Kitchen sink DWV on exterior 2x4 wall, under window

[Gslenk]

I am trying to plan moving kitchen sink to under a window on an exterior wall with 2x4 framing. Attached is a layout of the structure, and where existing stack/drains are.

In addition to "what are my options?", I was originally planning on 2" drain pipe for the kitchen sink/disposal, but disposals have a 1.5" discharge, and I am assuming I'm gonna want the pipe to be smaller to facilitate tucking/routing/small bore holes/etc... So also, "am I making too much of a sacrifice going with 1.5 pipe instead of 2 inch pipe?".

I'll have to explain some things in the diagram:
*Rectangle under sink is an HVAC floor supply register (to be extended under/out of sink cabinet) the remainder of the joist bays should be free and clear of major obstructions.
*Small rectangle on the left is the footprint/location of original sink rough in area
*I highly suspect the 3" cast iron stack/vent (to be replaced with pvc) is between the studs where text is.
*The black circle is where the drain stack is in the basement (not in the wall, behind the wall over by a few feet)
*The other side of the interior wall is a bathroom, its plumbing is both in the interior wall, and under the floor.
*Dishwasher will go to left side of sink
*floor joists are 2x8, all walls are 2x4 studs, everything is spaced 16" OC.

I know I cannot bore through exterior studs (at least not enough to fit 1.5", let alone 2" drain pipe). I'd also like to avoid furring out the exterior wall, reducing cabinet depth, or running a chase on the basement ceiling, although it does seem like at least one of those may have to happen. I'm hoping there is a simple solution that I missed.

All I have so far is 45 over to exterior wall (green), bore/notch through window cripple/king stud. Not sure what else happens after, or even if that is a decent start.

 

[WorthFlorida]

This is what you can use for horizontal runs through wall studs. https://www.homedepot.com/p/Simpson...Galvanized-Stud-Shoe-for-2x-SS1-5-R/100375338

Maryland uses IPC plumbing code and it requires 2" waste line, and the vent must be no more than 5 ft from the kitchen sink trap. https://codes.iccsafe.org/content/IPC2015/chapter-7-sanitary-drainage

https://www.co.lincoln.or.us/sites/..._-_helpful_hints_residential_construction.pdf

 

[Sponsor]

 

[Gslenk]

Gotcha. Well then 2" it is. so that shoe would allow me to notch a load bearing stud beyond what code allows? The studs are 3.5" wide, 2" pvc is about 2.5" that would be at least 70% of the material of the stud gone. I think code allows for 40%, on exterior walls.

 

[Tuttles Revenge]

Your horizontal trap arm which will be drilled through the wall will only need to be 1.5" pipe. That trap arm connects to a 2" drain no further than 5ft from the trap to the point where its vented. The connection from Horizontal trap arm to the drain could be a vertical drop to your joist bay. In that configuration you wouldn't need to drill the 2x4 studs for any 2" pipe.

 

[Gslenk]

I think I've got my head somewhat wrapped around this. Red line is 2" drain/stub out. Green is 1.5" vent. Seems like the standard approach.

Now how do I go about getting past the window king stud? Beef it up and put in a 2" hole, "simpson strong tie/etc"? Or is this configuration not allowed, and I should route the vent "around" the jack/king studs (see another picture I stole). Just found out what a dirty arm is, I don't think I want to do that.

Also, although I have the patience to run the drain through perpendicular joists below, (in a bunch of little segments) is that a bad idea with all those joints?

I would be tempted to run the drain in the cavity to the left of the window, and run the trap arm over to the sink, however, the dishwasher will be to the left of the sink, and I think those take up the full space of their spot.

 

[Tuttles Revenge]

Drill the stud. Repair with the things if you feel you must.

Drilling thru joists is fine, assuming 16" layout each pipe segment is 30" depending on how deep below the top you go. You could also travel through the toe kick of the cabinetry starting with the top of the fitting barely under the bottom of the kick then strapping to blocks to slope down to the joist bay you want to get to.

 

[Gslenk]

This is the wall/window in question. Window will be raised to a few inches above counter level. I'll try to slope the vent pipe, but I won't be able to get 45+ degrees to make it "vertical". Also, anything above a few degrees for rain water would likely give me too large of a hole (oval) anyway.

The king studs for this window are doubled by original construction. Does that mean I get a 60% allowance on boring holes, or am I still stuck at 40% unless I add additional studs? Or just bore through them anyway?

 

[Tuttles Revenge]

The vent is fine being horizontal. Anything from 6" above the flood level and down needs to be sloped 1/4per ft like drainage, and long sweep fittings from vert to horz. Medium sweep 90 from horz to vert.

I don't know the specifics for drilling off the top of my head.. Adding an extra stud won't hurt anything, but I don't see anyone on our projects need to repair that hole even if its technically beyond capacity.

 

[Gslenk]

Gotcha. At least the trap arm and vent plan can be checked off...

 

[Gslenk]

So through joists is not an option. The required slope will not allow enough horizontal length.

As an alternative to putting a chase on the basement ceiling, how does this plan look?

2" 45 degree into fur out "yellow to red" (only behind cabinets, wall above cabinets remains 2x4)
Green will be the vent, that angles up into original wall cavity.
Red drain continues in fur out, then long 90 into interior non bearing wall (to orange)
Bore through interior wall studs (two of them) use HSS shoes to get back some rigidity.
Tie into 3" drain/vent stack blue.
** The blue stack goes horizontal, with a horizontal cleanout (purple) then finally drops to below slab sewer line.

Does the yellow 45 help me avoid a cleanout on this drain, or did I exceed 135 degrees when I tie into the 3" vent/stack?

 

[Gslenk]

OK, I think I found a decent solution. Hope the pictures do the explaining part well. Any problems, or room for improvement? Gonna overhaul the adjacent bathroom while I'm at it, turns out there are two s-traps in that bathroom

A few questions, brief explanations:
Shower: 2" drain, 1.5" vent tied into 3" vent stack.
Can I orient the p-trap the way I have it? Can I hack the shower dry vent any which way to snake around stuff as long as it is within 45 degrees of vertical? Can I use a normal wye clocked upwards to start the vent? Do you recommend I downsize to 1.5" for the drain, or keep it 2" if I can make it work?

Bathroom Lav: 1.5" drain
I know I might exceed the max 42" trap arm on the lav, if so, I plan to add a relief vent, 1.5". Could it be a 1" vent? I want to minimize boring out studs...

Kitchen sink: 2" drain, 1.5" vent horizontal around window, then up to attic to tie into 3" vent stack.
I think a clean-out is a good idea, having a hard time deciding between pictured layout (maybe on top of santee instead, if it fits), or right after p-trap, before the santee drain drop.

Let me know if I need to clarify anything. I tried to avoid a wall of text.

 

[Tuttles Revenge]

The tub and shower traps would both need to be vented separately from each other and each drains connection downstream of the vent connections. And the Tee connection that the tub is currently connected to the 3" needs to be a Wye fitting. Kitchen sink run looks good, tho I would suggest to have your cleanout above your sink drain connection (my drain cleaners preferred method) and it can be a tee or a wye. Bath sink extension is fine, as long as its vented within 3ft6in of the trap (one of the s-traps you're fixing is assume?)

 

[Reach4]

Kitchen sink vent should stay vertical 6 inches above the flood level of the sink. 45 is considered vertical.

 

[Gslenk]

The tub and shower traps would both need to be vented separately from each other and each drains connection downstream of the vent connections. And the Tee connection that the tub is currently connected to the 3" needs to be a Wye fitting.

Maybe that picture is misleading, it will be one single drain. I mocked up the new plan next to existing (which may have made it look like two p-traps), which will all be ripped out and replaced. It is a bathtub/shower combo, one drain (with overflow attached to drain). It is currently s-trapped, and uses a santee to tie into the drains (wrong on both accounts). I will convert to the appropriate wye+45 for whatever it ties into, and send a vent up after the trap arm before the drain goes downward, then tying into the rest of the drains. I will have to get creative on this vent to clear obstructions down low, so I was mostly asking if I can do whatever I want as long as it stays above 45degrees from vertical. IE multiple 22.5's or 45's to snake it over where I want it to go straight up.

Kitchen sink run looks good, tho I would suggest to have your cleanout above your sink drain connection (my drain cleaners preferred method) and it can be a tee or a wye.

Makes sense. I was thinking of that as an alternative. The wye seems like a pain to cover/finish, I would prefer an "access tee" or santee, or other low profile cleanout if it makes no functional difference for ease of access, and cleaner install/drywall etc.

Bath sink extension is fine, as long as its vented within 3ft6in of the trap (one of the s-traps you're fixing is assume?)

Yup the S part of the S-trap was hidden in the wall (p-trap into wall, then drop without venting, then over = s-trap). I think I can keep it under the max length to avoid a relief vent. Otherwise, upsize the pipe, or relief vent here I come.

Does the 3" waste/vent stack count as a vent for the WC? The only waste heading down the 3" "vent" above the clean-out would be the bathroom lav.

Also, I am a little cramped on space so does the overall order of connections to the drain pipe look good? sink and shower will be individually/relief vented.

 

[Gslenk]

Kitchen sink vent should stay vertical 6 inches above the flood level of the sink. 45 is considered vertical.

I'll have to double check my cabinet measurements to see if I can move over that far. If so, then great, I'll 45 up from the adjacent cavity (45 wont work from current cavity). If not, I have been lead to believe a horizontal (but sloped) dry vent isn't that great of a sin. Perhaps I have been mistaken?

I can see a backup leaving deposits being a problem with a horizontal vent under the flood level. If I must go that route, would a two-direction clean-out above the p-trap santee bail me out?

 

[Reach4]

https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Also, the santee could be in the cavity left of the window, and the trap arm could go horizontal to an elbow under the window. With 2 inch pipe, the path within the pipe from the santee to the trap could be up to 8 ft. (page 2 of that link)

Like this, but without the laundry standpipe:

I think the green is discussion of where to put a cleanout.

A 2x4 outside wall seems totally inadequate for plumbing and insulation. You could bring the pipes into the space under the sink, as in the photo above, rather than putting them all in a 2x4 wall.

 

[James Henry]

https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Also, the santee could be in the cavity left of the window, and the trap arm could go horizontal to an elbow under the window. With 2 inch pipe, the path within the pipe from the santee to the trap could be up to 8 ft. (page 2 of that link)

Like this, but without the laundry standpipe:

I think the green is discussion of where to put a cleanout.

A 2x4 outside wall seems totally inadequate for plumbing and insulation. where the toilet was upstream of the shower and where theirs no mention of the toilet being down stream of the shower? Well, That's what Ive been talking about.

https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Also, the santee could be in the cavity left of the window, and the trap arm could go horizontal to an elbow under the window. With 2 inch pipe, the path within the pipe from the santee to the trap could be up to 8 ft. (page 2 of that link)

Like this, but without the laundry standpipe:

I think the green is discussion of where to put a cleanout.

A 2x4 outside wall seems totally inadequate for plumbing and insulation.

Did you see the drawing in the brochure in the wet vent section where the toilet was upstream of the shower and theirs no mention that the toilet had to be the farthest fixture downstream? This is what I have been trying to get a conclusive answer on.

 

[Reach4]

Did you see the drawing in the brochure in the wet vent section where the toilet was upstream of the shower and theirs no mention that the toilet had to be the farthest fixture downstream? This is what I have been trying to get a conclusive answer on.

I see it on page 12. They increased to 3 inch, it seems that does it for IPC.

 

[Tuttles Revenge]

I think we're straying off target for this thread.. but shouldn't the H-vent drawing have a 2" vent? Unless the IPC allows 1.5" vents for toilets?

And I'm pretty sure the notion that toilets be the most downstream fixture is from some crazy idea that toilet waste needs other fixtures to wash down the drain.

 

[Reach4]

I think we're straying off target for this thread.. but shouldn't the H-vent drawing have a 2" vent? Unless the IPC allows 1.5" vents for toilets?

Page 2 of that IPC document says

Remember, the vent size is not based on the trap or fixture drain (trap arm), but the drain
size that continues downstream from the point where the vent and fixture drain connect.
The drain size is determined by the fixture unit load in accordance with Tables 709.1,
709.2, 710.1(1), and 710.1(2) in the IPC. Hence, if the drain size is 4 inches (102 mm),
a 2-inch (51 mm) vent is required. A 3-inch (76 mm) drain would require a 1½-inch (38
mm) vent. A 2-inch (51 mm), 1½-inch or 1¼-inch (38 or 31.8 mm) drain would require a
minimum 1¼-inch (31.8 mm) vent, this being the minimum size allowed.​