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Flush Mount Vs. Undermount Sink: A Detailed Comparison

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You’re finally ready. You’ve begged, borrowed, and saved, and now you are prepared to revamp the old kitchen or build a completely new one.  You’ve got the layout mapped in your mind and everything from the stovetop to the type of faucet carefully selected.  But now you’re stuck between a flush mount or undermount sink. 

The most significant difference between flush and undermount sinks is that the top of the sink wall of a flush mount sink sits flush with the top of the countertop, with little to seam.  With an undermount sink, the top of the sink wall is level with the bottom of the countertop. 

Both flush and undermount sinks are more expensive than standard drop-in sinks, and both are considerably more difficult to install.  Both are also really stylish and come with lots of great benefits, so which should you choose?

The Big Difference Between Flush And Undermount Sinks

Before you get tangled down a sink-focused rabbit hole, it’s probably important to first understand the differences between the two sinks.  All the pros and cons of each are byproducts of their differences. 

Traditional drop-in sinks are cheap and easy to install.  Buy the sink, trace it out, cut the hole, drop it in, add some silicone, and you’re off to the races.  However, two major drawbacks come from having a large lip that sits on top of your counter.  

This lip not only takes up precious counter space but can also be a mold and grime nest because water and dirt will, at some stage, find their way into the gap between the counter and the sink.  They are also a bit… outdated in terms of appeal. 

Enter the flush and undermount sinks, both of which solve those problems to varying degrees.  

While both look great and clear up countertop space, their big difference is where they meet the countertop. 

Undermount sinks are installed and mounted to the bottom of the countertop.  The top of the sink wall sits against the bottom of the countertop.  The countertop extends over the sink wall, is slightly short of the sink wall, or sits flush in line with the sink wall.  

On the other hand, Flush mount sinks are mounted flush with the top top of the countertop.  A well-installed flush mount sink will have no seam between the countertop and the sink where water and dirt can get lodged.  

Flush Mount Sinks

A single flush mounted sink
Here’s a classic flush-mounted sink where I’m currently staying.

Style is subjective, and what looks good to me may not be so appealing to you, but I have to admit, subjectively, you can’t beat the look of a flush mount sink.  It never likes like an afterthought.  Instead, it looks like the centerpiece around which the kitchen was planned.

However, not all flush mounts are equal, and they definitely come with their fair share of pros, cons, and considerations.

Variations Of Flush Mount Sinks

There are two primary variations of flush mount sinks.  

One variation does not have a lip above the sink wall. It’s shaped like a basin, with the top-edge mounted flush with the top of the countertop. It is a very unique sink, though.

The more common style of flush mount sink has a lip above the sink wall, not unlike a drop-in sink. This lip is recessed into the countertop, creating a continuous surface between the countertop and the sink. It’s this type of flush mount sink which is most referenced in this post. 

Benefits Of Flush Mount Sinks

Because flush mount sinks don’t have a seam between the sink and countertop, it makes cleaning up a breeze.  You can easily wipe debris from your counter straight into the sink.  There’s no lip to catch crumbs or brew mold.

You also generally get more countertop space, depending on what style of sink you choose.  If you select a sink with an integrated area for drip-drying dishes, you will sacrifice some countertop space.  However, this drip tray can still be used as part of the countertop because it sits flush.

Flush mounts win the space battle (compared to an undermounted sink) underneath the sink, in the cupboard.  The fact that the flush mount sink sits in line with the top of the countertop means that you gain the width of your countertop in packing space below the sink.  

Finally, flush mounts can also be installed in almost any countertop material from granite to laminate, making it a viable option for most kitchens. 

Cons Of Flush Mount Sinks

The first snag of flush mount sinks is that they are only made with specific materials, and you can very rarely buy one off-the-shelf.  You will likely have to order one specific to your kitchen, increasing the cost and time to complete the project.  

Although waiting for a new sink in a new kitchen isn’t the end of the world, having to wait for a replacement sink in a working kitchen of a family of four can quickly end in civil war. 

Furthermore, the hole and recess in your countertop are uniquely cut to fit a particular sink.  As a result, you cannot change your sink without changing your countertop unless you find a sink with the exact same dimensions.  

If you are afraid of commitment, perhaps you should steer away from the flush mount sink.  

Installing A Flush Mount Sink

Installation of flush mount sinks is just plain tricky, with the difficulty level ranging from “hard” to “just-give-up-already,” depending on the material of your countertop.  

It will be easier to install if you have a laminate countertop because the recedes for the sink lips can be cut in using a router.  Granite or cement countertops, on the other hand, will be a lot harder.  

I would strongly suggest having your sink installed by a professional.  Yes, even if you have opted for laminate tops and own a router.  

The problem is that the tolerances you are working with are incredibly tight.  Cut the recess slightly too big or too deep, and you risk having to throw away a whole countertop.  

Cost Of A Flush Mount Sink

Flush mount sinks that are made-to-order will set you back an X-Box 360 and a few games.  Expect to pay upward of $500, excluding installation, depending on the size, shape, and material.  

Factor into that installation difficulty, which will naturally yield a higher installation price, and you’ve got yourself a pretty expensive sink right there.  Emphasis on both “pretty” and “expensive.” 

Buy Your Flush Mount Sink on Amazon (this is a paid link).

Undermount Sinks

An undermounted sink
This is a deep under-mount sink. As you can see it offers a cleaner look than the flush mount sink above.

Undermount sinks seem to breathe class.  And even though I prefer the visual appeal of a flush mount sink, you really can’t go wrong with an undermount sink.  

If an undermount sink is what you are leaning towards, make sure you choose the best variation.

Variations Of Undermount Sinks

There are three primary variations of undermount sinks, or variations brought about by how the sink is installed.  

The first variation is a flush-mounted, undermount sink: not to be confused with a flush mount sink.  This variation has the hole in the countertop cut precisely the same size and shape as the sink beneath it.  

The second installation variation is called “positive reveal.” In this case, the hole in the countertop is slightly bigger than the sink, which means a small section of the sink lip or upper edge of the sink wall will be visible.  

The final variation, and the safest, in my opinion, is the “negative reveal,” where the hole in the countertop is smaller than the sink, leaving a slight overhang over the sink wall.  

I have listed a few important pros and cons of these variations below. 

Benefits Of Undermount Sinks

When it comes to countertop space, undermount sinks are the raining kings of the kitchen.  

In the arena of countertop cleaning, it shares the benefit of a flush mount sink.  In fact, if you have a negative reveal, it could even outperform the flush mount sink in the cleanliness department. 

If a flush mount sink is not installed correctly, there could be a slight seam for crumbs and liquids to get into, but this is not the case in a negative reveal undermount sink.  The countertop extends over the sink wall, making it difficult for anything wiped into the sink to find its way between the counter and the sink. 

Should you have a positive or negative reveal, replacing the sink is also easier than a flush mount because the hole has not been tailor-cut and recessed for any specific sink.  Undermounted sinks are also more commonly used and readily available off the shelf.  

Lastly, although you do lose a bit of space in the cupboard below, you also end up with a “deeper” sink because the countertop, in effect, forms part of the sink.  The added space will help with washing large pots, for example.  

Cons Of Undermount Sinks

Let’s cover the variations first, as some of them come with cons specific to them. 

If you opt to go for a flush mount installed undermount, you will be left with the same replacement challenge as with a standard flush mount, in that the shape of the hole is now uniquely cut to fit the sink.  

This challenge can be overcome, to an extent, by buying a sink slightly bigger than the hole, should you need to replace it and can’t find the exact same one.  

I would advise against a positive reveal as it runs the risk of nullifying the biggest benefits of an undermount sink.  A positive reveal creates exposed the sink lip below the countertop.  This lip becomes a ripe opportunity for water penetration, mold growth, and dirt build-up.  

Regardless of which variation you opt for, a significant downside of undermount sinks is that you cannot, or rather should not, install them in laminate countertops.  Undermount sinks leave the edge of your countertop exposed, which won’t be waterproof in the case of a laminate countertop. 

In other words, by opting for an undermount sink, you are limited to entirely waterproof countertop materials such as granite and concrete, vastly increasing the price of your new kitchen.  

Installing An Undermount Sink

Although the tolerances aren’t as tight as with a flush mount sink, the fact that you need to use a more expensive countertop material means that you are still better off paying a professional to install it or run the risk of ruining a very expensive slab.  

Furthermore, the inside edges of the hole will be exposed and must be carefully cut, finished, and carefully polished to match the rest of the countertop.  You do have the option to have the hole professionally cut and finished, and then installation of the sink can be done by yourself and with little risk. 

Cost Of An Undermount Sink

Proper undermount sinks can also be expensive, quickly hitting prices higher than $800, excluding installation.  Fortunately, they are more common, so you could pick up a bargain if you shop around enough.  You are also likely to pay slightly less for installation.  

Buy Your Undermount Sink on Amazon (this is a paid link).

Two Tips To Save You Money

I will provide a few money-saving hacks and a tip for both flush mount and undermount sinks to help you with your decisions. 

In the case of flush-mounted sinks, you can save a few dollars by not buying one.  I mean, not a specifically designed flush mount sink.  You can actually flush-mount a drop-in sink as long as the sink has square edges on the lip instead of rounded bevel edges.  

Admittedly it’s rare to find a budget sink that can be flush-mounted, but it is possible and installed correctly, you can even fool the fanciest of dinner guests. 

Here is a video showing you how:

Fit Franke First - How to flushmount a sink

When it comes to saving on an undermount sink, many claim it is entirely possible to undermount a drop-in sink.  Yup! It can be done.  Ensure that you have good sink support installed, use high-quality mounting brackets and be generous with the sealant.  

This hack does come with a few downsides, in that it will be more challenging to install, could be prone to leaking, and not quite as strong, but if you are desperately wanting that drop-in sink and can’t afford it now, this may be an option for you to consider.  


Both flush and undermount sinks are great options that look amazing.  Both are easier to clean, have less mold build-up, and are unrivaled in countertop space.  Both options are also a lot more expensive and difficult to install than drop-in sinks. 

Because they have more-or-less the same significant benefits over drop-in sinks, your choice is likely to be made by which material you are using for a countertop, which has drawbacks that are deal-breakers to you, and, most importantly, which one looks the best. 

Next, you can learn if touchless faucets are worth the investment.

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