Drain line: going from 1 bathroom sink to 2

Users who are viewing this thread

French_guy

Member
Messages
58
Reaction score
1
Points
8
Location
Michigan
I'm having my bathroom floor being redone (vinyl to tile)
I'm removing the current vinyl, underlayment and single sink vanity myself. Since we will have a new (and nice) floor, we were thinking replacing the single sink vanity by a double one.
How should I plumb the waste line? Is the only option to open the wall, or can I do something "easier"?
I have something like this (not my picture, but very similar)
bathroom.JPG

Can someone point me to pictures/links/information (something easy to understand.....I'm not a professional plumber ;))

Thanks
 
Last edited:

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
double_lav_rough_1.jpg

To do it correctly, the drain and vent piping in the wall will need to be changed to meet the new sink.
People have a tendency to focus on connecting the drain, but a proper vent connection is just as important.
 

French_guy

Member
Messages
58
Reaction score
1
Points
8
Location
Michigan
Distance between the 2 sinks (center to center) will be 48”….Is it too long for 1 p-trap only and one arm from 2nd sink to 1st one?
 

French_guy

Member
Messages
58
Reaction score
1
Points
8
Location
Michigan
double_lav_rough_1.jpg

To do it correctly, the drain and vent piping in the wall will need to be changed to meet the new sink.
People have a tendency to focus on connecting the drain, but a proper vent connection is just as important.
What should be the max distance between each stubout and the vertical vent pipe? The one on the left is longer that the right....
And what if my studs are 2x4 (exterior wall, ~30 years old house)?
 

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
42" max between the trap and vent for 1.5" trap arms.

We would drill the framing and install stud shoes to reinforce the studs. The insulation goes back in on the outside of the drain piping.


If you want to hack the back of the vanity, the drains can be inside the cabinet, and a pair of 1/8th bends can be used to get the vent back in the wall.
 

French_guy

Member
Messages
58
Reaction score
1
Points
8
Location
Michigan
Looks like in the wall is the best solution
Distance between my 2 sinks is 42", but won't be centered on the existing stub-out. The right sink will be at 32", the left at 10" (see picture, the blue tape represent the axis of each sink)
So I would have to cut open the wall, cut the existing stack and install a double sanitary tee.....then should I use a flex coupling to attach the top of the sanitary tee back to the vent line?
I've heard stub-out are usually offset from the sink, it makes the connection of the p-trap easier.....How much should be that offset?
And what is the standard height of a stub-out?
Thanks
 

Attachments

  • IMG_1457.JPG
    IMG_1457.JPG
    51.9 KB · Views: 176

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
Start by opening up the wall to see what you have to work with. The drain that is there could be going left, right, or down inside the wall.

Ideally, the drain in the wall is going down.and is 2" so that you can use a double fixture fitting, not a double sanitary tee.

I don't know what you mean by "flex coupling". If the piping is galvanized, you can use mission couplings to tie in your new work.

The best height for the stub-outs depends on the height of the cabinet and the depth of the sinks.
 

French_guy

Member
Messages
58
Reaction score
1
Points
8
Location
Michigan
This is what I have
On the right, I need to open 1 more cavity....
On the left, the center of the sink is right at the stud level. So I guess I will have to have an offset, but at least no stud to drill
 

Attachments

  • IMG_1522.JPG
    IMG_1522.JPG
    88.2 KB · Views: 176
  • IMG_1523.JPG
    IMG_1523.JPG
    108.8 KB · Views: 534
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks