View Full Version : Standard for kitchen supply and waste height off floor?

May 10, 2007, 03:44 PM
Is there a standard height off the floor for the cold/hot water supplies and the waste pipe or drain (the part the P trap goes into).

I ripped out what was there before as the sink was a long distance from the waste pipe (terminoloy?) and the pitch was towards the sink and not the drain.

I was thinking about 19" off the finished floor for the supplies and 12" for the drain?

The kitchen sink will be an undermount either 9 or 10" deep.


May 12, 2007, 07:41 AM
The standard rough in for a kitchen sink is 18" off the floor to the center of a 2" stub-out. The water lines rough in at either side of the stubup. Good luck, Tom

Aug 31, 2008, 10:20 AM
The response listed above is just plain wrong. When installing a deep kitchen sink, especially with a garbage disposal, the rough-in needs to be lower. From my recent experience with this, it seems like 12" would be the proper height. BTW, I am completely dismayed at how many plumbers I asked didn't know the proper answer to this question. The plumber who roughed in my sink also stated the usual 18" rough-in, and then set the rough-in at 17" even after I quizzed him about whether this would be right with a deep sink and a garbage disposal. He said that he needed to do it at that height for code compliance. Yesterday, he installed the sink hook-ups and the p-trap is so high that the waste pipe from the disposal goes uphill instead of downhill. After he left, I went online and found out that the disposal specs call for a 4" drop from the waste pipe to the top of the p-trap. Now I am scratching my head and asking myself why I hired a so-called expert plumber to plumb my sink instead of just doing it myself. : (

Aug 31, 2008, 11:25 AM
The response listed above is just plain wrong. When installing a deep kitchen sink, I'll go along with that, (But you didn't have to get so snotty about it.) For a deep sink 14" sounds about right. However, most sinks aren't "deep sinks" and they rough in at 18" with no sweat. But wait! The question was
Standard for kitchen supply and waste height off floor? STANDARD I believe is what he said.
Since when is a deep sink considered standard? So you got all pissy with me for nothing. Standard sinks run between 6 1/2 and 9 inches deep with a deep sink running about 13 3/4". How deep is yours?

after I quizzed him about whether this would be right with a deep sink and a garbage disposal. He said that he needed to do it at that height for code compliance. Never heard of that code before. I agree the plumber should have listened to you when you said "deep sink" instead of stubing out for a regular. In short the plumber should have paid attention and checked the depth of your sink before he stubbed out. Bad plumber! But don't take it out on me because I answered the question correctly as it was asked. Had the question mentioned a deep sink I would have answered differently. But it wasn't and I gave the correct measurements.
I bet you'll be outraged to learn that back before disposals, PVC, Ice makers,etc. that our kitchen sinks roughed in a 21" from the floor to the waste stubout. Of course our sinks were all cast iron With 8" tubs back then. Since this is your first post, ( and you certainly impressed me ) welcome to AskMeHelpDesk. Tom

Aug 31, 2008, 12:14 PM
Yes, you are correct that I didn't need to be so snotty. Mia Culpa! I'm sorry to have let my frustration at this one particular plumber overflow and stink up this forum... especially on my first post. The sink that was installed by the countertop company (part of a package deal) was 10 inches deep, and I have an Insinkerator Evolution Cover Control garbage disposal. So, the sink is not as deep as what you mentioned to be deep dish sinks... looks like it is somewhere in the middle. Regardless, with an 18" stub out, it is not possible get any of the 4" drop from the disposal to the top of the p-trap that is referenced in the garbage disposal manual.

So, now I am wondering just how bad my situation is. As it is installed right now, the waste pipe from the disposal to the p-trap is exactly level (i.e. no grade at all), and that waste pipe is about 1/2" above the level of the stub. Is a 4" drop form the waste pipe to the trap really necessary, or should this installation work OK the way it is?

Thanks in advance for your input and, again, sorry for being snotty earlier.

Aug 31, 2008, 01:10 PM
It is not uncommon for folks to run into trouble especially with a deep under counter sink installions with dispoasls. I have this situation all the time and frequently install a S trap and an AAV, both can be out of code in some areas. The old standard is what Tom listed and why not, between the two of us we are approaching 150 years. The newer sinks, under counter sink and disposals did not exist 40 years ago and still don't affect most folks. The 2009 plumbing code will likely take all of this into account. They are even changing the size of drains to washing machines because the newer ones over power a 2" drain. Also, your slope should be 1/4" per foot.

Aug 31, 2008, 01:50 PM
Is a 4" drop form the waste pipe to the trap really necessary, or should this installation work OK the way it is?
I don't have a disposal ell to measure but as I recall they aren't much over 4 inches themselves. Did the manufacture say why a 4" drop was necessary? Your man put you in a tight job but unless you have backfall from the trap to the stubout, head pressure and the centrifugal thrust of the table should let you drain OK. If it bothers you why not cut the disposal ell back a tad and raise the trap to give you some fall? And don't sweat the attitude, we get it all the time. Good luck, Tom

May 30, 2011, 05:50 PM
Good thing I found this site before stubbing out. I was going ahead with about 12" above floor height ,but wanted to make sure . I have a disposal going in and a 10" under-mount sink so I guess I was doing it right but its Now confirmed

Milo Dolezal
May 30, 2011, 09:47 PM
It depends what kind of sink you will be using. Also, if you are using Garbage Disposer.

With 10" deep sink and GD, rough-it in as low as possible - which is about 10"-12" from the floor. ( Don't forget, there will be 4" kick plate and actual stub-out will be 6"-8" above the cabinet floor ). So after all is installed, the bottom of the trap will be almost touching bottom of the cabinet.

Good luck with your project. Let us know how it went. Milo

Apr 16, 2012, 10:08 AM
I have an 11" deep Kohler cast iron "deep" kitchen sink with a Kitchen Aid g/d. My rough in is at 18" and every thing fits fin and has worked flawlessly for 10 years... no back-ups, no clogs, nada! I've seen a few super-low-stub installations, (fact, am working on one right now), the only thing I see is that it makes the necessity of extra extensions, and it's a pain to work around. I've installed numerous Stainles Steel Deep sinks and have never needed to be lower than 14", most of the time the 16"-18" has been fine. I don't know where you guys are getting the 10 to 12" from, unless you're meaning off the floor of the cabinet... which blue prints almost NEVER use that dimension reference pt.

Mar 4, 2013, 01:20 PM
For Kitchen sinks I usually install the drain at 10" to 14" depending on sink depth and disposal.For bath vanities I use 16"to 18". Because of the varying depths of sinks I require the sink on site prier to Rough-in. For supply lines (Hot/Cold) I set them 2" to 3" above and 4" of center of drain. I am not a "plumber" but remodeling is how I make my living. It is also my requirement that cabinets and fixtures be on site or a cut sheet/drawing be available

Dec 9, 2014, 07:15 PM
Just another non-standard situation to keep in mind. I have run into several problems with standard drain heights in recent years when replacing cabinets and counters to the lower accessible height of 34-1/2".

Dec 9, 2014, 07:22 PM
Has anyone noticed this thread was started in 2007? New member,please take note of the posting dates. It is common for very old threads to come back alive for little good reason.