Are My Bathroom Tiles Waterproof?

Are Bathroom Tiles Waterproof


Waterproof bathroom tiles are a great way to protect the structure of your home from mold and mildew while creating a stylish look.

Most bathroom tiles are not waterproof unless they are treated with a glaze before they are baked in the kiln. Glazed tiles will still retain some water, but the denser the tile is, the less water it absorbs. Unglazed tiles should be treated with a sealer to protect the tile.

According to Wikipedia, the definition of “waterproofing” is “the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water.” By this definition, we certainly need waterproof tiles in our bathrooms to prevent any damage from moisture!

So what can we do to protect our bathroom walls, given that most bathroom tiles are not waterproof? In this post, we’ll explore why waterproofing your bathroom requires:

  • Sturdy tiles that are glazed or sealed.
  • Waterproof barriers beneath wall coverings and on top of substrate walls and floor.
  • Grout and grout sealer.


Pro Tip: Any bathroom tile project requires a great bathroom tile calculator to help you figure out how much tile to order and what it will cost. Fill out the form below and I’ll send my free tile calculator straight to your inbox.



Waterproofing Bathroom Tiles: 6 Key Concepts

Bathtub - One of the Best Locations for Accent Tile in the Bathroom


Contrary to popular belief, most tiles are not waterproof at all. To better understand the topic of waterproofing bathroom tiles, let’s take a look at some key definitions:


Water-Resistant TilesResist water, but water can still penetrate and eventually cause damage. The results can be uneven floors and walls, wood rot, mold, and mildew.
Waterproof Tiles

Withstand or repel water and protect the house's structure by preventing water damage.
Non-porous Tiles

Do not allow water to seep in either because they’re made of densely packed material or they’re covered with a protective coating to prevent water from seeping in.
Porous TilesAllow some water to seep into the gaps in the material.
Glazed TilesA liquid glass is applied to man-made tile materials before they are placed inside the kiln. The glaze fuses to the tile's surface during the firing process creating a hard coating that provides water-resistance or waterproofing.
Unglazed Tiles The surface of these tiles are not coated with the glaze, leaving the tile porous and water absorbent.


And be sure to check out my ultimate guide to bathroom tile, which includes resources about bathroom tile materials, bathroom tile colors, tile finishes,  waterproofing bathroom walls and tile, grouts, sealants and more. 


What Happens If You Don’t Use Waterproof Tiles In Your Bathroom?

leaking bathtub floods bathroom


You might wonder where that damp smell is coming from in your bathroom – it could well be because of the dampness that has built up out of sight behind the tiles. 

Some areas take longer to dry than others, and it’s these areas that are not too well ventilated, which could cause problems in the bathroom space by retaining moisture and causing the areas behind the tiles to rot.


Breeds Bathroom Mold and Mildew

Breed Bathroom


If water seeps or leaks through the tiles or grout into the house’s structure, mold and mildew will thrive, creating an unhealthy environment.


To find out if there is mold under your tile, read the post Is Mold Lurking Under Your Tile?


(And if you already have a bathroom mold problem, be sure to read my battle plan to destroy it.)


Causes Structural Damage

Causes Structural


Hidden water damage is dangerous and could affect the structure of your home or cause warps and bubbles in drywall or loosen tiles, making them dangerous to walk on.

Keeping your bathroom free from moisture is the best way to prevent long-term damage to your home and to prevent the risk of mold-related illnesses to your family.


Blows Your Budget

A pile of 100 dollar bills


Using tiles that aren’t water-resistant or waterproof should not be a consideration for the bathroom – the disadvantages far outweigh the benefits and could affect your budget in the long run with unnecessary maintenance.

But maybe you’re considering painting the bathroom instead. If so, be sure to read my post To Tile or Paint the Bathroom? The Clear Winner.

Regularly add sealant to the tiles to provide extra protection against moisture. My Tile & Grout guide offers great tips on how to seal tiles.


Tile Density or Water Absorption

Stonetiledepot - Ceramic Wall Tile Thickness in Bathroom
See the stunning Pure Wall Tile Ceramic Collection at Stonetiledepot.


All tiles will retain some water. How much water they retain is determined by the density of the tile. The denser the tile is, the less water it absorbs. This means that less dense tiles will absorb water, and the water can seep out and into the substrate, causing water damage.

Tile manufacturers determine the density of a tile (or how much water the tile can hold) by weighing the tile, submerging it in water for two minutes, and then weighing it again. The absorption is determined by the difference in the two weights. 

The ANSI (American National Standards Institute) places tiles into 1 of 4 categories according to the rate of water absorption:


  • Non-vitreous – absorbs >7% of its body weight


  • Semi-vitreous – absorbs between 3 and 7% of its body weight


  • Vitreous – absorbs between 0.5 and 3% of its body weight


  • Impervious – absorb <0.5% of its body weight 


The lower the rate of water absorption, the better the quality of the tile. Tile products like porcelain and ceramic are great for use in the bathroom due to their low water absorption rate.

Read through my article 17 Beautiful Bathroom Materials for great ideas on choosing the perfect bathroom tile for your space. And be sure to cross-check your favorite tile materials with this list of the most popular bathroom tiles and their water absorption rates:


Tile typeWater-resistantWater absorption rate
Glazed ceramicYes3 – 7%
Unglazed ceramicNo3 – 7%
Glazed porcelainYes0.5%
Unglazed porcelainNo0.5%
Sealed TravertineYes3 – 7%
Yes3 – 7%
CementNo3 – 7 %


How to Know If Your Bathroom Tiles Are Water-Resistant

Small bathroom with subway tile


The easiest way to check if your bathroom tiles are indeed water-resistant is by touching them. A glazed tile has a smooth, polished finish. 

Of course, you may need to give the tile a good clean first, as years of dirt and grime could accumulate on the tile covering the finish, making it feel rough or sandy, masking the smooth finish.

Unglazed tiles will feel rough and sandy.

If you are remodeling your bathroom and are picking out new tiles, checking for glazed or unglazed tiles is easy. Simply pick up the tile and take a good look: Glazing will only partially cover the edge of the tile, so if the bottom of the tile is a different color from the top, the tile is glazed.

Unglazed tiles are solid colors all the way through.


Can You Waterproof a Shower Without Ripping Out Tile?


YouTube video player

While experts state that waterproofing over an existing area might not be the way to go, not everyone agrees.Watch this creative and informative video on waterproofing over an existing area in 3 minutes!

That said, most experts agree that there is no way to fully waterproof an area after the tiles have already been installed… unless you rip everything out and start again and lay a waterproofing membrane first! The best way to ensure that the bathroom is fully waterproofed is to take steps before the tile installation begins. 

However, you can attempt to replace the tile and grout with new tiles, new grout, and a sealant. While this method is not guaranteed to waterproof the area, it might make the space more water-resistant and could buy you time while you plan for the bigger job of waterproofing the entire area.



How to Install a Waterproof Membrane

Waterproof Bathroom Tile Membrane


Although waterproof tiles are a great way to keep humidity and moisture under control in the bathroom, they are not the only way to protect the area from damage.

The best way to waterproof the bathroom is by treating the area with waterproof membranes before beginning the tile installation. This job is best undertaken by a professional.

There are several different types of waterproofing materials that you can use behind the tile. These include cement tile backerboard, liquid waterproofing membranes, and fabric waterproofing membranes.

To learn much more, read my post How to Waterproof Shower Walls Before Tiling

How to Repair Bathroom Tile Cracks

Waterproof Cracked Bathroom Tiles


If you notice stains forming on the ceiling below a bathroom, chances are that cracks have developed in the tiles or grout surrounding the shower or tub, allowing moisture to seep through. 

Leaks and dripping water can cause extensive damage to your bathroom and your budget!

To keep the tiled areas in top shape requires maintenance. If you are a general DIYer, then small jobs should be easy enough for you to handle, but if the leak or damage to the space is too big for you to attempt, call in the professionals.

Either way, the first step is to check and seal the grout around the tiles. The second step is to replace broken or chipped tiles:

  1. Inspect the grout around each tile.
  2. Wipe away soap scum and mold.
  3. Remove all loose grout with a flat-head screwdriver or a grout saw until you reach the solid grout.
  4. Apply new grout using a sponge and wipe off the excess.
  5. Check and replace the old caulk around the floor of the tub, shower floor pan, faucets, and tub spout – make sure you use a good amount of silicone caulk to prevent water from seeping behind the tiles.
  6. If the cracks in the tile are small enough, fill them up with new grout. If the tile needs to be replaced, chip away the old grout and tile adhesive and replace it with a new tile.
  7. Cover the tiles and new grout with a layer of sealant.

Pro Tip: Apply sealant to unglazed tiles before replacing the grout, in order to prevent the grout from staining the tiles

Read my article on How To Make Thin Grout Lines In Your Shower for a few tips on how to grout your space.


Should You Waterproof The Entire Bathroom Before Adding Tiles?

Bathroom Tile Materials


Adding a waterproof barrier to the bathroom is good to practice and should always be a requirement before adding tiles to any area. A waterproof barrier protects against:

  • Water damage to the structure of your home, preventing or reducing costly repairs


  • Mold and rot, which can cause respiratory problems to susceptible family members


To learn how to tell if there is mold under your tile, read the post Is Mold Lurking Under Your Tile?


  • Pests! Certain pests live in moldy areas, so adding a waterproof barrier reduces the risk of pests and bugs.


Adding a waterproof barrier can also add value to your home. To motivate you to add the waterproof membranes beneath any bathroom wall coverings or floor tiles, read my post about how much a bathroom is worth on appraisal.


Should You Seal the Tile Grout?

creating thin shower grout lines with spacers


Tiles made from glossy materials like glass and glazed ceramic tiles don’t need to be sealed, while unglazed tiles and natural stone tiles do need to be sealed. The grout that runs between your tiles to hold them in place almost always needs to be sealed as well.

Let’s clear up which types of bathroom tiles and grouts need to be sealed in order to resist damage from mold or cleaning agents.


SEALPorous, Unglazed TileCement & Sand Grout
DON'T SEALGlossy, Glazed TileEpoxy-Based Grout (Sealing is Optional)


For much more on how to seal grout and tile, read my comprehensive post Don’t Forget the Sealer| Tile & Grout Guide.

So, Are All My Bathroom Tiles Waterproof?

Stonetiledepot - Green is a great bathroom tile color
Check out the vibrant colors of the Let it Bee Ceramic Collection at Stonetiledepot.


Not all tiles are equal when it comes to waterproofing. Most are better thought of as water-resistant than waterproof.

The best and most effective way to keep moisture from damaging your home and creating nasty environments for mold and mildew to breed is simply by preparing a waterproofed area before installing tiles.

A good waterproof foundation, sturdy tiles, grout, and a good sealer will go a long way in preventing water damage to your home.

To get your tile at up to 40% off retail prices, check out the great selection at

And if you’re about to start a bathroom remodel project, don’t miss out on my free Save Big $$$ Cheat Sheet. You’ll get designer hacks that can literally save you thousands of dollars. Just fill out the form below.  


Tags: are bathroom tile waterproof, bathroom floor tile, bathroom tile, bathroom tile budget, bathroom tile material, tile grout


Shana Burg is a bath enthusiast, content strategist, and award-winning writer. She is the founder of

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