Problems with an undermount sink

Updated February 21, 2017

Installed below cabinetry, an undermount sink sits even with the countertop. This type of sink is generally in kitchens and bathrooms with natural stone and solid surface countertops -- surfaces that can support the sink's weight. Most people prefer an undermount sink to an overmount sink, because undermounts are easier to keep clean. You just sweep crumbs and liquid food spills into the sink without worry the debris will catch on the sink's lip, as is commonly the case with overmount sinks. Despite this benefit, be aware of certain problems with undermount sinks before installing one in your kitchen.

Pulls Away from Countertop

A basic double-bowl sink weighs as much as 45.4kg. when one bowl is full of water and the other bowl has a built-in garbage disposal, according to Ask the Builder. The sink's weight therefore requires correct installation in order to prevent the sink from loosening and pulling away from the countertop. Ask the Builder recommends making certain that the bottom surface of the countertop is completely free of dust before using adhesives, such as epoxies and caulks, to affix metal anchors on the sink to the countertop underside. Dust can prevent glues from forming a secure bond, and thus can cause the sink to pull away from the countertop.


A correctly installed undermount sink is usually leak-free, but leaks can occur when you do not apply a bead of clear silicone caulk to the undermount sink lip. The silicone caulk prevents moisture from penetrating the thin crack that often exists between the countertop and sink and acts as a watertight seal. Although you should always follow the manufacturer's instructions that accompany your undermount sink when installing it yourself, most instructions include the application of silicone caulk, states Ask the Builder. If your instructions do not list this step, contact the manufacturer directly to confirm this step is not necessary.


Homeowners frequently desire undermount sinks because of their streamlined look, in addition to the ease of cleaning. Unfortunately, this value is not without added expense. Undermount sinks usually cost more than overmount sinks and often necessitate an expert to install. An undermount sink of similar size and shape as an overmount sink can cost a few hundred dollars more, according to Service Magic.

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About the Author

Christie Gross has been writing since 1998. Her work writing public policy platforms for elected officials nationwide has been featured in national and local newspapers under various client pen names. Gross has a Bachelor of Arts in English and political science, as well as a Master of Public Administration from the University of Delaware.