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How to Choose the Correct Tile Adhesive or Mortar

Thinset vs. Epoxy: Which Is Best for Your Tile Project?

Man applying tile adhesive

The Spruce / Ashley Luciano

Determining which tile adhesive to use for your tile project is the key to installing tile that lasts for decades rather than years. The choice between thinset mortar and epoxy mortar, two common types of tile adhesive, will yield different levels of water resistance, chemical resistance, and strength. Additionally, the learning curve for the application of epoxy mortar vs thinset may surprise you, so it's worth knowing what you're getting yourself into before starting your tiling project.

Fortunately, choosing tile adhesive vs mortar can be a lot simpler than you might think. In most cases, the tile application—where the tile is installed—clearly determines the best mortar option. And sometimes the type of tile itself is a determining factor. Below, we've outlined the most common tile adhesives to help you determine which type is best for your project.

What Is Tile Adhesive?


Tile adhesive is any medium that adheres tile to a substrate. It must be easy to work with, and it must adequately fill in gaps between the tile and the substrate. It cannot cure too fast: Otherwise, you do not have adequate working time. But if it cures too slowly, it takes forever to get to the grouting stage.

Thinset Tile Mortar

Thinset is a mortar that is made of Portland cement, silica sand, and moisture-retaining agents. Thinset mortar is your default tile mortar for most indoor and outdoor applications. Thinset tile mortar has a smooth, slippery consistency, similar to mud. It is applied to the substrate with a notched trowel.

Pros
  • Tight bond

  • Easy to work with

  • Resists moisture

  • Helps prevent mold growth

Cons
  • May crack

  • May need additives to achieve full strength


The best uses for thinset tile mortar include:

  • Shower pans and walls
  • Bathroom floors and walls
  • Kitchen floors
  • Countertops
  • Living area walls and floors
  • Any floor or wall that requires high water-resistance

Standard and Pre-Mixed Thinset

Standard thinset comes as a bagged powder that is mixed with water. The mortar begins setting once it is mixed, so you have to use up the entire batch or discard any excess.

Premixed thinset comes in big tubs and is ready to apply right out of the package. Even though it is heavy to carry and more expensive than dry mortar mix, the ease and convenience of premixed thinset mortar make it ideal for DIYers. Use premixed mortar for spaces such as small bathrooms, mudrooms, or utility rooms. If you are dealing with multiple spaces, then you may want to consider a dry mix to save money.

Working With Thinset Mortar

Thinset tile mortar provides a very strong bond and is resistant to moisture and mold growth. Thinset is also heatproof, so it will not lose its grip in hot environments. Because it is cementitious, thinset is dimensionally stable—it will not shrink or contract.

Another advantage of thinset is that it allows you to level uneven surfaces to some degree. You cannot level wildly out-of-level surfaces, but you can bridge gaps and compensate for slight level changes. 

Because thinset is not affected by moisture, it is best for floor tile and any tile in wet areas, including shower floors, walls, and ceilings and tub surrounds.

Since thinset tile mortar may crack, you may wish to mix it with a special latex additive to increase its strength.

Epoxy Tile Mortar

Epoxy tile mortar is a non-cementitious tile adhesive that comes in two or three separate components that must be mixed by the user right before use. Relative to thinset, epoxy mortar sets quickly, allowing you to get to the grouting of the tile within just a couple of hours. It is impervious to water, so it doesn't need any special latex additives, as does some thinset.

Pros
  • High compressive strength

  • Sticks well to resin-backed stone

  • Strong bond

  • Works with damp surfaces

Cons
  • Needs higher temperatures for installation

  • Higher priced

  • Strong smell

  • Sets quickly

Epoxy mortars work well for porcelain and ceramic tile, as well as for glass, stone, metal, mosaic, and pebbles. Epoxy mortars can even be used for installing rubber flooring or wood block flooring.

The best uses for epoxy tile mortar include:

  • Pools and pool decks
  • Industrial and commercial settings such as labs and kitchens
  • Areas requiring chemical-resistance
  • Consistently wet areas
  • High-traffic areas

Working With Epoxy Tile Mortar

Epoxy-based mortars have high compressive strength and stick well to resin-backed stones. These mortars are simple to use and maintain. Mechanical strength is strong, so they hold the tile firmly in place and resist compression. Pigmented epoxy mortars do not leak onto ceramic or porcelain tile. Epoxy mortars are resistant to a wide variety of chemicals.

Temperatures must range between 60 and 90 F for proper installation. Warmer temperatures speed up curing time; cooler temperatures slow it down. Installation can be made on a damp surface, but new concrete must cure for at least 28 days before adhering the tile.

Tip


Due to the difficulty in mixing and working with epoxy mortars, they tend to be used by professional tile installers more than by DIYers.

On the downside, epoxy mortar is more expensive than thinset and has a strong smell while it cures. Additionally, epoxy mortar sets quickly. This can be a deficit because it provides only a short window of time to make changes. Pot life for most epoxy tile mortars is about 45 minutes. After pot life expires, the product is considered to be unusable.

Mastic Tile Adhesive

Mastic is a vague term that generally refers to fast-grab glues for tile. It isn't cement-based like thinset and doesn't require mixing reactionary compounds like epoxy mortar. Traditionally, mastic was an organic plant-based resin from the Pistacia lentiscus shrub, and its term is related to the word masticate, due to its sticky, gummy consistency.

Pros
  • It sticks very well, so tile sag on vertical surfaces during curing is minimized

  • Unused mastic can be saved

  • When it comes time to demolish the tile, tile mastic makes it relatively easy to remove the tile

Cons
  • Mastic's quick-grab feature means that it is difficult to fix poorly aligned tiles

  • Mastic cannot be used in high-moisture areas

  • Mastic has a pronounced odor

Today, the term mastic is infrequently used, and it is difficult to find tile adhesives that go under the mastic banner at your local home center. Henry 314 Ready Set Premixed Mastic Adhesive is one of the few exceptions that actually incorporates the word mastic. For the sake of clarity, look for tile adhesives advertised as fast grabbing with no-sag qualities that are generally used for porcelain, quarry, stone, ceramic, and mosaic tile.

The best uses for tile mastic include:

  • Kitchen walls and backsplashes
  • Bathroom backsplashes
  • Bathroom walls, if not adjoining a shower or tub
  • Any walls where moisture is not prevalent
Thinset Mortar vs. Mastic vs. Epoxy Mortar Summary
Thinset Mortar Mastic Epoxy Mortar
 Moisture Factor Thinset can be used in very wet areas, even areas that will be completely submerged in water. Mastic can be used in dry or damp areas only. It cannot be used in areas that will be submerged in water, such as swimming pools. Epoxy mortar is waterproof and chemical resistant, which makes it ideal for industrial applications.  
 Best Areas Thinset can be used for showers, bathtubs, backsplashes and other areas. Walls, wainscots, dry backsplashes are key areas where tile mastic tends to be used. Epoxy mortar can be used on nearly any surface that needs a strong, waterproof hold, but its higher cost means it isn't always the best option.  
 Pros Thinset is inexpensive and it fills in gaps and depressions. Mastic is very sticky, grabs fast, and is quick setting.   Epoxy is quick-setting, meaning you can grout shortly after tiling.
 Cons Thinset is slow to set, which can lead to tile sag on vertical applications. Mastic can give off a sharp, strong odor that takes time to dissipate. Epoxy is expensive and can be difficult to use for beginners and DIYers.  
FAQ
  • Are mortar and tile adhesive the same?

    The difference between mortar and tile adhesive comes down to technicalities. Technically, mortar is a type of adhesive. The confusion comes from the fact that many people, including industry professionals and major brands, use the term "tile adhesive" to refer to tile mastic, which isn't the same thing as mortar.

  • Can I use tile adhesive instead of grout?

    Tile adhesive and grout are not the same thing and should not be used interchangeably. Tile adhesive will not wash away from tiles in the same way that grout does and, if left too long, may not wash off at all.

  • How long does tile adhesive last?

    Premixed tile adhesives have a shelf life of around six to 12 months. Powdered adhesives will typically last longer, but you should always consult the manufacturer's label to ensure you don't use tile adhesive that is expired, as the holding power and performance will likely be compromised.