quite. I'm also planning on using stud shoes where I have to drill through the studs, which lowers the horizontal part of the vent a little bit more. I'd have to ask my inspector if they'd allow it to not be quite high enough. This is all 1.5" PVC and is a remodel, going to 2" would be tricky where it drops through the floor as it's inside another wall that I'd rather not demo.

All this a bad idea? Any other thoughts about how to do this?

Thanks!

 

[Reach4]

Picture!!! Great to see that working.

Split the vent at least 6 inches above the flood level of the sink off to the right of the window. Then bring that split dry vent down and over and down. A wye feeding a 45 would be elegant splitting, but an inverted santee feeding a 90 out the side would be quite OK.

 

[Sponsor]

 

[wwhitney]

I would say that if the connections through the bottom plate are not moving (*) and if the vent under the rough opening sill is actually above the sink flood rim (bearing in mind the height constraint of the stud shoe), even if not the full 6" above, then the benefit of only drilling the double jack and king studs once is greater than the benefit of optimizing the vent paths by drilling it twice. Also, drilling the double jack and king studs at a 45 degree angle is out of bounds structurally.

In other words, the routing drawn is the best option I see within the various constraints. As for drilling the double jack and king studs, you can use a Simpson HSS2-3-SDS3 for (3) 2x studs. Installation will require removing and replacing the stud to right.

Cheers, Wayne

(*) The window is wide enough that the strategy of putting the san-tee to the right of the window, and passing only the trap arm through the double jack and king studs won't work, as MN uses the UPC, which limits a 1-1/2" trap arm to 42" in length.

 

[Bull0117]

Thanks for the replies guys. I spent some more time going through this and I'm reconsidering using a stud shoe. I don't need to bore the tripled stud more that 60%, which is code, so I don't actually need one. Without the stud shoe I'm able to get the horizontal part of the vent close to the sill which puts the pipe centerline at 41.25" above the floor. Still doesn't quite meet code but I'm going to send my plan to the city and ask for an exemption. Seem reasonable?

 

[wwhitney]

Thanks for the replies guys. I spent some more time going through this and I'm reconsidering using a stud shoe. I don't need to bore the tripled stud more that 60%, which is code, so I don't actually need one.

I don't believe that is correct. The reference is IRC R602.6.2 which for MN may be seen here (along with an accompanying diagram):

https://up.codes/viewer/minnesota/irc-2018/chapter/6/wall-construction#R602.6

In particular, R602.6.2 says:

"Drilling. Any stud shall be permitted to be bored or drilled, provided that the diameter of the resulting hole is not more than 60 percent of the stud width, the edge of the hole is not less than 5/8 inch (16 mm) to the edge of the stud, and the hole is not located in the same section as a cut or notch. Studs located in exterior walls or bearing partitions drilled over 40 percent and up to 60 percent shall be doubled with not more than two successive doubled studs bored. See Figures R602.6(1) and R602.6(2).

Exception: Use of approved stud shoes is permitted where they are installed in accordance with the manufacturer's recommendations."

So since you are going through 3 studs, the allowance in the main paragraph is not sufficient, and you need to use the Exception.

Cheers, Wayne

 

[Bull0117]

I see what you’re saying. My understanding, which may be wrong, is that cripple studs under a window are generally not considered load bearing and wouldn’t be counted as one of the load bearing studs being bored. Might have to ask the city about that one…

 

[Jeff H Young]

no plumbing code that I know of allows connecting 2 vents less than 6 inches above flood level Upc never allows it but upc can allow offsetting the vent horrizontally less than 6 inches above flood level in a situation like this.
why not move both pipes to the side of the window and run trap arm over to the sink under cabinet ? or what about an AAV?

 

[Bull0117]

Hey Guys, my updates seem to take a long time to post but thanks for your thoughts. I spoke with my city building inspector today, sent him that drawing from a few posts up and told him I'd be right at about 40" when I turn horizontal. He said they'd be OK with that as long as I get it up as high as I can.

 

[Jeff H Young]

right cripples have almost no load . if inspector is ok good i guess you can proceed as you wanted