Undermount Sink Cutouts – What You Need to Know

Undermount Sink Cutouts – What You Need to Know

Undermount sinks, including farm and apron styles, are by far the more popular option for kitchen sinks these days. An undermount sink is any sink that mounts to the underside of the countertop, rather than dropping in on top of the counter. Besides looking beautiful, undermount sinks also have the advantage of providing a smoother clean-up process – simply wipe crumbs and scraps right into the sink, without getting anything caught in the rim like you would with a drop-in style sink.

While we love undermount sinks, they do require extra care when installed in a butcher block top… We’re here to help you before you install.

Your sink cutout can be done when your countertop is manufactured, so that it is installation-ready when you receive it. Undermount sink cutouts void the manufacturer’s warranty whether done at the factory or onsite, so it is important that the cutout is done right! Read our previous post, Custom Countertops from Start to Finish, to see the process involved in making your top.

An undermount style sink installed in a butcher block top will leave wood edges exposed to water, which means a higher potential for water damage than if you use a drop-in style sink. Before you install, it is very important that you are mindful of this potential damage, that you prepare the edges in advance, and do your best to avoid exposing those edges to splashes and standing water when in use.

No matter if your cutout is DIY or factory done, you need to take extra precautions when installing your sink to protect the exposed edges of the cutout:

undermount sink
  • If you have a polyurethane or varnish finished top, apply extra layers of finish on the underside of the counter, several inches around the perimeter of the sink cutout. This will help avoid any moisture damage if there are leaks in your sink or faucet. You must apply additional coats of poly to the exposed cutout edge itself to give it more water resistance.

undermount sink
  • For oil-finished tops, use an oil-based poly on the underside. For the exposed edges, you must apply melted beeswax or paraffin wax to repel water. It is important to reapply the wax occasionally to maintain water resistance. Alternatively, you may use an oil-based matte poly finish on these edges, but we recommend you test in an inconspicuous area first to be sure you are happy with the look.

Whether you choose to do it yourself or go with a factory cutout, we are here to help! Give us a call if you have any questions or concerns, and our experts will help you decide the best option for your home and lifestyle.