How to Replace a Countertop Sink With an Undermount

Replacing a countertop sink with an undermount sink makes kitchen cleanup easy.

Homeowners love the look and function of undermount kitchen sinks. Because they are mounted underneath the countertop, undermount sinks make cleaning the kitchen easy. Countertop sinks have a lip that catches water, food and other debris during kitchen cleanup. Replacing a countertop sink with an undermount sink can only be done on stone or solid surface countertops. Other types can be damaged by moisture running down the edges of the countertop.

Things You'll Need

• Adjustable wrench
• Utility knife
• Stone polisher
• Silicone caulk
• Measuring tape
• Undermount sink and clips
• 2-by-4 board
• Ratchet clamps
• Epoxy glue

Instructions

1. Determine if your countertop can support an undermount sink. Most professionals recommend that undermount sinks be installed in stone or solid surface countertops. If your existing countertop is not compatible with an undermount sink it is best to leave the countertop sink in place, or to replace it with a new countertop model.

2. Turn off the water to the sink. Disconnect the water lines by loosening the nuts with an adjustable wrench. Use a wrench to disconnect and remove the drain and P-trap from the sink.

3. Check to see if there are metal clips on the underside of the countertop. If there are clips you will need to remove them.

4. Lift the countertop sink out of the countertop. Discard the sink. Clean away the caulk or plumber's putty from the sink hole.

5. Prepare the sink hole for the undermount sink. Polish the edges of the stone countertop around the sinkhole with a power buffer, or hire a professional to prepare the hole for the new sink.

6. Measure the sink hole opening in the countertop with a measuring tape. Refer to the dimensions in buying the correct size of undermount sink. Consult the sink manufacturer's directions to determine the placement and number of clips that are needed to hold the sink up.

7. Apply a bead of silicone caulk along the rim of the undermount sink. Set the sink in place under the countertop. Place a 2-by-4 board on the countertop over the sink hole. Place a ratchet clamp or bar clamp on the board and connect it to the undermount sink through the drain hole of the sink. For a two-drain sink, use two clamps. Position the sink and tighten the clamps carefully to hold the sink in place.

8. Make sure the bottom surface of the countertop near the sink hole is clean. Apply epoxy glue to the clips that are included with the undermount sink. Set the clips in place on the bottom of the countertop to hold the sink in place. After the epoxy has set, attach any other required hardware for holding the sink in place. Let the epoxy and caulk dry for 24 hours before removing the clamps.

9. Reinstall the plumbing for the sink. Connect the P-trap and drain with a wrench. Install a new faucet per manufacturer directions.

References

• Home Construction Improvement: How to Install Undermount Sinks
• Ask the Builder: Undermount Kitchen Sinks
• Ron Hazelton's Housecalls: How to Remove and Replace a Porcelain Kitchen Sink