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How to Install an Undermount Kitchen Sink: Easy Installation Guide

How to Install an Undermount Kitchen Sink
Written by Callum Strempel
Last Update: November 30, 2022

Away from how smooth they may appear; they tend to make cleaning counter-top easier.

This is because sinks are adhered to the counter, and has no noticeable connections on the bowl that can be greased when cleaning the surface.

It is important to know that a poor undermount sink installation can affect counter-top in modern kitchen settings.

But how to install an undermount kitchen sink the proper way?

It is advisable with a well-finished cut countertop that is constructed within the actual size before mounting the sink.

Ensure that all the required holes that will ensure the successful completion of the process is predrilled and ready for accessory and facet mounts.

It is recommended that you have all your holes drilled by pros.

This is because the entire process can be messy and oftentimes, it necessitates the use of technical tools that might not be common if you intend to “Do It Yourself.”

And doing the entire process yourself could be very expensive, especially if you mistakenly crack or chip the top while carrying out the process.

You will need to provide the countertop fabricator with adequate information on the faucet and sink you intend to install to get them to create an opening that will perfectly fit the sink’s shape and size.

So in a short while, we will be looking at how to install an undermount kitchen sink.

We will evaluate some of the clean arrangements that can be done to carry this out effectively.

How to Install an Undermount Kitchen Sink

Undermount Sink Installation Instructions

Reveal is a term that explains how visible the sink appears to be while viewing directly to the sink.

Basically, the three reveal styles are:

1. Positive reveal – the positive reveal exposes some part of the sink rim.

2. Zero reveal – the sink walls are flush with the countertop opening

3. Negative reveal – countertop extends past sink walls.

Your visual preference should be your guiding principle when selecting a suitable revel style.

Although, often time, most fabricators prefer to use zero-reveal style as they believe it appears more appealing and clean.

Views from most professionals have also revealed that positive reveal creates a sink with a narrow surface that is difficult to clean.

The truth is this; surfaces certainly become untidy in as much as we sponge mess on the countertop into the under-mount sink.

On the other hand, negative reveal produces surfaces that are difficult to clean and can be a home to most pests.

  • Putting Up Your Workspace

Before you install an undermount sink on a cabinet base, it’s best to attach it to a countertop.

A sink base has limited space and will appear awkward if you do otherwise but if for personal reasons you consider installing a sink with its top in place or want to reset the current under mount sink which is detected from underneath the counter.

To do this effectively, you will need to cut out the side of the cabinet; this will provide easy access to pin fittings; which will help protect the sink from the other side of the counter.

You should get a work stand ready to provide you with the maximum support before the arrival of your countertop; this will allow you to work both below and above without cracking or flexing it.

Although the weight and the length of the top can be a great deal, an easy way to get around this –is to set a few bys across sawhorses. Using a tabletop with no frame can also serve as a better option.

Before starting, arrange the tools, that you will need while installing the sink, these include:

  • Two-part epoxy
  • Masking tape
  • Sink
  • Faucet and accessories
  • One tube of 100% silicone adhesive caulk
  • Denatured alcohol
  • Bar clamps (depending on attachment method)
  • Sink-mounting clips with glue-on stud bases
  • Right-Side down or Right-Side Up? Is This a Tricky Question?

Although, there are professional sink installers who prefer to have their job done underneath the counter while facing upward on a table that provides maximum support.

While others will prefer a finished surface, that is positioned upward.

This wholly depends on individual preference; as each style has its pros and cons.

  • Bottoms-Up Installation

It is pretty easier and faster to get a sink installed using its underside, though the technique may appear a little weird if you want to know if each sink is rightly positioned on the spaces you created to get an anticipated reveal treatment.

If you want to get a head start, you will need to slab the underside and the work stand to face upward. Use the following steps:

1. Ensure you clean the inner walls in the cutout with other areas that surround it using a rag that is damped in alcohol. And ensure all surfaces are free from dust and stains.

2. Use tape to seal up the cutout edges.

3. Position the sink over the cutout, ensure it is centered to attain the desired reveal, then trace out the rim and create an outline where you will add the silicone glue. When this is rightly done, position the sink aside.

4. Layout the sink clips’ position, and outside each of the lines, you drew and create each clip on both corners of the sink, and create a space that doesn’t exceed 10 inches from both sides.

5. Ensure you mix epoxy to glue the sink-clip studs. Spread out epoxy at the bottom of each individual stud, after which – you apply enough pressure on it and then squeeze out the epoxy to get into the holes you created for the stud bases.

Afterward, allow getting dried for a minimum of 24 hours.

6. Add bead generously on the silicone at the edge of the cutout once you observed that the epoxied on the sink is clipped enough.

7. Center the sink and ensure it is rightly set in place over the opening.

Check the outcome by looking under the work stand to ensure the sink edge is rightly aligned, and both sides of the reveals have equal sides.

While doing this, you can carry out a couple of adjustments if need be.

8. Once you attain maximum satisfaction, then it is time to slip up the inserted sink clip that is on the studs to make one end carry the sink rim.

Thread out each wing-nuts on the studs and fasten each down till it gets to the bracket.

Ensure that each nut you fastened is finger-tight; this will eliminate unnecessary strain at the top of the counter.

9. Clean up the cutout edge to reduce the amount of silicon that is squeezed out from the edge.

After this is rightly done, you can remove all the tapes and clean out the silicon that penetrates the tape.

Use alcohol to ensure maximum results.

10. Install the faucet if possible.

11. Connect the faucet tube to a water source after you have installed the counter.

  • A View from the Top??

Most installers will prefer to install the sink using the countertop right side up.

They believe doing so can provide a perfect view of the reveals at the last stage of the sink clips to be well fastened to hold the sink that is in the underside.

This is also a step you are also required to take whenever you intend re-install under mount sink that already exists or falling from the countertop.

The best way to install an undermount sink from an above position is to ensure you hang it underneath the cutout by using a bar clamp.

If you intend to reposition a sink that was previously installed then it best you first detach it entirely from the countertop after then you can prop it up underneath the cutout.

  • Setup props stacked 2 x 4 in. Boards or some temporary stand to support the sink in an inch or 2 underneath the cutout.
  • If you intend to reposition, take off all the water supply that is directed to the sink, afterward detect the faucet and P-trap and disposal, and take the strainer body away from the sink-drain hole.
  • Take away all the sink-clip brackets that will restrict the sink from falling off. Position the sink on a prop.
  • Use solvent, knife, and scraper to wipe away dried glue from the bottom of the counter and the sink rim.

Once you have a clean surface at the bottom of the counter then it’s time to ensure you clean and install the new sink clip studs, at the right position, you think you feel it’s needed.

To Suspend the Sink Beneath the Cutout

  • Get two scraps of 2 by 6 inches. Boards that are approximately 2 ft. Ensure it extends more than the sink.
  • Take away the handles from one or more bar clamps if you have a double sink you are working on, then it’s best to go for double.
  • Thread up the bars from underneath the sink.
  • Set one 2 by 6 inches. The board is located the below the sink and the stationary jaws clamp. Place about 2 by 6 inches of board scrap at the top of the counter, while spinning across the sink.
  • Regulate the clamps to hang the sink, and let it be an inch beneath the cutout, while you arrange the rim off with each cutout edge.

To Finish the Undermount Sinks Installation

  • Add silicon glue underneath the counter-top around the cutout.
  • Fasten the clamp to get the sink rim to get in close contact with the glue and counter-top bottom, regulating the position of the sink to get the desired reveal.
  • Avoid over-tightening the wing-nut as this could lead to cracks on the counter-top.
  • Wipe off all the silicon squeezed out during the process.
  • Restore the faucet and drain connection if need be.

You can do this either way; right side up installation or upside-down.

Remember, a proper installation process will help you get rid of kitchen sink smell easily in the future.

In summary, the entire process of installing an undermount kitchen sink is simple and easy and can be effectively carried out with little or no technical skills.

Although, there are instances when you might be limited in terms of accessing the right tools for the job.

Nevertheless, if you feel uncertain regarding any step, then it’s best to consider the help of a professional.

About the author

Callum Strempel

Licensed Plumber

Hi, I’m Callum, a full time plumber with a plumbing license issued by my state. So far, I’ve spent nearly a decade and a half installing and fixing a wide variety of plumbing components and units. My profession inspires me to talk about the kitchen and bathroom (and the plumbing system) so confidently and knowledgeably that I offer my free consultations to help neighbors and fellow homeowners every now and then. As I enjoy installing faucets, sinks, showers, and fixtures, I love to see people enjoying services from those components for years to come. So, I write every week to inform you and others. Will you mind going through some of my articles on this website?

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