How to Choose the Correct Tile Adhesive or Mortar

Whether you use wall or floor tile, that tile needs to thoroughly stick to its base surface. The demands on tile adhesive are extensive and steep.

Tile adhesive is expected to hold the tile in place not just for years but for decades—without fail. 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.

Fortunately, tile adhesives have evolved to the point where all of those demands can be successfully handled. Choosing the right tile 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.

Thinset Tile Mortar

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

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 do-it-yourselfers.

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 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 does not need any special latex additives, as does some thinset.

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

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.

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.

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