Undermount sink installation, SHIMS?

4 years ago

Hi everyone,

My husband and I are redoing our kitchen. A lot has been DIY, but we paid to have the countertops and sink installed. We went with a Kraus undermount workstation sink (KWU110-32). I wasn’t present for the installation, but they didn’t use the clips that came with the sink or look at the instructions for installation…. I wasn’t worry because they do this for a living!

After the sink was installed we waited 48 hours to connect the sink. I had been living with out a sink for several days, so there were at least three loads of dishes to be washed. After the second load, I saw the silicon pulling away and the sink could be moved up and down from the bottom. After crawling under the sink, I saw there were only four big clips that were too big to hold the sink into place. I wasn’t sure if they had not been tightened appropriately or if the clips were just to big. I called the countertop company back and they made an appointment to come back and reinstall the sink.

Again, I couldn’t be present for the re-installation because the installers came an hour and a half before the beginning of the 5 hour window they provided (this is when I started to get annoyed). When I came back to see the installation, the same clips were used and no additional clips were added, but wooden shims were used to fill the gap between the sink and the clips. The second installers did not speak a lot of English and my husband speaks a little Spanish. The impression he got from the second installers the wrong clips were used initially.

I called the company just to let them know the issues, but also express some concerns about the use of wooden shims. The sink installation has a one year warranty, but I am still nervous.

Long story short, are wooden shims appropriate in this situation? Will my sink hold up? Should my husband and I just install the sink per the manufacturers instructions?

I attached some photos so hopefully this all makes sense! Thanks for any guidance.

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Comments (5)

PRO
Joseph Corlett, LLC
4 years ago
Your top appears to be engineered stone (quartz). If so, you have just been put out of warranty with the installation of mechanical fasteners directly into the estone. This is prohibited practice by all manufacturers.

Drop the sink, abandon the clips (they are junk and leak anyway) and install a Hercules Universal Sink Harness (BB Industries) or a Sink Strap or two from GranQuartz. Since they attach to the cabinet sides and not the stone, you should get your warranty back.
PRO
Joseph Corlett, LLC
4 years ago
Your sink is ready for use immediately after it's strapped in place.
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PRO
Joseph Corlett, LLC
4 years ago
"Long story short, are wooden shims appropriate in this situation?"

Absolutely not. They willl shrink, crush, and leak.

"Will my sink hold up?"

No. Maybe a week.

"Should my husband and I just install the sink per the manufacturers instructions?"

No. Throw the Kraus clips in the trash please. You should install it per my above instructions. I've strapped thousands of sinks with no callbacks, leaks, or contaminated crud lines between the sink flange and the stone bottom.
Amy Stuart
Original Author
4 years ago
Joseph-

Thanks for responding. My folks have an undermount sink. I had my dad send pictures of the installation and they have the Hercules Universal Sink Harness. The sink has been installed for 3 years and no issue. I wanted to repeat that but had no idea what it was called or where to source it.

Do you have a preference between the two you suggested? The Hercules Universal Sink Harness is available on Amazon, so that is super easy! Are these mounts DIY friendly? I think we are pretty capable. Definitely could rig it the way the installers had it (eye roll), but obviously shims in this situation are far from professional. Any preference on Silicon?

Thanks so much for your advice.
PRO
Joseph Corlett, LLC
4 years ago
Using the HUSH or the Sink Straps depends upon the sink drain configuration predominantly. If you don't have room to get a strap behind the drain, you're probably better off with the HUSH. A beginning/intermediate DIYer shouldn't have any problems strapping a sink. Use 100% silicone and color wise always bring the stone to the sink, never the sink to the stone.