No other piece of real estate has been at the center of more heated discussions than the grout joint. Color variations, grout aesthetic and joint width size (1/16 to 3/4 inch or 1 1/2 to 19 mm) all play a role in grout selection. When grout does its job — locking tiles tight, aesthetically filling the joints and giving floors and walls a finished look — nobody pays much attention to it. It is only when the grout begins to fail that the phone begins to ring off of the wall with complaints that the grout is exhibiting color shading or variations, staining, cracking, powdering or succumbing to chemical attack that can result in disintegration of the grout joint.

All grouts do the same job, but they can have individual characteristics. Some grouts are more economical, while others are designed to save time and provide ease of application. There are even some grouts that are formulated to perform in the harshest of environments and chemical exposure. How does one match the right grout to the right application? Let’s take a look at some of the “Do’s” and “Don’ts” when selecting grouts.

Standard cement-based grouts (ISO 13007 CG1WA/F and ANSI A118.6) and high-performance cement-based grouts (ISO 13007 CG2WA/F and ANSI A118.7)

Cement-based grouts can be an economical and aesthetically pleasing solution to many tile, stone and glass installations.

DO use a grout additive or grout sealer to improve stain resistance if this grout will be exposed to daily staining and cleaning regimens in kitchens and bathrooms. Because both standard and high-performance cement-based grouts (A118.6 and A118.7) are porous (typically 5 to 18% water absorption), a grout maximizer can be used in place of water to increase resistance to water, dirt and common household stains. If additional protection from staining is desired for the grout joint, as well as for the tile or stone, use a sealer once the grout is applied and ready for a sealer.

DON’T use too much water either in mixing or in the cleanup process. To minimize the potential for efflorescence* in Portland-cement-based grouts, only use the amount of water indicated on the Technical Data Sheet (TDS) or packaging. This guideline also applies during the post-installation cleanup process. Wringing out the cellulose cleanup sponge so that it remains wet, but is not dripping, will prevent it from saturating the grout joints with excess water, which could lead to efflorescence.

* Efflorescence occurs when soluble salts rise to the surface and powder out on the grout joint surface.

DON’T install grout under extreme environmental conditions. Temperature, humidity and wind can affect the way a grout cures. Cement-based grout cures best when installed and maintained between 70° and 80°F (21° and 26°C) with 50% relative humidity. Ideally, it is best to store grout and the mixing water at this temperature for 24 hours before the installation. Pulling the grout from the back of a truck or a van that has been baking in the sun, without acclimating it, could cause problems not only with the installation, but with the grout results as well.

Epoxy or reaction resin grouts (ISO 13007 RG and ANSI A118.3)

Epoxy grouts will always outperform even a high-performance cement-based grout (ISO 13007 CG2WA/F and ANSI A118.7) due to the low porosity (0.4%), resistance to chemicals/stains and rigorous cleaning regimens.

DO use an industrial-grade epoxy grout when harsh conditions are specified — such as industrial, commercial and institutional wall and floor installations. An industrial epoxy grout that provides high chemical and heat resistance, while being able to withstand even the most rigorous cleaning regimens, is perfect in commercial kitchens exposed to oleic fatty acids, heat and enzymatic cleaners.

DON’T expect all epoxies to perform the same. Each epoxy is formulated to handle specific chemicals, cleaners and service duty. For applications ranging from residential to heavy industrial, it is critical to match the right epoxy to the right application. Always consult the manufacturer’s technical data sheet to determine suitability for the specified installation and chemical exposure.

Premixed grouts or mastics (no standards exist)

DO use these grouts in drier conditions with very limited water (RES 1 or COM 1), such as backsplashes and tub surrounds. Shower floors may be acceptable by some manufacturers for residential applications.

DON’T use in wet areas unless otherwise directed by the premixed grout manufacturer. Mastic will break down in the joint and emulsify.


To ensure a beautiful tile application, it is important to consider the type of environment to determine the appropriate grout for the installation.

An industrial-grade epoxy grout is a necessity when it comes to industrial, commercial and institutional wall and floor tile installations.

An epoxy grout formulated to provide high chemical and heat resistance, while being able to withstand rigorous cleaning regimens, is ideal for tile applications in commercial kitchens.

The latest in coated-quartz (CQ) technology, used in products such as Mapei’s Flexcolor CQ grout, ensures color consistency with no color bleed in rise water and no re-transfer of color to the tile surface.

The Tile Council of North America (TCNA) environmental exposure classifications

(Refer to the most current TCNA Handbook for a detailed explanation of these classifications.)

  • Res 1 (Residential Dry) — not exposed to moisture or liquid, except when cleaning; e.g. living rooms
  • Res 2 (Residential Limited Water Exposure) — subject to moisture or liquid, but not soaked; i.e. bathroom floors
  • Res 3 (Residential Wet Areas) — subject to moisture or liquid, often soaked; e.g. shower walls and floors
  • Res 4 (Residential High Humidity, Heavy Moisture Exposure) — subject to continuous high humidity plus heat and moisture, with intermittent use; e.g. combination steam shower
  • Res 5 (Residential High Temperature Air/Water> 125 degrees F
  • (52 degrees C) — subject to water and/or vapor of 125 degrees F
  • (52 degrees C); e.g. furnace areas
  • Res 6 (Residential Exterior) — subject to exterior conditions; e.g. balconies
  • Res 7 (Residential) — for submerged conditions; e.g. residential pools

 

  • Com 1 (Commercial Dry) — not exposed to moisture or liquid, except when cleaning; e.g. interior rooms
  • Com 2 (Commercial Limited Water Exposure) — subject to moisture or liquid, but not soaked; e.g. bathroom floors
  • Com 3 (Commercial Wet Areas) — subject to moisture or liquid, often soaked; e.g. shower walls and floors, not gang showers
  • Com 4 (Commercial High Humidity, Heavy Moisture Exposure) — subject to continuous high humidity plus heat and moisture, with continuous use; e.g. public steam showers, including gang showers
  • Com 5 (Commercial High-Temperature Air/Water> 125 degrees F) — subject to water and/or vapor of 125 degrees F (52 degrees C); e.g. saunas
  • Com 6 (Commercial Exterior) — subject to exterior conditions;
  • e.g. commercial facades
  • Com 7 (Commercial) — for submerged conditions; e.g. public pools

 

*Note: Commercial designations, Com 1-6, will always have a greater exposure to water, moisture and heat — both in increased levels and duration time. This increased exposure also includes more rigorous cleaning regimens in a commercial or industrial environment that are performed on a continuous basis.