Bathroom Vanities - Under Mount Sinks

[George Bokros]

Going to be building a new vanity for the bath this fall. I have never seen or worked with an under mount sink. I am wondering how they mount, do they mount to the cabinet or to the top?

I am thinking about this so I can design the vanity to work with the sink.

Thanks

George

P.S. We have not even looked at sinks yet so perhaps my question is moot if we shop for the sink.

[John R Hoppe]

How the under mount sink fastens to the countertop will depend on the material. With solid surface materials like Corian, they would be glued to the top, and usually blended in during the fabrication process. With Granite or "Quartz" materials like Silestone and Cambria, small holes are drilled in the underside and fasteners are glued in place, then the sink is clamped in place, and a bead of silicone is applied to the inside to make it water tight.

If you are designing the vanity cabinet, I strongly suggest you discuss the project with the countertop fabricator, and have the sink and the faucet in hand before you cut anything. The top and sink MUST to fit into the vanity in order for this to work. DO NOT forget to allow room for the faucet assembly and the required holes. Don't forget that the back and side splashes will typically be 1" or thicker when using stone (ask your fabricator) and cabinet sizing will need to accommodate that to allow the faucet to fit. In my experience, the fabricator's installer's best friend is a Sawzall and they will use it to make things fit.

[scott vroom]

I've installed heavy porcelain undermount sinks on both granite and silestone using a 2-part epoxy and clips like these:

[Floyd Mah]

I just finished a vanity with twin undermount sinks. The sinks can be epoxied to the underside. The store that I got the sinks from sold me a bucket of epoxy for about $45. I thought that was a lot, but the epoxy is very strong. I had a granite top and glued the sinks in place. Did not use mounting hardware since I covered more area with the epoxy than I would have if I had just glued in four fasteners. If you examine most of the vanities in places like Home Depot and others, you will discover, as I did, that I could make a much more substantial vanity than I would have bought. Just use a full sized plan to plot the layout of the sinks and faucets.

[Mike Cutler]

George

The sink is mounted to the underside of the counter surface with a system of adhesive and clips.
If you're buying a new sink, the mounting and installation instructions will be in the box, but sometimes the clips aren't. If it's a Kohler sink, you can go to their website and download any of their sink installation guides and the templates for the required cutout(s), and clip placement. It's actually a pretty nice resource, because you can build everything prior to installation and know that it will fit and be mounted properly without ever leaving the house. Remember to also factor in your faucet(s) placement.

[Dave Zellers]

So the main answer to your question is, the sink attaches to the top. If the countertop is wood, it just screws on with clips. I didn't even bother to caulk it and don't regret it at all. The water that ends up on the counter of a lavatory sink is usually no more than a few drops unlike a kitchen situation.

counter.jpg

[Erik Loza]

They used epoxy on ours. No fasteners.

Erik Loza
Minimax USA