Undermount Sink Installation Guide

Installing an undermount sink can be a DIY project if you’ve got excellent skills and experience and the sink hole has already been cut.

For undermount sink installation, you’ll need:

  • The sink installation instructions (which should be completely read before starting)
  • Clamps or anchors included with the sink
  • Drill and bits
  • Driver or screwdriver
  • Silicone caulk

You may also need plywood, dimensional lumber and wood screws if the sink installation requires you to build heavy-duty support to accommodate the weight of the sink in order to relieve stress on the countertop.

kitchen sink installing

Installing an Undermount Sink

If you’re not familiar with the procedures outlined in these steps, hire a professional kitchen installer for the work.

  • Turn the countertop or substrate upside down
  • Clean the top of the sink sides with denatured alcohol
  • Run a ¼” bead of silicone caulk around the sink opening where the sink will contact the underside of the countertop or substrata
  • Position the sink, and press it firmly into place
  • Remove the excess caulk with a putty knife and towel or similar
  • Install the clamps that secure the sink to the underside of the countertop
  • Once the countertop has been installed, install any additional brackets or supports for the countertop that are required
  • Tip: For materials like concrete and natural stone, you’ll be required to pre-drill holes for clamp and bracket screws. Use a stop on the drill, so that you don’t drill through the countertop
  • Tip: If you’re installing a very heavy undermount kitchen sink, see the instructions in the Farmhouse Sink Installation Guide for installing supports that rest on the sink cabinet floor to provide the most support
  • Install the garbage disposal and sink drain
  • Install any included accessories such as dishwasher lines or a tankless water heater

The Cost to Install an Undermount Kitchen Sink

If you’re starting a total kitchen remodeling project, this cost will be included in the whole and might not be itemized. If you’re hiring someone just for the installation of the sink, expect this price range:

  • Undermount kitchen sink installation: $150-$500

Keep in mind that the sink installation is a two-part process, before and after the countertop is installed. This increases the cost.

A simple job that includes attaching the sink to the countertop and then later installing the drain line will cost $150-$225. The price will go up if the sink has two or three bowls and therefore additional drain lines or if extra accessories are included.

If you’re installing an on-demand/tankless water heater, a great choice when there is high consumption of hot water at the sink and dishwasher, your costs will be significantly higher due to the need for an electric line or a gas line.

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Undermount Kitchen Sink Installation FAQ

Here is a brief undermount sink installation Q&A that covers other important topics.

Should I save money by cutting the sink opening myself?

It isn’t recommended. Hiring a professional for this precision-required task makes more sense. However, if you do consider it, take into account the relative risk and reward. If you do the job correctly, you might save $75-$150. If the cut is wrong, the cost to replace the countertop section could top $1,000 depending on the material.

Does a composite sink require extra support?

Anytime an undermount sink is installed, adding support is recommended.

How much does it cost to install a garbage disposal?

Better units cost $100 and up. The installation will cost $75-$125 unless the installer has a minimum service fee that is more.

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