An undermount sink has to have a very flat rim around it to be able to snug up against the underside of the countertop. Some sinks are "dual" mount, meaning their rim is flat enough to be able to be undermounted or wide enough to provide support in a top mount situation. If your sink has a wide flat rim, like most silgranite types, then it can be undermounted.

Some top mount sinks (stainless) are bowed up slightly and need clips installed underneath them to pull them down to flattish with the countertop. Those cannot be undermounted.

live_wire_oak (My Page) on Sat, Aug 7, 10 at 18:32

"Those cannot be undermounted."

If it has a rim, I can undermount it.

Its just a matter of being smarter tan what you are working on/with.

snoonyb, by all means elucidate. :) I'd really like to know what hoops you'd have to go through to be able to get a topmount to lie flat under a solid surface countertop, be fully supported, and be waterproof.

From the Plumbing Forum:Posted by snoonyb (My Page) on Wed, Aug 4, 10 at 5:45
"I usually use 2x4's and screw from the opposite side of the sink cabinet sides, which allows the versatility of being able to easily change the sink in the future without affecting the counter top.
Set the cleats and the sink in-place and level with the rough top prior to the measuring for the counter top, to remove any confusion."

The solid surface material can then be "fitted" anywhere from the center of the rim of the self-rimming sink too just inside the sinks vertical bowl wall, (and I provide it), Polyseamseal is applied to seal the installation.

The underside of the material is smoothed where the point of seal is to be made.

OK, I see how the cleats support the sink from underneath and how maybe with Corian or some other softer workable type of counter material like butcherblock you can cut out a ridge of the under side of the countertop to be able to deal with the much taller "hump" factor that a traditional topmount stainless sink has. Cutting out a section would allow the countertop to lie flat on the sink with no ridge interfering with the seal. I still don't see how you'd be able to do that with a stone top unless you have very specialized tools that will cut granite safely. (Not that most homeowners would be able to DIY routing out of a corian top either.) You'd still have that ridge of the topmount rim to have to deal with and couldn't get a good seal or level. Unless you have other workarounds for that?

I think this is a lot of trouble to go to when a plain jane undermount sink can be had almost as cheaply as a topmount sink and that will work without having to kludge a "fix" to make it work.

"you can cut out a ridge of the under side of the countertop to be able to deal with the much taller "hump" factor that a traditional topmount stainless sink has. Cutting out a section would allow the countertop to lie flat on the sink with no ridge interfering with the seal."

But, I DONOT,DO NOT, DO NOT, do this.

This is exactly what is done:"Set the cleats and the sink in-place and level with the rough top prior to the measuring for the counter top, to remove any confusion.
The solid surface material can then be "fitted" anywhere from the center of the rim of the self-rimming sink too just inside the sinks vertical bowl wall, (and I provide it), Polyseamseal is applied to seal the installation."

This is the only additional step:

The underside of the material is smoothed where the point of seal is to be made.

"I think this is a lot of trouble to go to when a plain jane undermount sink can be had almost as cheaply as a topmount sink and that will work without having to kludge a "fix" to make it work."

And so you should dispense with a serviceable fixture and spend 2 to 3 times what a little ingenuity will solve?

Sorry! My customers get exactly what they want, and I get paid without hesitation.

franklin_2010 it Is possible to undermount any sink.
But if you need to ask then it is possible that you may not be able to do it yourself.
Finding a handyman who will do it may not be easy, either.
Some people don't like doing more than the minimum amount of effort.
If the rim isn't flat, it is more trouble than undermounting one with a flat rim.
However, it can be done.
It can easily be done if you understand that a little wood of the right shape goes on top of the bracket under the counter.

Whether it's that complicated, or whether it's more simple, the bracket support goes into the wood cabinets sides.
There are brackets that can be bought.
Perhaps someone here has kept track of the name of these brackets, or the web site.
These brackets are designed for undermounting sinks.
They are to be screwed into the cabinet sides.
Once you see a picture you get the picture.

Do not get anyone to drill the granite from underneath.
This is something which live_wire_oak already knows.
(I've read most threads here in the last two years).
The comment from live_wire_oak on Sun, Aug 8, 10 at 9:59 is all wrong.
Snoonyb corrected it.

franklin_2010 I'm sorry you only got live_wire_oak commenting and acting as though he or she didn't understand anything other than what they have seen before, and being sarcastic negative and artificially dumb along the way too. I've seen this before, from live_wire_oak. The negative spirit, the artifice, the sarcasm. So, on behalf of the forum participants who are open minded and willing to share, I apologize for this other person. Since I'm the one who sent you to the kitchen forum, I apologize. As for live_wire_oak, it's beginning to sound a lot like you are someone knowledgeable who is negative dismissive and disrespectful very often. It's happened to many of my postings. Perhaps it only skirts the rules of respect that the forum demands of all participants, but I find it unacceptable.

--

From terrylove.com :
"Amer. Std, and Kohler, as well as some generics, make undermount bracket kits. These take the form of bars supported by the cabinet sides, or front-back. They and the sink are installed before the granite. Then after the countertop is on, adjuster screws snug the sink up to the countertop ( with a bead of caulk of course.) Very easy to do, sink is extremely secure, and the sink can be removed if necessary in the future without disturbing the top."
from a Master Plumber, forum moderator, who has posted more than 6000 times

from a Master Plumber, forum moderator, who has posted more than 15000 times:
"The largest part of the price is the cost of the sink, and for that you have almost unlimited possibilities. I mount the sink into the cabinets with the rim level with the bottom of the granite. The mount can either be metal saddles with adjustment bolts to raise and hold the sink, or a wooden framework attached to the cabinets. Set the sink onto the supports, apply the necessary sealant, and then put the granite top over it. The sink can be hooked up as soon as the granite guys leave."

these two comments were found in
http://www.terrylove.com/forums/showthread.php?4406-undermount-kitchen-sink
which I foudn by typing "undermount" into the site's search field :
http://www.terrylove.com/forums/showthread.php?4406-undermount-kitchen-sink&highlight=undermount
In that thread someone provided links to the company that makes brackets.
Go and see.
At that site, many experienced plumbers and renovators have commented that ANY sink can be undermounted.
One of them is the 15000 post Master Plumber, who has more than 50 years experience.

HTH

Here is a link that might be useful: undermounting sinks, in the Plumbing Forum

I get what you're saying now about snugging the "hump" or the high part of the rim of the stainless topmount sink up against the countertop. Yes, caulk between that hump and the countertop will render it waterproof at the contact point at the install time, until time rolls around and that caulk is old and failing. Unfortunately, that leaves an 1/8" by 1" gap between the actual sink interior vertical side and the countertop. I don't consider that much of a gap to fill with caulk acceptable either functionally or aesthetically. It also will not be easy to dig that much caulk out at a later time when it begins to degrade and need replacement. With traditional undermount sinks, the high point of the rim and the contact point between rim and countertop is right at the edge of the sink's vertical side, making it much more accessable to remove and replace the very small amount of caulking needed.

It reminds me of the days of my youth and the old 1919 Foursquare we rented in the heart of the arts district. Someone had taken a beautiful old clawfoot tub and created a tiled deck around it and over the rim to be able to install shower doors. The rim of the tub wasn't flat at the edge where the tub met the deck. It was rounded, and that created a spot for a large wad of caulk to be installed by the jacklegger who did this "modification". If you never did anything but shower, it was mostly hidden from your view and your mind. If you took a tub, you were staring at the thick nasty yuck of a too large a bead of caulk. Even though we were renting, I couldn't stand looking at the mouldy mass every time I wanted a soak. So, I started to dig it out, which was extremely difficult to do due to it's location and size. It was gross. It had also failed, creating points where moisture had infiltrated the plywood of the tiled decking and sides. I'm sure someone was very happy with their "outside the box" solution to being able to use shower doors with a clawfoot tub, but they weren't in it for the long haul to see the result of their half assery.

If buying a $200 undermount sink is too onerous to consider with a new $2000 countertop, then perhaps this isn't a project to be undertaken until the proper sink type can be afforded. Being "creative" can come around and bite you in the end if you actually plan on staying in one spot long enough to assess the long term results of that kludge. I have nothing against new and innovative or budget ways in construction. I do have a problem with doing something different just for the sake of difference, or doing something that complicates something simple, or doing something cheap that is unlikely to stand the test of time.

Do it right once, and you'll never have to do it again. Do it wrong, and you'll repeat the experience (and the expense) multiple times.

live_wire_oak can you post a diagram?
"...an 1/8" by 1" gap..."

Sure. Check out the link to the PDF for these American Standard sinks. They are the same configuration, but one is designed for topmounting and one is designed for undermounting. The undermounting version has a flat rim that is designed to directly contact the underside of the countertop, right at the edge of the vertical side of the sink. You can have a slight positive reveal, with a small portion of that flat rim exposed, or you can choose a negative reveal with the countertop overhanging the sink by a bit. Either way, because the flat rim contacts the countertop at the edge of the vertical rise of the sink, you have a very small spot for a bead of caulk to finish waterproofing the install.

The topmount version has a higher ridge on the outisde rim ( the hump I'm talking about), and then an apron that is about 1/8" lower and 1" wide (at the front corner, it's even wider in back where the faucet deck is) before you get to the vertical side of the sink. If you place a straight edge across this sink, it will contact the ridge all around the outside at the point of the ridge. It will have a gap between the high point and the actual sink side (the 1/8" x 1" gap I mention). If you place a straight edge across the undermount type, the edge will contact the flat rim all the way across the sink, even at the vertical sink side. You will also notice the detail where it shows the mounting clips used to secure the sink downwardly to the countertop. Use of metal cross bracing would not allow that to happen, and many stainless sinks actually have a bit of a warped deck that won't be flat without those downward clips forcing them to be.

If you choose to kludge the undermounting of this type of topmount sink, you will have an extremly large gap to fill between the high point of the sink and the vertical side of the sink, especially in the faucet deck area. Now, if you choose to have the countertop that you place on top of the sink have a cutout area the equivalent to the size of the ridge around the sink, then you won't have the gap between sink side and mounting point I'm talking about. However, you will have an extremely large stainless deck exposed---a VERY positive reveal in other words. You won't get the sleeker look of a slight positive reveal or slight negative reveal.

Here is a link that might be useful: American Standard sinks

that was a good link. I got to see the hump and apron you wrote about.

That shape is tough to undermount. Hypothetically, if the OP had that kind of rim, they could choose to have that hump cut off. But it may be beyond the call of duty, to discuss such a theoretical case.

Many topmount sinks are made without that "hump + apron" around the rim.

live_wire_oak (My Page)
"until time rolls around and that caulk is old and failing."

I use polyseamseal exclusively and have returned to do remodels, and have found the product still flexible.
It works (is tooled) with your dampened finger.

"Unfortunately, that leaves an 1/8" by 1" gap between the actual sink interior vertical side and the countertop."

Unless you use a stainless rigid backer material.

"It also will not be easy to dig that much caulk out at a later time when it begins to degrade and need replacement."

Caulk seldom needs replacing, except from neglect.

davidro1 (My Page)
"if the OP had that kind of rim, they could choose to have that hump cut off."

I prefer to work with, as opposed to amend a product.

A very long time ago an entrepenure/inventor/experimenter and general "piddler" told me,"there are only two can'ts, if you can't cut it, you can't stay, and all those things that you think are impossible, are merrily opportunities to prove how inventive you are".

You see, its just a matter of being smarter than what you are working on, and not letting those inanimate objects get the better of you.

Yes, a stainless rigid backer 1/8" thick fills the gap properly.

It's not about being "smarter" than your materials. That's nonsense, unless your ego is way too bound up in reinventing the wheel for your own personal bragging rights. It's about the wise use of time and money. This isn't a wise use of either, even if you have an abundance of time and no money.

And I don't have any idea of your age snoonyb, but I'm surprised to see that you've never experienced caulk aging and needing to be replaced. I'm not an octogenarian by any means, but I am old enough to have had that unpleasant experience in several homes that I have lived. Time works it's destruction on all things. Caulk failing is a given---even for a good quality job---given enough of a timeline. Replacing caulk is a given. And, replacing the caulk in a sink installed the way you are indicating would not be a job I'd want to tackle. To each his own though.

live_wire_oak (My Page) on Tue, Aug 10, 10 at 9:46
"It's not about being "smarter" than your materials. That's nonsense, unless your ego is way too bound up in reinventing the wheel for your own personal bragging rights."

Interesting! Reading comprehension and short term memory loss:
"snoonyb (My Page) on Sun, Aug 8, 10 at 11:40
My customers get exactly what they want, and I get paid without hesitation."

Its about the customer achieving there goals, and do I achieve a sense of satisfaction from being inventive enough to solve these challenges, absolutely.

" It's about the wise use of time and money. This isn't a wise use of either, even if you have an abundance of time and no money."

It's obvious that you equate customer satisfaction with money, that without one you are incapable of attaining the other.
By the way, I work strictly from referrals and have never advertised.

"And I don't have any idea of your age snoonyb,"

I'm a decade or two older than you and put the bags on every day.

"but I'm surprised to see that you've never experienced caulk aging and needing to be replaced."

Do you have a back quote, or did you miss this, as well?
"snoonyb (My Page) on Mon, Aug 9, 10 at 23:36
Caulk seldom needs replacing, except from neglect."

"Time works it's destruction on all things. Caulk failing is a given. Replacing caulk is a given."

Here is a little pearl of insight for you. Being a home owner carries with it a lifetime of required maintenance and upkeep. And another. To retain the value of your investment.

Ergo, proper and timely maintenance forestalls replacement for years.

"You see, its just a matter of being smarter than what you are working on, and not letting those inanimate objects get the better of you."

Instead of becoming a victim and capitulating to the whim and fancy of others, take charge, row your own boat.

"And, replacing the caulk in a sink installed the way you are indicating would not be a job I'd want to tackle."

It's also obvious you have little understanding of the wide variety of caulk material available and their proper use for application, or you would know the workability of polyseamseal.
I've used caulk priced from $.97 to $26.00 a tube.

Broaden your horizons.

Become at least as smart as what you are working on.

"To each his own though."

It's just a matter of being smarter than what you are working on, and not letting those inanimate objects get the better of you.