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Thinset, Grout & Adhesive Buying Guide

Taking on a tile project can be quite an endeavor but with big rewards. When it comes time to lay the tile, you will be faced with choosing what type of adhesive or mortar to use. With all the different types of setting materials on the market today, choosing the appropriate setting material for your project can become overwhelming. To further complicate matters, a variety of synonymous names may be used when referring to the same type of product. This guide will help you to understand the different types of thinsets, adhesives, and grout commonly available on the market today.


One of the most common and preferred setting materials for tile is thinset mortar. Also referred to as thinset, mud, mortar, and other names, thinset is a cement-based adhesive, or bonding mortar, that is used to adhere tile to the substrate. It is a mixture of portland cement, fine sand, and a water retention compound. There are both modified and unmodified thinsets available.

Thinset comes in a dry, powder form that must be mixed with water before using. For the proper results, the water must be mixed with the thinset, allowed to slake, and mixed again before using. Slaking refers to allowing the water to permeate the thinset for a specific amount of time so that the chemicals can interact and become workable. While there are some thinsets sold premixed in buckets, these are not actually thinsets but rather mastic with sand. Always follow the manufacturer’s instructions for mixing thinsets.

Modified Thinset

When a latex additive or other polymer bonding agent is added to a thinset, it becomes a modified thinset. These additive polymers may be in a powdered or liquid form. The powdered thinset may already have the polymers added and just needs to be mixed with water, or the additives may be added manually, such as mixing the thinset with a liquid latex additive instead of water.

Adding a latex additive or other polymer agent will help the thinset mix retain water for more durability, better flexibility, and increased bonding power. Flexibility is important for allowing the tile or stone the ability to move and fluctuate through the seasons. Specialty polymer agents can also add particular properties to the thinset mix to meet specific installation requirements. Premium modified thinsets will have a higher polymer ratio and be stronger but will also be more expensive.

Modified thinsets can be used in most applications and installations. Unlike unmodified thinsets that cure through only a chemical process, however, modified thinsets cure through a chemical process and a drying process. Because of this, there are certain circumstances where a modified thinset should not be used. For example, with Schluter-DITRA installations, modified thinsets are not recommended. When a modified thinset is between two impervious materials such Schluter-DITRA and ceramic tile, it can take weeks for a modified thinset to fully dry.

Sanded, Non-Sanded & Epoxy Grout

Grout is the mortar that fills the joint spaces between floor and wall tiles, brick, and other masonry work. Grouting is performed after the tile has been laid with thinset or mastic and is the final step for locking the tile into place. Grout is available in a wide variety colors and can be mixed with other additives to achieve better stain resistance, increased strength, or other properties.

Choosing the best type of grout for your installation will depend on the style and color of the tile, the size of the joint spaces, and where the tile installation is located. There are both cement-based grouts and epoxy grouts. The cement-based grouts are available as sanded and non-sanded.

Non-Sanded Grout

Non-Sanded Grout is a cement-based grout that does not contain any sand. It is typically used for smaller tile joints that are 1/16th to 1/8th inch wide. It should not be used for larger joints because as the grout cures, it shrinks. With wider joints, more grout is need to fill the space, but the more grout that is used, the more shrinkage that occurs. In wide joints, the grout can crack due to the lack of bonding strength or can even pull away from the tile if the joint is large enough.

Non-sanded grout is often used with ceramic tile, glass tile, polished marble, and other easily scratched materials because it will not scratch the surface like sanded grout might. When using these types of materials with larger grout joints, an epoxy grout is often a better choice. Because non-sanded grout tends to be stickier than sanded grout, it works well for vertical applications such as shower walls. It is also easier on the hands than sanded grout.

Available in either dry powdered form or premixed, non-sanded grout is applied with a grout float and sponge. Once fully cured, non-sanded grout becomes very hard like concrete. The grout, however, is still very porous and should be sealed with a good quality penetrating sealer to help prevent stains and dirt from entering into the pores of the grout.

Sanded Grout

Sanded grout is the most common type of cement-based grout. As the name suggests, sanded grout has fine grains of sand added to it. The addition of the sand helps prevent the grout from shrinking too much as it cures, allowing it to be used for grout joints that are larger than 1/8th inch wide. Additionally, many sanded grouts will also have a mixture of polymers already added for increased strength and flexibility.

While sanded grout is used for wider grout joints, it can become problematic for certain materials including polished marble, travertine, and other polished stone. The sand in the grout can scratch polished surfaces as the grout is wiped over the material during the grouting process. For these situations, an epoxy grout is often the best way to go.

Epoxy Grout

Epoxy grout has increasingly become more popular among tile installers and contractors. Unlike typical cement-based grout, epoxy grout is a two-part system composed of an epoxy resin and hardener. Without the addition of water, the two components are mixed together to form the epoxy grout. In some cases, such as with Laticrete SpectraLOCK, a third, color powder component, is also added to the epoxy grout mix.

Epoxy grout offers several advantages over cement-based grouts. Once cured, epoxy grout is extremely hard and durable, and because the epoxy is non-porous, it offers superior stain and water resistance. The high stain, chemical, and water resistance properties make epoxy grout easy to clean and an excellent choice for bathrooms, showers, kitchens, commercial applications, and anywhere that is prone to stains, mildew, mold, and contact with water. Additionally, the non-porous nature of epoxy grout means that a penetrating sealer is not required for stain resistance. Most premium epoxy grouts will also offer consistent color.

While there many advantages to using epoxy grout over cement-based grout, there are also some disadvantages. Typically, epoxy grout is more difficult to work with than traditional grout. It has a faster cure time, tends to be stickier, and can be harder to work into the grout joints. There may also be sag in vertical installations. Epoxy grout can also have a plastic appearance that may not be ascetically pleasing to everyone.

Tile Adhesives & Mastic

Mastic is an organic adhesive that comes from the resin of the mastic tree. The resin is very sticky and used in construction, commercial applications, and tile installations as a bonding agent or adhesive. It is available as a thin-liquid, glue, or sticky paste and comes in a pail, tube, or tube similar to caulk.

Using mastic has its advantages and disadvantages over thinset. Unlike thinset, mastic comes premixed and ready to use straight out of the pail, making it a time-saver when laying tile. It tends to be stickier and set more quickly than thinset, making it ideal for vertical surfaces where you would want the tile to stay in place immediately, such as a kitchen backsplash.

While mastic is easy to use and has a high bond strength, it also has several drawbacks. Because mastic can react with water and re-emulsify, it is not appropriate for areas that have more than limited contact with water. If the mastic begins to re-emulsify, the tile can start to lose adhesion and eventually fall from the wall. This can become problematic in shower and tub surrounds even if there is not constant contact with water. Tile not sealed properly, or a crack in the grout, can allow moisture to penetrate to the mastic. Additionally, because mastic has organic components, it can be more prone to harboring mold if there is moisture present.

Another drawback to using mastic is that it will not provide much structural support. The surface must be completely level in order to prevent "tile lippage" from occurring. Mastic cannot be built up to level off minor imperfections in a floor like thinset can, and in general, most floor applications should be done with thinset and not an adhesive.