Reattach an Undermount Kitchen Sink

In this video, Ask This Old House plumbing and heating expert Richard Trethewey offers undermount sink support by helping a homeowner reattach an under-the-counter kitchen sink to a granite countertop.

How to Reattach an Undermount Kitchen Sink

1. Turn off the water supply to the sink.
2. Disconnect plumbing connections using a wrench and unscrew by hand.
3. Disconnect any remaining sink clips using a screwdriver.
4. Remove sink from granite and set aside.
5. Scrape off leftover caulking on the sink and the underside of the granite countertop using a putty knife.
6. Insert undercounter-mount sink clips into the existing holes in the granite.
7. Loosely screw the machine screws into the brass threaded insets using a screwdriver.
8. Put a bead of silicone caulking around the rim of the sink using the caulking gun.
9. Place the sink back into the hole in the granite and pull it up into place using a string wrapped through the drain.
10. Have another person underneath the countertop to tighten the machine screws into the granite and place the clips under the rim of the sink.
11. Place wood braces tight under the sink for support.
12. Run a finger along the rim of the sink to smooth out caulking and add more as needed.
13. Reconnect pipes and turn the water back on.
14. Wait 24 hours before removing the wood braces or using the sink.

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