If getting a new kitchen countertop installed, does the job of attaching an undermount sink fall on the countertop installed or the plumber?

The countertop installed has to attach all the clips that are typically epoxied to the underside right?

Are there clips on four sides or just left/right/back sides? My old countertop & sink does not have any front clips.

the majority of the time the countertop people install the sink and then drill the faucet hole/s on sight.
the sink should be sealed, clipped on 4 sides and not disturber for 24 hrs.

Here they don't use clips, just epoxy. The rim gets epoxied and they also use short strips of plywood which gets epoxied on to the underside of the countertop and provides extra support to the sink.The plywood gets used on kitchen sinks where the bond between the epoxy and the stainless steel is not very strong whereas the wood bonds very strongly to the countertop.

i agree, george. the strength is created by the silicone or the epoxy. the clips just hold the sink from moving until the bonding material dries.
so, i'm guessing your answer to sum is ... the countertop people install the sink....

Most countertop companies will require that you have the sink purchased, onsite, and provided to them at the time of measurement. In 2 cases we had undermount sinks, and the countertop companies took the sinks with them back to the fabrication plant. Countertop arrived with sink cutout and install prep done, sink was installed onsite and faucet holes were drilled onsite.

Our current house we went with a farmhouse style sink, and even though it's an undermount, the granite company wanted the sink installed in the cabinet base before they would come and measure for the countertops. The install was a bead of silicone around the sink rim before the counter was set in place, then faucet holes drilled.

The existing sink (which will not be reused) is attached to the countertop with 8 clips. Here are some pictures of the clips on the underside.





A close up picture you can see they made a bow tie shaped recess on the underside of the countertop. I am thinking they filled these with epoxy, then the clips were installed screwed into the epoxy?



Not sure why they made these bow tie shaped holes. But it seems these clips will be difficult to install on site if you have to flip over the countertop and wait 48 hours for liquid epoxy to set and cure.

How does one typically cut the countertop hole to match the sink's outline?

I mean, most undermount sinks I have seen, the granite countertop is flush with the sink bowl. Like below, the edges of the countertop match the inside rims of the sink bowls.



However, the new sink I am going to use, comes with a cardboard template.





If you cut the countertop hole using the template, it will result in the countertop hole being 1/4" larger then the sink all the way around, like below. It seems weird to cut an oversized hole like this because if you wiping down the counter with some bread crumbs or whatever debris they will all be collected at the top edge of the sink that will need to be cleaned off again. I wonder if I should ignore the template and just have the hole cut to match the edges of the sink?

sum... do a google images search for "granite countertop stainless sink". you will quickly see sinks installed both ways. i would just let the countertop people install the sink the way they normally do.

Packy I did that but my searches I saw most had the countertop cut out matches the sink's rim or even overhang a bit, the ones that has the sink and top edges exposed seem to do that because they need the extra ledge because the sink comes with accessories like cutting board, wash basket or rinsing rack that sits on those ledges.

I think with a reduced cutout it's easier to clean, you wipe bread crumbs or olive oil into the sink instead of that ledge? Plus it gives the sink top edges a larger surface to apply sealant or adhesive?

Sum, that's why on a stone countertop the fabricator will request that the sink be onsite when they measure so they can address these questions. The sink cut out is usually done by CNC water jet these days. When they are onsite to measure, they use a series of laser targets and a laser measuring machine that creates a file that is uploaded into the CNC water jet. It looks like on your existing countertop, they cut the sink and added the epoxy bowties so they could screw into the stone. Those are cured before the top is delivered so the sink can be installed easily onsite.

As Packy says, once you contact a countertop company they will answer all your questions.

Don,

I already have a countertop fabricator, they are coming tomorrow to make the template.

I have the new sink on site. Undermount SS double bowl Elkay ELUH311810.

I have the new faucet on site.

I have the cardboard template that comes with the sink. This cardboard template is sized such that it results in a 1/2" reveal of the top of the sink all the way around.

The fabricator on the phone said "it is a matter of preference if you want to use the template we will use the template". So it's back on me to make a decision.

My wife feels a 1/2" reveal all the way around creates a ledge. So you wipe down the countertop whether it's bread crumbs or tomato seeds or spilled milk all that gets collected at the ledge then you have to wipe down the ledge so she thinks if the sink overhangs it is more practical.

As for me, I think an overhang cut out reduces the size of the hole, which mean the countertop is less likely to break/crack during transportation or when they drill the faucet hole. I also think a small overhang means if there are some unforseen situations that forces the sink to be mounted slightly off like 1/8" more left or 1/16" further back for whatever reason, it won't be noticeable. With a flush or reveal mounting it will stick out if anything is off.

On top of this I am also worried about where to position the sink depth wise from the wall. Do I go 4" from the front edge or 4-1/2" or more or less and does that leave enough room for the faucet after the 3cm thick backsplash is installed. I am sure the fabricator will advise but I am typically so detailed oriented I want to figure it all out instead of hoping it all works out at the end.

sum... the front to back location has to do with a couple of things.
the thickness of the backsplash
the front to back measurement of the sink
and the size and location of the faucet base, the escutchen

you have a double bowl sink so the faucet is going in the back.
you got a window behind the sink?
will the sill bump into the faucet?
believe it or not, sometimes the rim of the sink can overhang the faucet holes. they just drill tight thru the stainless but whats left interferes you put the big metal washer on the shank of the faucet and tighten it down and the faucet looks like the leaning tower of Piza. .

Sum it sounds like you are all set. I agree with you on the sink reveal, typically on an undermount sink the hole is smaller than the sink so you don't see the sink edge, and for the other reasons you mentioned. Just be clear with the fabricator what you want and they will cut it that way. Many times the structure of the cabinet will influence decisions on where the sink and faucets get placed from front to back.

This is why it's become standard practice for the countertop guys to want the sink onsite for the measuring. If they're not using the provided template, they will likely take the sink with them, which in my view is more than OK since it greatly improves probability of favorable outcome.

We had soapstone counters in the last house, and got the owner to give us a quick tour of the fabrication area. They had 2 CNC water jet machines that could accommodate something like a 10x20 ft slab. The laser measuring program uploads a file to the CNC and they just let it run. Extremely accurate!

packy I know exactly what you mean by the leaning tower of Piza. Basically the faucet hole needs to be drilled such that the tightening collar from the bottom (not the base or the shaft) should fully clear the SS sink's edge, or any clips.

Sometimes that is not even a round nut collar, sometimes it's a rectangular shaped horse shoe that goes up before that collar so you have to account for that horse shoe shaped thing too.

Don, well, the fabricator came today to remove the existing granite countertop and to make templates for the new.

Well it's just my luck the fabricator two men team, had trouble with English, so a bit of a communication problem there.

Once the old countertop removed, they took measurements and said no template needed they will do all modifications on site. The only hole they will cut at the shop is for the sink.

I thought the estimator told me they will cut the backsplash's three electrical outlet holes, and the
dip across the back of the over the range microwave at the shop and only drill the faucet on site, but now the fabricator said all those will be done on site and it "will be perfect, no worry".

The new countertop is a 3cm quartz slab. Initially I only wanted to do the countertop and use tiles for the backsplash which will add very little thickness to the wall, but the estimator talked me into using the same material for the backsplash because I will be buying a full slab and using only half of it, but that adds 3cm (1-1/4" to the back wall.

I worry about the placement of the sink front to back, but the fabricator said "no worry, everything is standard it will work". I offered for him to take the sink with him, he said no need. OK. I did give him a revised template, now this is my template not the sink manufacturer's template.

After he left, I test fitted the sink myself using two 1X boards to hold the sink up on the left and right sides.







I placed the sink very close to the front of the cabinet. Like 1" back from the front of the cabinet, I think the slab will be 2" proud of the cabinet, which will make the sink's edge 3" back from the counter, and the sink's bowl rim about 4" back. If I position it like this, there is NO ROOM whatsoever on the front to install any clips.



That will put the back edge of the sink 4.5" from the back wall, but since the backsplash will be 1-1/4" thick, the sink's edge will be only 3" or so from the new finished back wall. That is the space allowed for the faucet. I measured the faucet shaft/stem can go through a 1-1/4" hole, but that base collar from the underside may be 2+" and it needs to clear the sink's edge to avoid the faucet from being mounted crooked. It's tight, and it may result in no front clips at all.

Here is the Kohler faucet Tyne R21415-VS with the sink.



Yesterday, after deciding I do not want a 1/2" reveal for the sink mounting as suggested by the manufacturer, I made myself a new template, by cutting a cardboard 3/4" smaller then Elkay's provided template.

This is the Elkay sink.



My template (smaller) on top of Elkay's template (larger) on top of the sink.



This is my template over the sink. This is what the fabricator took with him.

Sum,

On our most recent remodel, the countertops overhung the sinks by a half-inch all around. There's a gap between the sink and the countertop that never gets cleaned, but it doesn't appear to need cleaning.

The sinks and countertops didn't come with clips. A thick bead of GE silicone was applied all around the sink rim, then the sink was laid on top of the upside-down countertop. It was clamped through the drain hole to a 2x4 under the counter and left alone for 24 hours.

Silicone alone does not hold up stainless steel sinks well to stone countertops. I have, a number of times, have had to reattach sinks that had dropped off the countertops because the silicone could not handle the weight of a sink filled with water.

I use these clips

george 7941 said:
>Silicone alone does not hold up stainless steel sinks well to stone countertops.
>I have, a number of times, have had to reattach sinks that had dropped off the
>countertops because the silicone could not handle the weight of a sink filled with water.

Here in northern California, all they ever use is GE Silicone, for ceramic or metal sinks. The countertop fabricators formerly supplied clips, but not anymore. Lay a THICK bead of silicone around the perimeter of the sink, assemble to the upside down countertop, clamp in place through the drain(s) to a 2x4 across the counter.

The countertop folks came today. They did the cut out for the sink using my version of the template and also preinstalled six threaded anchors for clips. They recessed the quartz below and epoxied in the anchors.













They then applied some adhesive sealant to the top side of the sink plus the clips.









When it came time to drill the faucet hole, I remember what Packy said and stopped the installer to let me check his position of the hole. He told me it's standard but I said nothing is standard just bear with me. I climbed under the sink cabinet and measured where the SS sink's lip ends, from there I figured where that is on the top side, then I measured the diameter of the round nut that goes on the shaft from below, added half of that to the sink's outer lip to position the center point, which will prevent that nut to be half on the sink's edge and half on the quartz. So here is the underside, the nut is right at the edge of the SS sink's edge. I am pretty happy with how the faucet hole is positioned.





Edited 2 times.

Sum you continue to blow me away with all of your photos, sharing your experiences and so much more. Thank you.

Sum, came out great! I've not seen anybody recommend using full 3cm thickness on the backsplash. Did it leave enough room for the faucet handle to rotate fully backwards for temp control or does it hit the backsplash? I know this is a plumbing forum, but this would have been a great opportunity to bring the electric up to code by adding an outlet to the right of the sink.