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