How to Install a Farmhouse Undermount Sink

As an Amazon Associate WiseGuidePro Earn From Qualifying Purchases.

Farmhouse undermount sinks are sinks installed under the counter and are held in place by caulk and heavy-duty clips. There’s no rim between the sink and the countertop because of the installation method.

These sinks do not have crevices to hide dirt, are easy to clean and enhance the style of any kitchen. A good undermount sink makes a sleek component of any kitchen.

The fact these sinks attach to the underside of a countertop makes them a little challenging to install. In this guide, we’ll take you through steps to help you install one without professional help.

Step by Step Complete Guide to Install a Farmhouse Undermount Sink

How to Install a Farmhouse Undermount Sink

Step 1: Estimate the size of the undermount sink

If working with a pre-cut countertop, figure out what sink size you need. To do so, measure the length and width of the hole and write it down. These measurements should help you get the best undermount sink to fit the space.

If you have an old sink, the process is much easier; you just need to measure it and get a new one of the same size.

Step 2: Figure out where to install the sink

If working with a new countertop, choose a spot for it. The location will depend on the location of water supply lines in your home. Although most sinks sit in the middle of a countertop, you can choose a different aesthetic of your liking.

One thing to note is that concrete and stone countertops work great with undermount sinks. Other types tend to crack during the process.

Step 3: Select a reveal style

The reveal style you decide to use will determine how much of the farmhouse undermount sink’s rim stays visible after installation. The process is very important for appearance and ease of cleaning.

There are 3 types of reveals including;

  • Zero reveal – The countertop’s edges are flush with the sink. Sinks with this reveal don’t leave extra space for germs or food particles to slip into.
  • Positive reveal – Half of the sink’s rim stays visible. The rim will, however, get dirty, similar to drop-in sinks.
  • Negative reveal – This hides the sink’s rim under the countertop. Overhanging countertop edges get dirty and are difficult to clean.

Step 4: Trace the sink’s outline on the countertop

If your sink doesn’t come with a template, you can use it to trace the outline on the countertop. Flip it over and trace the outline with a pencil.

After that, remove the sink and then measure the width of the rim. On average, it should be 3/8cm wide. Make another outline 3/8 cm inward from the original lines.

To avoid cutting the original outline by mistake, erase it.

If your sink comes with a template, you’re a lucky chap. Just put the template over the countertop and use it to trace the outline.

You also need to remember that the outline has to be smaller than the sink’s opening. This is because the rim will rest against the countertop after installing the sink.

Step 5: Cut the Countertop

Put on your safety gear and get the right saw for the materials you want to cut. If cutting stone, get a circular saw. The saw should have a diamond-coated blade.

If the material is laminate, get a jigsaw that comes with a special laminate cutting blade.

If working with stone or concrete, it’s advisable that you hire a countertop fabricator to make the cuts. These countertops are expensive, and you don’t want to damage them in the process.

To make holes for faucets and other accessories, use a drill. Ensure that you use a drill that is suitable for the countertop.

Step 6: Stack wood boards under the countertop to hold the sink

To support the farmhouse undermount sink’s weight, you need to construct a support frame. To do so, stack wood boards of 2 x 4 inches until your sink is right beneath the countertop.

If you don’t have wood, you can use other sturdy objects or get a friend to hold the sink in place so that you can attach it to the countertop.

After that, center the sink in the middle of the hole you made on the countertop. Next, adjust the sink as needed and align the rim with the cut edges of the countertop if going for a zero reveal look. Look down to ensure that the sink rests where you want it.

If going for other reveal styles, take your time to position the sink. Then, measure the distance between the rim and the countertop’s edge and ensure that it’s even on all sides.

Step 7: Clamp the sink to supports

Get an adjustable bar clamp and a couple of pieces of wood (2 x 6 inches). Set one piece of wood under the sink and another over the hole in the countertop. Clamp the wood boards so that your sink stays suspended about 2.5 cm below the countertop.

If working alone, use an undermount sink harness. It clips to the sides of the countertop. To lift the sink, all you’ll have to do is tighten it up.

Step 8: Glue the studs to the counter’s underside

Get some undermount sink clips, epoxy paste and a hardener. Mix equal amounts of the paste and hardener using a wooden stirring stick.

Next, hold the studs to the countertop and spread the mixture over them with the stirring stick. Position all the studs around the sink’s rim and corners.

For the best results, glue a stud near every corner of the sink and spread the others out. Keep no more than 10 studs 25 cm apart.

Step 9: Apply silicone caulk

Set caulk in a caulk gun and spread a thick bead around the cutout in your countertop. Ensure that the caulk bead remains above the sink’s rim.

This adhesive will hold your farmhouse undermount sink in place for the longest time possible.

Step 10: Tighten the Clamps

Tightening the clamps will raise your sink so that it presses against the caulk bead. Check the sink’s positioning and adjust it before the caulk solidifies.

If satisfied with the placement, leave it in place for the caulk to solidify.

Step 11: Install the Sink Clips and wingnuts

Fit a clip over the already installed studs and tighten it in place with a wingnut. Position the clips in such a way that the slotted end gets over the stud and the solid end underneath the sink’s rim.

Twist the wingnuts clockwise and tighten them. With the sink clips in place, they’ll secure your sink tightly to the countertop.

Ensure that there are no gaps between the farmhouse undermount sink and the countertop. Should you notice a gap, it means that the clips are not tight enough.

Also, ways tighten the wingnuts by hand. Avoid overtightening them, as this can damage the countertop.

Step 12: Clean the excess caulk with denatured alcohol

When pushing the sink against the countertop, some caulk may squeeze out. You need to wipe it out before it hardens. Once it cures, it gets extremely difficult to remove.

To do so, get a rag and dampen it with denatured alcohol and use it to wipe away the caulk.

Step 13: Mount the faucet and other accessories

At this stage, you’re almost done. Set all accessories on top of the caulk and install them over the holes in the countertop. After that, install the water lines.

Run these water lines through the faucet and control knobs to complete the installation process.

Conclusion

Although undermount sinks are a little tricky to install, following all the steps listed above will help you do it yourself. We hope that you’ve found the guide helpful.