Maximum height of bathroom drain under open "vanity"

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sillycat41

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Hello - I can't seem to find a definitive answer to mu question. I am going to install a sink in a counter top between two cabinets so the plumbing will be exposed underneath. To minimize the view of the pipes I want to put the drain/p trap as high as I can. For a 36" high counter and a 6" deep sink... how high can I attach the waste T fitting??

Also found this paragraph confusing. Why does the sink drain have to be situated below the water supply lines??

"The water supply line runs out of the wall into a hole in the back of the vanity, typically placed at a height of 22 to 24 inches from the finish floor. The sink drain is then situated just 4 inches inward from the water supply line. The drain line for the sink is centered inside the vanity cabinet about 3 to 4 inches inches below the water supply line."

Please advise. Thanks!
 

Terry

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The water supplies can be anywhere in the cabinet.

The allowable height of the drain depends on the drain. Is it a push-push from the top? Does it have a pop-up with pivot bar?
Assemble the drain to your basin and take a measurement.
 

WorthFlorida

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To get the trap as high as possible this style of a P trap will work. There are several manufacturers of them so prices and finishes will vary.
033056687512.jpg


https://www.lowes.com/pd/American-S...CQRdmpC8p485JkorLa4aAnAJEALw_wcB&gclsrc=aw.ds
 

sillycat41

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The water supplies can be anywhere in the cabinet.

The allowable height of the drain depends on the drain. Is it a push-push from the top? Does it have a pop-up with pivot bar?
Assemble the drain to your basin and take a measurement.


Thanks for the quick reply. I haven't purchase the under-mount sink and laminate countertop yet. I'm just finishing the wiring and plumbing so that I can put up the dry wall. I was thinking of having the drain opening at 24" from the floor... that should allow enough space to hook up the P trap to the sink, correct? Can't imagine it would need more than 12". ??
 

Reach4

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Those are really nice but unfortunately I'm retired and on a tight budget.
You think those are nice? You have to have the santee perfectly centered on the sink drain. So I think it would be a PITA. But if you really think such a thing is desirable, search for "bottle trap". You can find cheaper ones.
 

Jeff H Young

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better too low than too high. but even better to be perfect. 18 inches isn't that low if its already built. if you are wanting to bust wall open and move your lines. and do a pretty job . 24 probably a good height
 

Terry

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My standard rough for a 36" high lav counter has been 22" from the floor.
Though plus or minus some also works.
I used to do 18" for lav counters when they were lower.

k-9033-cp-01.jpg


There is no left/right adjustment with a bottle trap.

A new counter on an old rough-in height.
 

Jeff H Young

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If you have the time and the parts are all there lay it out on floor. it wastes time but you'll get it right
 

Moira

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I am having a similar issue. My vanity has a shelf. I could plumb either below or above the shelf. I chose to plumb above the shelf. I raised the drain line in the wall to 22" so I could get the drain line and the ptrap all to fit above the shelf.

I don't have the countertop or the sink yet. They come together. (Undermount sink quartz top).

The top of the vanity is 33.5 inches. If the sink is 7" deep, will I be OK? I am calculating 3.5" from the sink drain hole to the halfway point of the drain line in the wall. I did this myself. Getting ready to close up and this was a total surprise to me. I didn't think about that. I have a reason but hey I'm a girl. Nough said there. Please help me!
THANK YOU
 

WorthFlorida

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I am having a similar issue. My vanity has a shelf. I could plumb either below or above the shelf. I chose to plumb above the shelf. I raised the drain line in the wall to 22" so I could get the drain line and the ptrap all to fit above the shelf.

I don't have the countertop or the sink yet. They come together. (Undermount sink quartz top).

The top of the vanity is 33.5 inches. If the sink is 7" deep, will I be OK? I am calculating 3.5" from the sink drain hole to the halfway point of the drain line in the wall. I did this myself. Getting ready to close up and this was a total surprise to me. I didn't think about that. I have a reason but hey I'm a girl. Nough said there. Please help me!
THANK YOU
Using a bottle trap as shown above and as Terry mentioned, the sink drain and wall drain must be near dead on straight. With a regular p trap for a bathroom sink it gives some more wiggle room if the two do not line up.

But first, will the sink have an overflow? A seven inch sink is the inside depth, not necessarily the outside bottom of the sink. An overflow may add another two inches. After adding the tail piece to the drain, then the p trap. You may be more than the 10.5" you're hoping for. You might want to buy a trap and a sink drain. Assemble it on the floor and do some measurement. Bottle traps will give you the most height but they can be expensive.
 

Tuttles Revenge

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All measurements need to account for whether the cabinet sits ON the Finished floor or the Rough floor. From that finished height you need to measure down from the point that the sink mounts to the counter top.. either above or under. What type of drain assembly will be used? A push/pop up style has the least length to accommodate a higher rough in. This part is hard to estimate without having the actual fixtures so here is where Fudge Factor comes into play. The trap has to fit under the pop up assembly so give yourself an inch or two under the best guess of the pop up height.

I draw out all of these dimensions on a large full sized cardboard with all the components drawn in to ensure I get accurate measurements.
 

John Gayewski

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Are we're just hoping to breeze past the fact that bottle traps aren't legal? Or good.
 
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