When it comes to tiling commercial kitchens, everyone familiar with these projects agrees that the installation is facing a harsh environment. The substrate, waterproofing products, mortar, grout and tile are under constant attack by varying temperatures, boiling grease, bacteria, harsh chemicals, acidic cleaning techniques and the abundant use of water.
Quarry tile makes an excellent finish choice for commercial kitchen floors due to it meeting Class IV requirements of ANSI A137.1 (heavier amounts of traffic with greater amounts of dirt and/or other abrasives present). This excellent quality tile floor will not last long unless careful attention is given to the use of properly selected, chemically resistant, setting materials. Quarry tile is unglazed, which increases the slip resistance, making it an excellent choice for areas subject to spills and excessive moisture, such as commercial kitchens. Quarry tile production has a history in the brick manufacturing industry and contains many raw materials very similar to that used in the manufacturing of brick. These hard-fired, low-absorption, commercial tiles are high quality and considered to be very durable. They are hard fired in kilns at temperatures exceeding 2,000 degrees Fahrenheit. For slip resistance, the Tile Council of North America (TCNA) recommends that tile have a Dynamic Coefficent of Friction (DCOF) greater than 0.42 for wet tile surfaces. The DCOF AcuTest® measures dynamic friction, which is the frictional resistance one pushes against when already in motion. Quarry tile is also commonly manufactured and available in treaded and abrasive textures ideal for slippery wet areas.
The TCNA Handbook for Ceramic, Glass and Stone Tile Installation is an excellent resource when specifying a commercial kitchen project. When reviewing the “Floor Tiling Installation Guide” in the front of the Handbook, you will see commercial kitchens are considered a “Heavy” service rating with the only approved substrate, concrete. The section on “Environmental Exposure Classifications” lists the commercial kitchen as a “Comm3” (Commercial Wet). The Environmental Exposure Classifications recommendation addresses heat exposure of a tile installation in addition to moisture. Kitchens are subject to an excessive amount of water typically in the dishwashing area, also common in the kitchen itself because these floors are often cleaned by hosing them down. The TCNA Handbook also lists methods of installations, with a few suitable for commercial kitchen tile installations like F113 for direct bond to a concrete substrate and F111 or F112 for bonded and unbonded mortar beds. The mortar bed method provides a great bondable surface, and the integrity of the substrate is within the installer’s control — allowing for floor flattening, leveling or contouring of the finished floor height. One issue often affecting the selection of a mortar bed is the concrete slab, which should be recessed so the finished flooring is in alignment with thresholds and rooms adjoining the kitchen. Whether the substrate is a mortar bed or direct bond to concrete, both should be sloped to drain in the wet areas.
Because of the excessive amount of moisture common in the commercial kitchen, there are a few important considerations such as waterproofing, wall protection and slip resistance of the tile. Usually, in any area where excessive moisture/water is present there should be serious consideration for waterproofing of the concrete substrate of a minimum of 4 to 6 inches up the wall. A wise consideration is to waterproof both the floor and walls. With excessive water, often the result of kitchens being hosed down in the cleaning process and the dishwashing area, a quality wall construction with a water-resistant substrate like concrete, a mortar bed or backer board is essential and waterproofing should be part of the design. The durability, cleanability and low maintenance of wall tile should be one of the driving decision makers.
Substrate preparation of the floors is the foundation of the installation. The TCNA and ANSI standards both state, “Maximum allowable variation is 1/4-inch in 10 feet from the required plane, with no more than 1/16-inch variation in 12 inches when measured from the high points of the surface. The requirement for flatness often makes the selection of a self-leveling underlayment a good choice in areas not requiring a slope.
The installation of the tile is next. A mortar meeting ANSI A118.4 should be considered the minimum standard. Due to the aggressive nature of the chemicals in most commercial kitchens, it is best to install the tile using a 100%-solids epoxy mortar.
For sanitary reasons, the tile in a commercial kitchen needs to be grouted. While in recent years grout joints have become narrow, quarry tile in kitchens is commonly 1/4-inch wide. Cementitious-based grout will degrade or deteriorate when subject to the acidic and harsh chemicals of a commercial kitchen. The best choice for grout in commercial kitchens — subjected to hot water and pressure cleaning, harsh cleaners, disinfecting chemicals, fatty acids and no rinse cleaners — is a high-performance 100%-solids, industrial-grade epoxy grout meeting or exceeding ANSI A118.3 requirements.
No commercial tile installation is complete without properly installed expansion or movement joints. The movement joints should be installed following the requirements of TCNA method EJ171. The EJ171 method requires that in areas exposed to moisture, such as a commercial kitchen, movement joints should be placed 8 to 12 feet in each direction, around any protrusions through the floor and at the perimeter. It calls for quarry and paver tile joints to be the same as the grout, but not less than 1/4-inch wide. Quarry tile is as small as it will ever be when it first comes out of the kiln. Tiles can expand as they are subject to moisture, and they age, adding to the need for movement joints. These movement joints should be finished with a high-performance sealant.
Kitchens frequently use industrial-strength cleaning products, which are considered “no rinse.” These no rinse cleaners create a film on the tile and grout that breaks down fat and proteins into a fatty acid. This acid is known to cause damage to some tile and the grout. Either remove or rinse the fatty acid or change to a neutral cleaner that is known to effectively clean quarry tile. Neutral cleaners are highly concentrated and formulated for continuous use. When used regularly and following the directions on the container, this biodegradable, neutral cleaner helps to maintain the ceramic tile as well as grout and will not cause damage to either.
When designing a demanding commercial kitchen subject to harsh chemicals, consider high heat, heavy traffic and a lot of moisture. Specify quality tile, the correct setting materials and grouts, and select a qualified tile installer familiar with the industry standards and the demands of a commercial kitchen. Also, consider the kitchen design a complete assembly if one component from the tile, installation materials or cleaning method is not designed properly from the beginning, which can cause the installation to fail — leading to costly down time and unnecessary expenses.