Under-Mounting a Top-Mount Sink

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Installer gets advice on mounting a new-fangled "hybrid-mounting" sink. June 17, 2005

I’m a one person shop, in the middle of a cabinet installation, and I recently fastened down the countertop underlayment in preparation for a granite countertop to be installed. I knew my client wanted an undermount sink and he recently purchased one (our local granite company recommends that they only come out to measure for the stone with exact cutouts and undermount sinks in place).

I arrived at the house yesterday, took one look at the (quote) American Standard “self rimming” sink sitting on the countertop and said “that’s not an undermount.” The owner replied “the display at Home Depot said it could be undermounted.” Thinking he was mistaken and it had said something along the lines of “undermount model available”, I swung by the store and sure enough, affixed on what to me looks like a typical drop-in type self rimming sink is a sticker stating “this sink can be undermounted with an optional kit.”

This one is new to me. In my experience, sinks are either undermount models or not. I’ve never come across such a hybrid before. I thought undermounts typically have a large, flat, often thinner flange with an unfinished edge and come with brackets and installation instructions included. I informed the owner that I wouldn’t feel comfortable cobbling this sink into his very expensive kitchen and preferred that he return it and purchase a sink manufactured specifically for that application.

Am I totally behind the curve here? Is this the wave of the future or (as I see it) a not too well thought out marketing ploy? ("Let’s not bother to tool up for a different sink, just throw in a couple of brackets and call it an undermount...")

Forum Responses
(Cabinet and Millwork Installation Forum)
Re: Sink installation question Paul in Fla. 7/2
Sounds like the marketing wizards have struck again. You know the old adage about if you try to "build something to do many things it will end up doing nothing well." Sounds to me like the homeowner is "pennywise and pound foolish." Recommend that he spend a few extra bucks and get a quality product that will last and be what it should be.

On American Standard's site, I found install instructions for the sink I'm guessing your customer purchased. It can be tiled in or undermounted two different ways. You do need clips though, and the instructions aren't clear about whether they are included or not.

Most any sink can be undermounted. Don't make such a project out of it. The main requirement is adequate support. Do what you need to support it so that the top of it is flush or slightly lower than your 3/4" roughtop. I usually rout the plywood 7/16" or so and add cleats on sides that will carry weight. I've had many requests to undermount with the option of removing the sink from below in the event the sink needs replacement. That's a whole new batch of headaches.

Undermount Sink Setters will make your life much easier. You can get them from specialtytools.com.