How to Install Undermount Kitchen Sink

Undoubtedly, improper installation of your undermount kitchen sinks cannot be underrated. Surely, a poorly installed system can even affect the best quality countertop in your kitchen. With that, we shall learn how you install a undermount kitchen sink in this article. Prominently, Kitchen sinks are quite heavy to install straight to the concrete. Therefore, a clear arrangement has to be made.

The installation scheme

It is essential to install an undermount kitchen sink prior to setting down the countertop slabs. Usually, after establishing the countertop slabs, you will not be in a position to fix the sink. Consequently, you will not suitably seal between the underside of the countertop and the sink.

Install the sink supports

Basically, there are three methods you can use to install sink supports.

The 3 kinds of sink support for your kitchen

If you have a concrete countertop, ensure that the concrete does not bear the pressure of the sink. Rather, establish support using the plywood and the cabinet frame. Conveniently, these two will help to withstand the weight of your kitchen sink.

The commercial Bracket

The first sort of support is the commercial sink bracket marketed by the various granite supply firms. Typically, the commercial Bracket is made to be fixed onto the kitchen's cabinet frame. Carefully, follow the manufacturer's directions to ensure everything is perfect.

The custom Wood Frame

The second sort of support is a created wood frame that attaches to the walls of the kitchen cabinet. In this case, the frame supports or holds the sink by its flanges. Conveniently, leave some wiggle area between the cradle and the sink bowl. This is for the sake of aligning the sink with your countertop opening.

The custom Plywood Shelf

Another kind of support is a layer of the 0.75 inches plywood shelf. Suitably, trim this to fit in the cabinet. Normally, the plywood has an opening cut into it that your undermount sink falls into. Actually, the opening in the plywood needs to be large enough to permit the sink to be moved. The sink must align with the opening in the countertop. Seldom, it is helpful to rout a rout around over along the inner edge of the slot.

Additionally, it is necessary to cut openings for all the faucet and plumbing attachments that attach to the countertop. Always, the opening in the plywood needs to be large. Preferably, it should be large enough to permit tools to access the plumbing and faucet hardware.

Fix the sink onto the support frame of your cabinet

Always, be careful while fixing the sink onto the support frame of the cabinet. Actually, there have been some cases that people end up injuring themselves as they do this.  

Apply a reasonable bead of caulk about the top of the flange of the sink.

Here, you should employ a siliconized or silicone acrylic bath and kitchen caulk

Install the adjoining countertop slabs above the sink.

Properly sandwich it between the cabinet frame and the countertop.

What is the importance of caulking as a process of how to install undermount kitchen sink?

Most importantly, create a watertight fastener between the sink and the base of the countertop. Even as you apply the silicone caulk right along the flange, ensure that you do it with care. Always, it should be adequate to form a watertight seal. However, it should not be too much that it becomes untidy.

Remember, bare concrete will always react with silicone to give a dirty-looking, oatmeal-like density. Consequently, this will flow out of the sink connection points. Accordingly, you should seal the base of your sink openings. This is important so that the sealed concrete only touches the silicone.

How much time is required to install an undermount kitchen Sink?

Usually, an expert installer can fix an undermount kitchen sink just in 30 minutes or less. Indeed, as a homeowner, you need to gather all the necessary tools and equipment before calling a plumber. This way, the installation process will take short time as much as possible. If possible, you can do some basic things by yourself as you wait for your plumber. These may include dusting the base of the stone top and assembling the necessary tools and equipment.

How do you attach the undermount sink?

You do so by the use of a two-part epoxy adhesive and seal it with a silicone caulk around the perimeter. If you do not do so, the sink will pull apart from the underside and hence crashing the floor.

Most of the professionals can do the installation in less than one hour. These are the persons who have a long-standing experience on fixing these kinds of sinks.

The cabinet pull should always be ready in advance before you install the undermount sink. Make sure that you have the standard size of the cabinet that will accommodate and hold the sink.

Which one comes first? The undermount sink or the countertop?

Most people do have challenges in deciding which one to install first. It is important to note that doing the installation has a definite procedure. One has to come before the other.

In this case, it is advisable to install the undermount sink first before the countertop. The countertop usually has slabs that hold it firm. The sink has to go in first, because once you place the slabs, you will not be able to install the sink through the sink hole.

Apart from that, you will also not be able to seal the properly between the sink and the underside (below) the countertop. If you do it the other way round, you might have no other choice but to dismantle the whole thing and begin the process afresh.

Can these types of sink fall off to the ground?

You must be wondering on how this can happen, but of course it does. If you do not install it properly in the initial stages, then it will fall off. If you use silicone caulk instead of clips and straps, then the sink will not be stable.

The best way to avoid such incidences is by mounting it properly and making sure that it bonds well with the countertop.

Some of the impacts of a falling sink are the damages to the floor, accidents and injuries. Follow all the installation procedures to avoid such incidences.

Does undermount sink get molds? How do you take care of it?

One of the biggest challenges to this sink is the mold. It happens when the water gets in between the sink and the countertop.

Countertop material is not water-resistant and it is the component that will feel the major impact. Mold and mildew can also grow and hide beneath it.

To avoid these problems, you should try to cover all the available spaces between the sink and the countertop when doing the installation.

If the water does not get a space to pass through, the effect of mold will have a minimal impact. You cannot, however, avoid it completely because water will still seep through the caulk and the cement

Is vinegar and bleach well for dealing with mold?

When you install your undermount sink, you would always love to have it serve you for long. Both the bleach and vinegar can kill the mold.

However, vinegar is more effective and stronger than bleach. It works well in killing and removing mold in the porous material such as between the countertop and the undermount sink.


Assuredly, installing an undermount kitchen sink is not a big deal. Though there might be different materials for sink installation, the procedure should be somewhat the same. Expectedly, this article on installing undermount kitchen sink will sharpen your skills on this. Nevertheless, if you still feel hesitant to do it on your own, you can seek plumber's service.

2 thoughts on “How to Install Undermount Kitchen Sink”

  1. Everything is very open with a really clear clarification of the issues. It was definitely informative. Your website is useful. Thanks for sharing!


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