A Guide to Selecting the Proper Adhesive and Grout

By Arthur Mintie, LATICRETE Senior Director of Technical Services

Laticrete - BIOGREEN InstallWith today’s industry standards requiring various product performance levels to be matched based on specification demands, local codes and complexities, selecting the proper adhesive and grout isn’t always a walk in the park. Usually, the more demanding the application, such as areas heavily exposed to the outdoors, require the most intensive adhesives, grouts and installation accessories. These types of applications require the installation products to have better working properties and ultimately better performance properties and characteristics such as higher bond strengths, flexibility and weather resistance.

Here are a few considerations to match the right adhesive and grout for the project.

Where is the Installation Taking Place?

Selecting a grout and adhesive that will withstand time, wear and environmental elements has been a challenge confronted by installers, designers and builders for decades. For example, an internal wall application may require a pre-mixed adhesive or a powder-based adhesive depending on the type of tile used, such as small ceramic tiles or 10’ by 5’ (3 meter by 11/2 meter) gauged porcelain tile panels.

If the project at hand includes bathroom walls, backsplashes or vanities, choosing a pre-mixed adhesive would be ideal. Pre-mixed adhesives tend to be easier to work with in most vertical cases – just pop the lid and go.

When working with shower installations, floor tile or large gauged thin porcelain tiles and panels, cement-based, powder-based adhesives are easier to work with because the installation contractor must mix the material before application. The contractor is in complete control and can easily manipulate the material if needed to create a specific mortar consistency for the targeted installation.

Grouts also vary depending on the application area and come in pre-mixed, cement-based powder types and epoxy-based formulations as well. Epoxy and high-performance cement-based grouts are best suited for wet areas as they are intended to be mildew-resistant and known for retaining their color well. Epoxy grout is the most common choice for countertops due to its consistency. The material tends to be harder, is chemical and stain resistant and does not need to be sealed, saving contractors an extra step.

What Types of Tiles are Being Used?

Tile design has a significant impact on the adhesives and grouts that can be used for installation. For example, when it comes to installing large and heavy tile, a thicker adhesive bond coat is required to achieve proper coverage and eliminate voids under the tile while minimizing slumping of the tile. Specially designed large and heavy tile mortars (LHT types) are ideal for these applications. If the installation is vertical, this will require an adhesive with outstanding non-sag properties. In contrast, gauged porcelain tile panels that are half the thickness and weight of conventional tile, but often very large in size, need a high-performance adhesive that offers an extended open time, high bond strength, excellent workability and proper curing parameters.

A Guide to Selecting the Proper Adhesive and GroutSmooth-textured (unsanded) grout is preferred in ceramic tile and stone installations with narrow joints. This type of grout clings firmly to vertical surfaces, making it easy to work with and is recommended for narrow grout joints that are 1/8” (3 mm) or less. Unsanded grout is also a good choice for highly polished stones such as marble that sanded grout may scratch.

Sanded grouts are the best choice for tile joints that are wider than 1/8” (3 mm), typically up to about 5/8” (16 mm). This type of grout helps to eliminate cracks from shrinkage and has a coarser texture to provide strength.

What is the Substrate?

For plaster, plasterboard and cement board substrates, both ready-to-use adhesives and powder-based adhesives are acceptable. For exterior glue plywood, concrete or cement screed substrates, installers should use powder-based products.

Factors that affect the choice of adhesive for a specific application include the quality of the substrate, the application process, such as cure time and volume used, and the environment in which the installation takes place, such as high humidity or cold temperatures.

Grout choice is also susceptible to these factors. In exterior environments where the installation is exposed to temperature extremes and potentially cold temperatures, contractors should choose a high performance polymer-modified grout that has low water absorption and other performance characteristics such as freeze/thaw resistance, high compressive strength and flexibility. These high-performance grouts also have features that help the grout to resist efflorescence and cracking.

Consult the Manufacturer

With all the variables and options for tile and stone in the modern building society such as finishes, applications and accelerated construction schedules, installers should consult the specified product manufacturers or the products they wish to use prior to installation. This step will easily save installers headaches down the road when costly repairs may ensue from improper choices.

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