How to Waterproof a Cabinet Under a Kitchen Sink

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Cabinets under kitchen sinks are prone to water damage and other things such as mold growth and rot. waterproofing your kitchen cabinets is an essential step in protecting your home from damage, mold, and rot.

If you have ever experienced water damage in your home you know such repairs can be both time and energy-consuming. If you have a leak in your kitchen that is affecting your cabinets, small or large, it’s best to address it immediately to prevent further and greater damage.  

Here I’ve put together a guide to the best ways to do so. 

Here are some ways to waterproof the kitchen cabinet beneath your sink;

Waterproof Wooden Surfaces


Do you have wooden countertops in your cooking space? Waterproofing the kitchen countertop is a great way to protect it from water damage. If neglected water might seep into the surface without realizing it, causing problems with moisture and water damage. Here is a method for waterproofing these surfaces.

Sand the wooden countertop

First, you need to sand the wood down. You don’t have to be too abrasive, but I want a nice smooth surface that is going to adhere to paint very well. 

Apply primer

Next, prep the area with some primer. This liquid helps the color to stick to the wooden material for many years.

Apply Paint of the desired color

Be sure to use a color that is practical for the space you’re in, be sure to apply a couple of coats if it’s necessary. Be careful not to miss any spots!

Apply Clear Varnish

Add top coats of clear varnish which is designed for waterproofing. I recommend using a foam roller to apply it because it helps to spread it evenly and doesn’t tend to leave streaks this way.

Now I am waterproofed and ready for use.

Waterproof Areas Around the Sink


If you have sink like an Acrylic Kitchen sink, you’ll first need to remove the old sealant around the sink. Use a cutting tool to scrape it off from the edges of the sink. If you have trouble removing it, try using a Sealant Remover, as it makes it easier to scrape off.

After complete removal of the old sealant, wipe down the area with a damp cloth. Make use of an all-purpose cleaner to clean the area then use a dry cloth to clean dry. Next, take your silicone sealant and cut the nozzle to the desired width, and get the desired flow.

Then, apply the sealant to the perimeter of the sink until desired areas are completely covered. Be sure to place a small amount of pressure as you run the sealant around the sink.

After you have applied the sealant to the sink’s perimeter, gently press the sealant to smooth it out. Wipe off excess sealant or spill with a damp cloth. Allow the sealant to get dry before using the sink again.

Install Under-Sink Waterproof Mats

After applying sealants and other waterproofing layers, an under-sink mat can also be used to protect your cabinets from water damage. These mats can be easily purchased at local hardware stores or online.

They are basically made of rubber and are also a mess-free way to deal with small spills, they come in a variety of colors and sizes to suit any cabinet type. they are flexible and easy to clean and helps keep the base of your under-sink cabinets free from damage if a leak should occur. 

Caulk Everything

If you own a dishwasher for decades, you would know that liquids can enter your kitchen and cabinet space that is available to them, no matter how small. A great way to protect your cabinets is with the use of caulks and sealants. You might have covered everything, but if small holes exist water can get in, you still risk damage.

Caulking is a perfect method because this material can get into tiny spaces and create a barrier preventing nearly anything from going in. It is particularly good for getting into the joints and edges of your cabinet or lining the seams.

You have several options when it comes to making a selection. Caulks and sealants are nearly the same. 

Caulks are thicker and more rigid, Both have some elasticity, but sealants are more elastic.

Caulks and sealants come made with different materials, such as polyurethane, silicone, and latex. The difference is what you will be using it for, a sealant may be the better option  If the space you are using it in gets a lot of movement since it is more pliable once it’s dried.

Fix Pipe Leaks Early

Apart from damaging your cabinet, Kitchen leaks are a major cause of water waste every year in the U.S. The Environmental Protection Agency (EPA) says household pipe leaks cause more than one trillion gallons of water wasted every single year. You must check your pipes regularly, especially if you travel frequently or if you’re a landlord who lets out to people with high standards.

Old or leaking pipes should be replaced before it’s too late. Your plumbing is a very important aspect of your home’s structural integrity.

Call a plumber if you’ve got leaky pipes and schedule regular plumbing inspections to ensure that your plumbing is working as intended.

How to Check for Leaks

  • Thoroughly Examine areas around plumbing pipes and hoses for signs of moisture.
  • Look under the sink for loose connections in pipes and hoses.
  • Smell for musty odor.
  • Thoroughly Check cabinets, floors, and walls for dark spots or areas of discoloration.

Leaks can come from the plumbing, moisture from ventilation, or even water that splashes on your counter while doing the dishes or washing your hands.

Whatever method you decide to use, I hope that it can help you to better waterproof your property and keep your cabinets safe from damage and decay. 

Brett E.

Brett E. is the Owner of  Brett comes from a long line of craftsman and foreman, and has been involved with the construction and renovation world ever since he was a boy while working for his families construction and remodeling company.  After graduating with a a degree in Interior Design, Brett is the go to guy for any interior design or remodeling questions!