single to double vanity conversion on second floor, venting solution?

[mdb06]

Thank you to all who moderate and contribute. I'm seeking a solution to the following DIY project. It is the second floor master bath and I am converting the single vanity to a double vanity. See photo to see the current plumbing/venting. Issue: I am trying to figure out out how the right-side vanity will be able to drain toward the left, PAST the vent for the 1st floor kitchen sink, and how the venting should be laid out. I know I cannot drain the right-side vanity into the vent for the 1st floor sink. I'm wondering if I can re-route the kitchen sink vent as far right as possible at an angle, UP, then back left, thereby "boxing out" room for the right-side vanity. I am concerned with having to create too many cut outs in the framing. The red ovals are approx location of the vanity sinks.

Of note: I'm pretty sure the vanity vent and the kitchen sink vent join higher up this wall, as there are is only one stack vent I can see in this area of the roof.

 

[Jeff H Young]

drain the lav on the right under neath the cabinet kick over to the other lav easy enough I see no holes need be made except putting a santee low enough over at the left lav might take a little cutting in the bottom plate

 

[Sponsor]

 

[mdb06]

Thanks Jeff. I need to dissect your recommendation. You suggest the right sink would have its own P trap and then flow at gradient to connect below the left sink saunter with its own santee? And in order to get that new santee low enough I might have to open up the existing opening in the bottom plate? My two concerns are the style vanity we have (three middle drawers) and having room under the vanity for the new runouts for double vanity hot&cold water valves. The drawing attached was my guess at a solution. Figured the vent for first floor sink could take multiple 90 degree bends.

 

[Jeff H Young]

another way is too offset the lower sink vent down kinda low like 10 inches above floor so that the new lav drain can cross and tie into the existing with a santee around a foot off floor all the pipes will be in the wall a few 90s on the venting but no big deal actually easier than my first idea. No attached drawing did i see?

 

[mdb06]

Thanks for checking in again Jeff! My issue was trying to attach too large of photo file sizes. Also, I had a few distractions recently...in the past 72 hours, I became a dad! Life is good...and this project will be calling me back to it in due time.

Here is the drawing that never uploaded, and sounds very similar to your proposal. I've also attached a photo to show the exact ABS plumbing, as I expected. I will make measurements of vanity to see exactly where the center-line of each vanity sits in relation to ABS drains/vents, and may have to move the original 1-sink vanity drain pipe slightly right with a 45deg fitting (see drawing). I think the vent for the 2nd vanity could either be as shown in drawing, or the vertical vent could be directly next to the current 1st vanity vent...or code may allow it to tie directly to the 1st vanity vent with a "double fixture fitting" and not require it's own vent. The project will also include modifying current 1/2" pex hot/cold water lines to two sets of stub outs with valves. Just want to make sure I'm meeting codes. I believe there are required height offset above vanity top to horizontal vents (to avoid back up and overflow) as well as maximum runs for horizontal drains (in this case, right-side vanity sink to original drain) before independent vent is needed.

 

[mdb06]

Here is a sketch of the other options, as described above. Note: if my vanity specs allow, I will not mess with shifting the current vanity drain left or right if I don't have to.

 

[Michael Young]

Thank you to all who moderate and contribute. I'm seeking a solution to the following DIY project. It is the second floor master bath and I am converting the single vanity to a double vanity. See photo to see the current plumbing/venting. Issue: I am trying to figure out out how the right-side vanity will be able to drain toward the left, PAST the vent for the 1st floor kitchen sink, and how the venting should be laid out. I know I cannot drain the right-side vanity into the vent for the 1st floor sink. I'm wondering if I can re-route the kitchen sink vent as far right as possible at an angle, UP, then back left, thereby "boxing out" room for the right-side vanity. I am concerned with having to create too many cut outs in the framing. The red ovals are approx location of the vanity sinks.

Of note: I'm pretty sure the vanity vent and the kitchen sink vent join higher up this wall, as there are is only one stack vent I can see in this area of the roof.

View attachment 98601

make your life easy man. just use an end outlet waste and catch both drops with tubular. Same with the water. Put a splitter on the hot and cold and just pull some long supply tubes to catch the faucets. "Gosh darn golly" boring and notching and all that nonsense. It's a freakin’ vanity. You're already increasing pipe diameter from 1-1/4 to 1-1/2. It'll take every every bit of volume you throw at it

 

[mdb06]

Thanks for your suggestion Michael. I’m all for making life easier. Below is a picture of the vanity we purchased. I’m trying to picture how your suggestion would work when there are drawers in the middle, blocking the vanity drain pipes you linked (end outlet pipes). The only thing I can imagine is going under the vanity/above the tile, , which makes me wonder how the P traps will work, and what interference will be with water lines (even if I just have the one hot and one cold).

I had a slow leak from the old p trap, rotting out the subfloor with mold, so I figured easier to just cut it out and start fresh.

 

[Michael Young]

Thanks for your suggestion Michael. I’m all for making life easier. Below is a picture of the vanity we purchased. I’m trying to picture how your suggestion would work when there are drawers in the middle, blocking the vanity drain pipes you linked (end outlet pipes). The only thing I can imagine is going under the vanity/above the tile, , which makes me wonder how the P traps will work, and what interference will be with water lines (even if I just have the one hot and one cold).

I had a slow leak from the old p trap, rotting out the subfloor with mold, so I figured easier to just cut it out and start fresh. View attachment 98686

well damn. my suggestion isn't going to work with this particular vanity. You're going to have to knock a couple of holes through your studs and plumbing it the traditional way. I would suggest you use a tee instead of a cross. or at the very least install a wall cleanout where you have access to service the drains. Some of these guys will use a cross. but if you have a clog, your cable just travels straight across and its a major pain in the ass to service. I typically use two stacked sanitary tees and pull my stubout (not to dead-center). I typically put my stubout for the drain aprox. 2-3" off-center of the cabinet space. You trap has a swing of 3.35". going off-center just gives you a little more room. Makes it easier on the trim-out in my opinion.

I stub my drains out at 16-18" off the finished floor.
I stub my water lines out at 20-22" off the finished floor.

 

[Jeff H Young]

Id go with something similar to drawing in post 5 but instead of the double fixture fitting Id stack 2 santees

 

[mdb06]

Thanks for the votes on how to plumb the vents and drains. Is the reason for preferring the stacked santees versus double fixture strictly due to less trouble with clean out? If I did add a clean out, does it go below the stacked santees/ double fixture?

The water lines throughout the house (toilets and sinks) come up through the floor. I’m not sure why. But I know in this bathroom it’s because the wall is an exterior wall and I get freezing winters. So I will need to stub out from between the joists , which is now Exposed and easy to work on.

Thanks Michael for the measurement guide to stub outs.

 

[Michael Young]

Thanks for the votes on how to plumb the vents and drains. Is the reason for preferring the stacked santees versus double fixture strictly due to less trouble with clean out? If I did add a clean out, does it go below the stacked santees/ double fixture?

The water lines throughout the house (toilets and sinks) come up through the floor. I’m not sure why. But I know in this bathroom it’s because the wall is an exterior wall and I get freezing winters. So I will need to stub out from between the joists , which is now Exposed and easy to work on.

Thanks Michael for the measurement guide to stub outs.

Yes. the only reason I avoid using a double sanitary tee is because I want the pipes to be serviceable. It sucks when you cant get t the drains because the cable passes straight across instead of going down. That's why I stack instead of using double sanitary tees.