Undermount granite composite sinks are classical and distinctive, and they are made for our comfort. People who are using it for the first time do not know much about installing an undermount granite composite sink.

In this article, we will let you know about the step-by-step procedure of installing an undermount granite composite sink. Installing the undermount granite can be a difficult task for all those who have bought it for the first time and who have tried to installing it without knowing the correct procedure.

To know about the correct procedure, you should follow all the steps carefully that we have explained below in this article.

How to Install Undermount Granite Composite Sink

Step 1: Collect all the necessary tool

Before installing a granite composite sink, you will have to make sure that you gather all the necessary equipment that would help you in installing the sink.

For this purpose, you will need a power drill, screwdriver, clamps, mounting hardware, and a silicone sealant.

Without these tools, it will become difficult for you to install the sink. If you do not have any of the tools I mentioned in the previous line, you must grab them first.

Step 2: Find a perfect sized exiting hole

Granite is a very expensive material therefore, before buying it, you need to make sure that the size of the existing hole for your sink is perfect to secure an undermount the granite composite kitchen sink. If the wrong size is brought, you cannot cut it yourself to fit the exact size.

Unfortunately, many people bring the wrong-sized granite, and when they cannot install it, they try to cut them on their own and end up messing up with the expensive granite. Therefore, it is important to find the perfect size of the existing hole so that you do not have to cut it down.

Step 3: Measure and mark the layout of undermount clamps

The next thing that you should do for the installation is to measure and mark the layout of the undermount clamps. For this you should use a 2×4 dimension lumber as it will help you in installation.

To start this process, first of all, cut the length into 1 foot which should be longer than the hole in your countertop. Then, lay this cut length in the center of the sinkhole horizontally. Under the side of the countertop, clamp the sink with the help of a bar clamp.

While fitting them, avoid the tightening of clamps in the sinks as they can damage the granite. Instead of the clamps, you can also use a snug fit that will fit your sink into a proper position.

Now along with the top of the countertop, shift the 2×4 length a little longer and make sure that the granite does not get damaged during this process. Again, avoid over-tightening of the clamps as it can damage the granite.

Step 4: Drill the spots for installation

Take a close look at the placement of the sink and attach wing nuts onto the screw heads. With the help of a pencil, mark the spots of the mounting clips to get the drill spots.

These spots are at the wing nut location, and it is the place where you will drill holes. After marking the spots, remove the sink and drill the holes marked with the pencils at each point. To insert the tap in the holes, drill a little bit ¼ inch.

Do not be harsh while drilling the holes, rather be gentle so that the granite does not damage. Now find the spots where you will drill the holes to attach undermount granite composite sink. After marking the spots, remove the sink and drill those spots gently.

Step 5: Clean the ridge

With the help of the rubbering alcohol, clean the ridge carefully. After cleaning the ridge, use the silicone sealant around the edges. Now re-clamp the sink in the perfect spot that fits it in.

Step 6: Tighten the screws

Thread the wing nuts and tighten the screws for your granite undermount sink. Then, let the silicone sealant dry for almost twelve hours and check the leaks near the rim of your new sink. You should also consider calling a professional plumber for the plumbing fixtures.

Frequently Asked Questions:

What holds an undermount sink in place?

Undermount sinks come with clips and undermount sink brackets that help the sink to fit in its place. Moreover, the silicone sealant that you use at the side after cleaning the ridge also helps hold the undermount sink in place.

What kind of caulk to use for undermount sink to granite?

Silicone caulk is best to use for undermount sink to granite. It is the best caulk for the fixture of the kitchen, like sinks. Before applying the silicone caulk, cover the surrounding granite with the help of the painter’s tape. The new layer of caulk should be joint at the joint.

Can an undermount sink be installed where an overmount exists in granite?

An undermount sink is a sink that is mounted under the countertop in the kitchen or room, while the overmount sinks are mounted at the top of the counters. Suppose you already have a overmount installed on your cabinets, then yes. In that case, you can install an undermount sink over there in granite. The only thing you will have to take care of is the size of the sink-mounting hole in your countertop.

Which is better in granite, over, or undermount sink?

An overmount sink is not like an undermount sink. It is cheaper than the undermount sink, and installing an overmount sink is also not very difficult. You can install it any time on your countertop with simple techniques. On the other hand, the undermount sink doesn’t have installation holes. So, it is difficult to install the undermount sinks as well. Moreover, they are expensive than overmount sinks. So, in granite, overmount sinks are better than undermount sinks.


To sum up, the step-by-step guide of granite undermount sink installation has been briefly discussed above in this article.

So, if you want to install your undermount granite composite sink. In that case, you will have to follow the steps mentioned above carefully. Hopefully, these steps will help you a lot in the installation of your granite sink.

It is not a very difficult job if you are properly aware of what you are doing. If you have any confusion and questions regarding installation of undermount granite sink, we hope that this article solved your queries.

If you still cannot figure out the procedure, will be best for you to call a professional to proceed with installing an undermount granite composite sink.

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