How to Fasten an Undermount Sink in a Solid Surface

An undermount sink provides a seamless look.

Remodeling your kitchen usually involves installing new countertops and a new sink. Many homeowners opt for the clean look of an undermount sink instead of the standard drop-in style of sink. Undermount sinks require a little more work when it comes time to install the sink in the countertop. A helper is necessary to assist in holding the sink while you secure it to the countertop. Fastening an undermount sink to a solid surface requires using sink clips, which resemble short strips of metal with a hole in the center of each. Sink clips are available at home improvement centers.

Things You'll Need

• Helper
• Sink clips
• Drill with bits
• Phillips-head screwdriver
• Rag
• Silicone caulk
• Utility knife
• Caulk gun

Instructions

1. Go under the counter and push the sink up to the sink hole in the counter. Ask a friend to grab the sink through the open drain holes and hold the sink in place.

2. Locate and mark the mounting holes necessary for the sink clips. New sinks have a template to assist gauging the proper distance. Take one of the semi-flat sink clips and hold it over the sink lip and counter. Mark the hole in the center of the sink clip onto the counter with a pencil. Mark the mounting holes for all the clips around the perimeter of the sink.

3. Lower the sink and move it out of the way. Drill holes for the sink clip mounting screws where you made the marks, using the appropriate bit for the particular countertop material. Drill only half the distance of the screw length if you're mounting the sink to wood. Drill the full length of the screw if the sink is being mounted to granite or marble.

4. Clean the mounting area under the sink with a rag to remove any residue.

5. Load a tube of silicone caulk into your caulk gun. Cut off the tip of the tube at an angle with a utility knife. Squeeze the trigger to start the caulk flowing from the tip. Apply a 1/8-inch bead of caulk on the top edge of the sink.

6. Screw the sink clips loosely into the bottom of the countertop. Position the sink clips so they do not interfere when you raise the sink up to the bottom of the countertop.

7. Position the sink under the countertop. Ask your friend to hold the sink from the top, again using the sink drain holes as handles. Reposition the sink clips so that half of the clip is over the sink lip and the other half is under the countertop. Tighten all the retaining screws to secure the sink to the countertop.

Tips & Warnings

• Allow 24 hours for the caulk to cure before using the sink.

• If you don't have a helper available, you can cut boards longer than the sink hole width and then clamp or tie the sink to the countertop.

References

• Elkay: Undermount Sinks Installation Instructions
• South Metro Denver Chamber of Commerce: How to Install Undermount Sinks