How to Seal Grout

by Michael Franco
close up shot of white square tiles with broken grout

When it comes to home improvement projects, what you’re willing to tackle as a DIYer depends on all sorts of factors, like time, money and confidence. What seems like a no-brainer for one homeowner may feel prohibitively intimidating to another. That said, there are plenty of home projects that even the most novice of DIYers should be able to tackle successfully without too much stress. Sealing grout is one such project.

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Even if you don’t feel up to laying tile or grouting, sealing grout is a pretty straightforward process that helps protect the color and integrity of your grout, by preventing staining and mildew buildup.

How to Choose Grout Sealer

The most important thing to know when sealing grout is what kind of sealer to use for your project. Not all sealers are created equal, and some are made to work specifically with marble and natural stone, whereas others are best suited for ceramic tile. Additionally, some sealers can handle more moisture, which you’d need for shower tile sealing projects more than you would for a kitchen backsplash.

There are two main types of sealers: penetrating sealers and membrane-forming sealers.

Penetrating Grout Sealer

Penetrating sealers use small pieces of latex or silicone to actually permeate the grout to protect it from moisture and staining. Penetrating sealers are long-lasting and work well in damp areas, so it’s the best sealant choice for shower walls or bathroom floor tiles.

Membrane-Forming Grout Sealer

The other option is a membrane-forming sealer. Membrane-forming sealers don't permeate the grout but rather create a protective coating on the surface to keep water out. These sealers can work well in kitchen areas, but should not be used in spaces exposed to lots of water. Any water that gets trapped underneath the membrane will have trouble evaporating, which can cause staining and mildew buildup. These sealers can sometimes be colored, so they can be a great option if you’re looking to change the look of your grout. Membrane-forming sealers work well with unglazed stone, but they won’t work with ceramic or glazed tile because they won’t adhere properly.

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How to Apply Grout Sealer to Tile Surfaces: Step by Step

Once you’ve figured out which sealer will work best for your project, you can get to work. Aside from the sealer, you won’t need much in the way of specialty tools, but it will be handy to gather a few materials you probably already have lying around the house. Note that some of these materials are only necessary if you plan on cleaning your grout first, so you won’t need all of these if you’re sealing newly laid grout for the first time.

Tools and Materials:

  • Sealer
  • Toothbrush
  • Dish Soap
  • Vinegar
  • Clean cotton cloth
  • Sponge
  • Applicator bottle

Step 1: Clean Existing Grout

If you’re resealing your grout as part of a tile and grout refresh, make sure to clean your grout beforehand so that you’re not trapping dirt and stains underneath the new sealer. You can use a toothbrush dipped in soapy dishwater for this step. For tougher stains, you can try mixing equal parts vinegar and water and scrubbing with that solution instead. You’ll want to give the grout time to dry after cleaning so that you’re not sealing any excess moisture in.

If you’re applying sealer for the first time to new grout, you can bypass this step–just make sure the grout is fully dry before applying sealer! Plan to wait a full 48 hours for your grout to dry before applying sealer.

Step 2: Apply Coat(s) of Sealer

If you’re applying sealer over natural stone to help seal it as well, you’ll likely want to use a sponge to apply the sealer so you can cover a lot of ground at once. If you’re working directly on grout lines and glazed tiles that the sealer won’t adhere to, you’re better off using a sealer applicator bottle to help guide your sealant placement.

Apply the sealer carefully, making sure all grout is covered. Let sit for about 10 minutes, then wipe off excess sealer with a dry cloth. Make sure not to miss this step, or your tiles will be left with a foggy haze that’s really hard to get off.

Wait about an hour and then apply a second coat, repeating the steps above. Depending on our project and materials, you may need one to three coats of sealer to get the job done.

Step 3: Test Sealer

To test the sealer, try sprinkling a few drops of water onto the surface after it’s had time to dry. If the water beads up nicely, then the sealer is working as it should. If the grout absorbs some of the water, you’ll probably need to apply another coat.

Step 4: Allow to Dry

Before you resume walking on or showering in the newly sealed area, make sure the sealer has had time to fully cure. Some sealers take 24 hours, but others need a full 48 hours, so check your sealant’s instructions to be safe. Once it’s cured, you can get back to enjoying your space, knowing that your grout is protected from stains and water penetration.

Grout Sealer For the Win

Sealing your grout helps protect it from stains, discoloration and mildew, keeping your tiling project looking fresh and clean. Plan on cleaning and resealing your grout lines every three to five years to maintain your tile’s good looks and longevity.