Kitchen Sinks and Their Cutout Types

In the stone industry, particularly concerning natural stone benchtop installations, the terms “drop-in sink,” “undermounted sink,” and “flush-mounted sink” refer to various integration methods between the sinks and the benchtop materials. The benchtops might be made of Marble, Granite, or Quartzite stone. Each sink method has its own installation requirements, as well as features that affect its appearance and performance.

Top-Mount Sink (Drop-In Sink)

A drop-in sink is built to be installed from above the countertop. It has a distinct rim or lip that is above the countertop surface around the entire perimeter. This rim space supports the sink’s weight and prevents it from falling into the under-cabinet space. The lip then holds the sink in location.

Kitchen Benchtop cutouts for drop-in sinks are intentionally smaller than the sinks themselves. Why? Because we need the sink’s rim to cover the edge of the cutout to keep water from seeping underneath. Because of this, we can be a little sloppy with the cutout and not as precise. After all, the rim will cover any errors.

Drop-in sinks are gaining popularity for do-it-yourself projects and are much easier to install and replace. They can work with any benchtop material; however, they can accumulate debris around the lip where the sink meets the benchtop.

Undermounted Sink

An undermounted sink is installed beneath the countertop. The edge of the countertop material forms the upper perimeter of the sink, and there is no visible rim on the countertop surface, which produces a clean look and a seamless transition between sink and countertop.

The look is sleek and uninterrupted, which makes it easy to clean; you can sweep debris directly into the sink without encountering a rim where stuff can lodge and make a mess. Of course, that also means the sink has to be installed more precisely than a rimmed one, and it costs more, too. Still, if you have a solid surface—meaning easily machined stone, like granite or any number of solid-surface substitutes—under your kitchen sink, this is the minimum you should expect in the way of appearance.

Note: A rim is not the same thing as a lip. Both are edges that project outward, but a lip has an upper surface that is accessible without tilting or reaching; a rim is only partially accessible without leaning over. The undermount sink cutout must be precise. Its exposed edges call for accuracy.

Flush-mounted Sink

A flush-mounted sink is made to sit level with the benchtop. When you see it, it looks like the sink and benchtop are one continuous surface. Still, there’s a little secret this installation method shares with drop-in sinks: It’s technically an above-mounted sink. Yet, it takes the appearance of an undermount sink and offers a smooth, seamless surface at the intersection of sink and benchtop.

Like an undermount sink, a flush-mounted sink requires nearly perfect precision in the cutout. This is because the visible parts of the cutout and the edges of the sink must align so well as to be nearly indistinguishable, especially because sinks are often mounted slightly below the benchtop surface, in a way that makes them seem to be, well, flush with the benchtop.

A flush mounted sink gives a modern and unembellished look, allowing easy hygiene while offering a visually appealing transition from sink to countertop. Demands precise construction and setup, making it generally pricier than the other two options. Distinct aesthetic and functional benefits accompany each of the sink installation methods. The choice between them often comes down to style, material, and budget. Each installation method serves the sink well and showcases it beautifully—if the right method is used for the right reasons.