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What Are The Best Shower Tile Adhesives?

The tile adhesive in your shower has a big job. Not only must it firmly cement the tile to the walls and floor, but it must also hold for many years without cracking, crumbling, or bowing. And it has to withstand the moisture-laden environment of the shower without mildewing or losing its grip. So, how do you choose the best one for tiling your shower among all the adhesives available?  We've done the research, and we have the answers for you! 

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The best tile adhesives in a high-moisture area such as a shower are thinset mortar and epoxy mortar. Do-it-yourselfers typically choose pre-mixed thinset mortar, while professionals generally use epoxy mortar or standard powder thinset. For tiling a shower floor, you can also use a "mortar bed." 

In the remainder of this article, we will discuss each of these materials in detail, explain why they are the best choices for shower tiling, and investigate the advantages and disadvantages. We'll also discuss other common types of adhesives, such as mastic and Type 2 adhesives, and explain whether they can be used in showers. Keep reading to learn more about shower tile adhesives!

What Are The Best Shower Tile Adhesives?

It is critical for any tiling job that you choose the best adhesive -- the most effective material for bonding to both the tile and the substrate. Although there are many adhesives on the market, selecting the right one is a relatively simple process. The area's location to be tiled (floor, wall, dry area, moist area) and the type of tile to be used (porcelain, ceramic, glass, metal, stone) determine which adhesive is best for the job.

For the shower's wet environment, only two adhesive materials are effective: thinset mortar and epoxy mortar. On shower walls, these materials are applied in a single layer over the substrate before installing tile; on the floor of a shower, they can be used either as one layer or in a multilayer "mortar bed."

Thinset Mortar

Placing tiles for the bathroom

Thinset mortar consists of Portland cement, silica sand, and one or more water retention agents. It comes in two forms: a powder activated by mixing it with water and a pre-mixed compound in a plastic tub. The powdered form is less expensive but somewhat tricky to mix accurately and is typically used by professional tilers; the pre-mixed compound costs substantially more but is more manageable for DIYers to use.  

Advantages

  • Thinset creates a strong bond with cement board substrate and with most types of tile.
  • It is highly resistant to moisture, a critical feature in shower tiling. 
  • Due to its ingredients' non-organic nature, thinset does not mildew in moist conditions such as a shower.
  • It is impervious to heat, so it will not peel away from the substrate in hot conditions.  
  • It does not expand or contract with changes in temperature or humidity.
  • Thinset can fill small gaps, chips, or holes in the substrate; it can also correct minor issues with leveling.
  • It cures relatively slowly, allowing the DIYer more time to place and adjust tiles before the mortar hardens.

Disadvantages

  • Due to the relatively long curing time of thinset mortar, tiles applied to a wall have a greater risk of sagging (sliding downward in the wet mortar).  The use of tile spacers can prevent this issue.
  • Thinset has a tendency to crack; purchasing "modified" thinset mortar, which has special additives of acrylic or other polymers, solves this problem.
  • It is not recommended for use with large, heavy tiles or tiles with uneven back surfaces due to the mortar's thinness.
  • Thinset mortar should be applied to cement backer board rather than to wood or drywall substrate; adding cement board to existing substrate adds expense to the project. 

Click here for pre-mixed thinset mortar on Amazon.

Epoxy Mortar

Epoxy mortar consists of resin, a hardening agent, and a powdered filler. These components must be mixed just before using the mortar, and the mixture hardens quickly, so it is crucial to install the tile swiftly and efficiently. For this reason, professionals use epoxy mortar much more often than DIYers do.

Advantages of Epoxy mortar

 Advantages

  • Epoxy mortar is entirely waterproof, so it doesn't need additives to keep it from cracking.
  • It forms a strong bond with multiple types of substrate and tile.
  • Epoxy mortar is resistant to discoloration and damage by most types of chemicals.
  • Its non-organic ingredients make it mildew-proof.
  • Because it cures so quickly, the entire job takes less time to complete. 

Disadvantages

  • Due to the quick (45-minute) curing time of epoxy mortar, tile must be placed quickly and accurately.
  • It must be used when the ambient temperature is between 60 and 90 degrees Fahrenheit.
  • Epoxy mortar has a strong odor during installation and while curing.  
  • It is more expensive than thinset mortar.

Disadvantages of using Epoxy mortar

Click here for epoxy mortar on Amazon.

Mortar Bed   

On the shower floor, some professionals and DIYers choose to build a "mortar bed" -- a multi-layer mortar structure strengthened by embedded wire mesh. This strategy is highly labor- and time-intensive, but it creates a strong and long-lasting bond. The bed can be "anchored" (mortar bonded directly to the substrate) or "floating" (with a thin membrane separating it from the substrate). You can use either thinset or epoxy mortar to create a mortar bed.  

Can You Use Pre-Mixed Thinset In A Shower?

Tile setter placing tile adhesive

Yes. Manufacturers highly recommend pre-mixed thinset mortar for DIYers to use on smaller projects such as showers, laundry rooms, and bathroom or kitchen backsplashes. It shares all the characteristics of standard thinset: strength, resistance to moisture and heat, and capacity to level the substrate's surface. Pre-mixed thinset can be used anywhere that standard thinset can; its higher cost is the only reason it is not commonly used on large projects. 

What Is The Difference Between Type 1 And Type 2 Tile Adhesives?

You may see some adhesives labeled "Type 1" or "Type 2," as well as others that are not labeled at all. These are not official terms, and companies decide whether or not to include one of these descriptors on the labels of their adhesive products. So, what's the difference, and how can you tell? This question is also easily answered: Type 1 adhesives are waterproof; those labeled Type 2 are not.  If an adhesive's label does not specify a Type, read the label carefully to determine whether it is, or is not, impervious to water.  

Is Mastic Okay For Shower Tiles?

mastic crystals

Mastic is a different type of tile adhesive, one which "grabs" tiles quickly and holds them tightly, eliminating sagging on vertical installations. It works with a limited array of tile materials: stone, porcelain, glass, and ceramic. Mastic is manufactured from organic materials, so it is vulnerable to mildewing and deterioration in high-moisture environments; therefore, you should not use it in showers or bathroom floors. However, you can use it for tile backsplashes in bathrooms and kitchens. 

In Closing

What Are The Best Shower Tile Adhesives?, The worker applies the glue to a tile on a concrete floor

Installing tiles in your shower can provide a sleek new look, as well as protection against water damage to your bathroom walls. It's essential to use an adhesive that bonds firmly, resists mildewing, and retains its strong hold. By selecting thinset mortar or epoxy mortar for your shower tiling job, you can be sure that its attractive new look will last for many years. 

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