Need help with Vanity Plumbing

[Jakester]

I am upgrading from a single sink (30" vanity) to a double sink (60" vanity) my question is how to run the plumbing the correct way? In the attached pictures you can see where the only sink was, the second sink will be to the right of that one. I need to keep the plumbing in the wall because I won't be able to run inside or underneath the vanity.

 

[FullySprinklered]

The vertical pipe is being utilized as a vent for a downstairs fixture, though it's tied in a bit low. Should be at about 46 inches off the floor to be legal.

You need to cut the vertical pipe fairly close to the floor and install a tee. You need to clear the nails holding the stud to the floor plate and you'll be ok when you drill across to the new vertical pipe.

Reconnect the original vertical pipe by whatever means necessary and raise the downstairs vent connection to legal height.

Drill across to roughly center of the two lavatories and 90 up into a cross maybe 16 inches off the floor. Send out two trap arms right and left to the new lav locations. A little off center of the middle of the bowls is good enough. The trap can swing.

Continue up and take a left and drill across back to the original vent to allow you to reconnect to the vent.

Piece of cake.

Don't leave much wood, does it?

 

[Sponsor]

 

[Michael Young]

locate the wall cleanout at 8" to center. it hate using a cross. instead, I rough the lavs in using one tee facing one direction and a second tee facing towards the other sink. I despise snaking a line and having the snake walk across the cross.that's why I rough in double lavs using two santees instead of a cross.

 

[hj]

Leave what you have for that sink. Install a tee lower, go to the right, turn up behind the sink with a tee, then reconnect to the vent at least 42" above the floor and connect that existing vent at the same level.

 

[Jakester]

Thanks guys! What size pipe is best for this?

 

[Terry]

For two lavs, 2" and then each individual lav can be 1.5"

 

[Jakester]

what about if I cut the 90 out install a wye on its side with a street 45 then continue it with the next sink with a 90, would that work or is that a no-no

 

[hj]

A no no,because the second sink will flow past the first one without proper venting.

 

[FullySprinklered]

Sorry, kids. I like my way best for this particular job.

 

[Jakester]

I modified my picture and attached.

fullysprinklered this is that your talking about?

 

[Jakester]

Does it look right the way I drew it on the picture?

 

[Terry]

Does it look right the way I drew it on the picture?

As long as the vent back to the stack is at least 42" high.

 

[Jakester]

42" high from the floor or drain (split)?

 

[Jakester]

or does this look better?

 

[Terry]

Santees on the vertical, combos and wyes on the horizontal.

 

[FullySprinklered]

I modified my picture and attached.

fullysprinklered this is that your talking about?

Sometimes how you run the piping depends on the parts you brought with you. On new houses, I would buy parts that I thought would be needed, plus boxes of parts left over from previous jobs. The scenario that I presented was just the first thing that popped into my head. There's a lot of things to think about including cabinet drawer location, etc. A lot of people in the construction trades are comfortable leaving unresolved issues for the next guy. I always asked a lot of questions of the contractor and the customer to help get it right the first time, if possible. There's several ways to get it right, in other words.

 

[Jakester]

do i keep it 42" high from the floor or drain (split)?

 

[Reach4]

do i keep it 42" high from the floor or drain (split)?

floor.

 

[Jakester]

I attached some pictures. The 1st one is how it is now, picture 2 and 3 is what I was thinking about doing, what do you guys think will be better? Sorry for all of these questions, I not a plumber but I am a DIY'er but want to do it right.

 

[Michael Young]

I attached some pictures. The 1st one is how it is now, picture 2 and 3 is what I was thinking about doing, what do you guys think will be better? Sorry for all of these questions, I not a plumber but I am a DIY'er but want to do it right.

First - if you put TWO MORE GIANT HOLES through those studs, what's going to hold the wall up? I would cut out the old 90 for the single lav. Use a coupling and glue on a piece of pipe. Glue in a 2" combination and lay it on it's side (facing out) to catch the first lavatory. Then I would keep going with that 2" pipe and install a 2" 90 (like what you already have to catch the second lav.) I would get my air by installing an air admittance valve underneath the furthest basin and let that studor vent catch both sinks. Simple and fast