How to Install a Kitchen Sink

Instructions on Installing an Overmount Kitchen Sink

By Mark J. Donovan

Installing an overmount kitchen sink is something most do it yourself homeowners can tackle if they have a few basic tools and the desire.

Tools required include:

  • Jig Saw
  • Pencil
  • Drill with 3/8” drill bit
  • Crescent Wrench
  • Bucket
  • Putty Knife
  • Channel Lock Pliers
  • Tape
  • Silicone Caulk
  • Plumbers Putty

Buying Kitchen Sink

The first thing that you need to do is purchase the right size overmount kitchen sink for your kitchen countertop.

Make sure when measuring the depth of your kitchen cabinet and countertop you account for any backsplash. A backsplash will reduce the maximum allowable depth of your kitchen sink by approximately 1-2 inches.

The width of your kitchen sink is dependent on the width of the kitchen cabinet you plan on installing it in. Check the inside of the kitchen cabinet to account for any drawers or other obstacles that could limit the size of the kitchen sink.

If you are replacing a kitchen sink the task of selecting a new one is a little easier. You have a pre-defined hole that already specifies the size of the kitchen sink you can install. You may be able to, however, install a larger one if there are no obstructions underneath the cabinet and you are willing to cut a larger opening.

Note: If there are separate holes for the kitchen faucet handles and spout you will need to account for them in your selection of a new kitchen sink.

Kitchen sink considerations

Remove old Kitchen Sink

If you are replacing an old kitchen sink, first turn off the water supply valves underneath the kitchen sink.

Next, disconnect the supply and drain lines from the kitchen faucet. Note that a bucket comes in handy at this stage to catch the small amount of water that is located in the J-trap.

Remove any sink hold-down fastener clips that maybe holding the kitchen sink to the countertop.

Using a putty knife, slide the edge of it around the perimeter of the kitchen sink to loosen any caulk that maybe forming a seal around the kitchen sink.

Now simply pull the kitchen sink out of the kitchen countertop.

Cutting an opening for a new Kitchen Sink

If you are installing a new kitchen sink, you will need to use the template which should have come with the kitchen sink to trace out the rough opening for it.

Center the template on the kitchen countertop in the location of where you want the kitchen sink to reside. The template should be positioned at least 1.5” back from the front edge of the countertop, however not so far back that it looks un-centered. Normally the kitchen sink should sit no more than 3-4 inches back from the edge of the kitchen countertop.

Once you have located the position of the template secure it with tape.

Using a pencil, trace around the template.

Kitchen Remodeling Bid Sheet

Note: If a template did not come with the kitchen sink, simply turn the kitchen sink upside down and position it properly over the kitchen countertop and trace around it. Then remove the kitchen sink and draw another outline that is approximately ½” in from the first outline you drew. You will cut on this second inner line. This inner line will enable the kitchen sink flange to rest on the kitchen countertop.

Remove the template, and drill 3/8 inch pilot holes in each of the corners of the template area. Make sure the holes are within the boundary of the template outline.

Using your jig saw, insert it into a pilot hole and begin cutting on the inside edge of your outline. Have someone underneath the kitchen countertop holding the cutout piece in place until you have completely cut around the outline. This will prevent the cutout piece from breaking off and possibly damaging the surface of the countertop. Warning: make sure the person underneath the countertop is wearing eye protection and that his or her hands are away from the saw blade at all times.

You may also need to drill holes for your faucet supply lines and spout depending on what type of kitchen sink you are installing.

Installing Kitchen Sink

To minimize your work underneath the kitchen countertop it is best to attach the kitchen faucet to the kitchen sink before you install the kitchen sink.

Turn the kitchen sink upside down and attach the faucet to the kitchen sink using a crescent wrench. Make sure to first apply a bead of caulk or plumbers putty to the faucet base before attaching it to the kitchen sink.

Now attach the flexible supply lines to the faucet assembly. Again, use your crescent wrench to tighten the supply lines to the kitchen faucet.

Clean around the cut out area removing any sawdust or loose debris.

Apply a bead of silicone caulk around the perimeter underside flange area of the kitchen sink.

Turn the kitchen sink/faucet assembly over and position it into the cutout area. Make sure the supply lines are properly fed into the supply line holes if required.

Press the kitchen sink firmly into place and immediately remove any excess silicone caulk.

Underneath the kitchen sink, fasten the kitchen sink to the kitchen countertop with hold-down fastener clips, if fastener clips came with the kitchen sink.

Install Kitchen Sink Drain Assembly and Supply Lines

With the kitchen sink installed, run a bead of plumbers putty around the bottom of the sink drain area and install the sink drain and drainpipe assembly. There is a lock nut washer assembly that holds the sink drain to the kitchen sink. Use a pair of channel lock pliers to tighten the lock nut washer.

Connect the J-Trap assembly to the sink drainpipe using your hands and/or channel lock pliers.

Connect the flexible kitchen supply lines to the house water supply lines using your crescent wrench.

Turn the water supply lines back on and test to see if the kitchen faucet operates correctly and that there are no leaks around the sink drain assembly or supply lines. If there are, turn off the supply lines and gently tighten the offending connection.

After testing the kitchen sink and faucet, let the kitchen sink set up overnight before using regularly.

For help on your kitchen remodeling project, see my Kitchen Remodeling Bid Sheet. The Kitchen Remodeling Bid Sheet provides a request for quote checklist section that you can provide to prospective kitchen remodeling contractors. It also includes a comprehensive kitchen remodeling cost breakdown table, in Microsoft Excel format, that allows the contractor to include his projected remodeling costs for every phase of the project.

Related Information

Additional Kitchen Remodeling Design Resources


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