Commercial Kitchen Grout: Quarry Tile, Epoxy, Furan and Washdown

Restaurant and food service kitchens are usually tiled with quarry tile or heavy porcelain and grouted with a chemical-resistant epoxy meeting ANSI A118.3. Food acids, rancid fats, degreasers and hot water washdown dissolve and wash out cement grout. Furan grout is reserved for the harshest acid and heat exposures.

Why cement grout wears out in commercial kitchens

Cement grout is built on portland cement, which is strongly alkaline. Acids neutralize and dissolve it. A commercial kitchen floor is a steady source of acids: lactic acid from dairy, acetic acid from vinegar and pickling liquids, citric acid from fruit and juices, and tomato products. Animal and vegetable fats spilled on the floor break down over time into free fatty acids. These do not destroy grout in a day, but they never stop, and each night's washdown carries away the softened surface.

Heat and water multiply the effect. Many kitchens hose or machine-scrub floors with hot water and degreaser daily. Dish areas see water at sanitizing temperatures. Tilting kettles and steam kettles can dump near-boiling water and stock across the floor. Cement grout under that regime erodes into recessed joints, then the tile edges chip, and the low joints collect debris and bacteria that no mop reaches. The progression usually starts in front of fryers, dish machines and prep sinks.

That is why the tile industry and food service designers specify chemical-resistant grout. The quarry tile grout guide covers quarry tile in general; this page focuses on the commercial kitchen environment.

Kitchen exposures and what they do to grout

Grout options for commercial kitchens

Chemical-resistant epoxy (ANSI A118.3)

ANSI A118.3 covers chemical-resistant, water-cleanable tile-setting and grouting epoxy. These products resist many acids, alkalis and cleaners and absorb almost no water. Installation is covered by ANSI A108.6. The phrase "water-cleanable" means the uncured residue can be cleaned off with water during installation; it does not mean the cured grout is weak against water.

Not all epoxy grouts are equal. Every maker publishes a chemical resistance chart rating the cured grout against specific chemicals and concentrations (for example, lactic acid, citric acid, acetic acid, sodium hydroxide and sodium hypochlorite) over set exposure periods. Commercial kitchen specifiers read that chart against the actual products used in the kitchen. Some epoxy lines are designed for industrial and food plants, with higher temperature tolerance and broader chemical resistance than residential-oriented epoxies. See epoxy grout.

Furan resin grout (ANSI A118.5)

Furan grouts are carbon-filled resin systems with very high resistance to acids and solvents, and they tolerate higher temperatures than most epoxies. They are used in dairies, breweries, meat and poultry plants and other industrial food operations where hot acid exposure is constant. Installation follows ANSI A108.8. Furan is black, has a strong odor during installation, and typically requires the tile face to be precoated with a wax that is removed after grouting, so it is a specialist job. Furan is generally weak against strong oxidizers, so chemical compatibility still has to be checked. For restaurant kitchens, a high-grade epoxy is usually sufficient. See specialty grouts.

Cement grouts

Standard (ANSI A118.6) and high-performance (ANSI A118.7) cement grouts are used in light food service areas: front-of-house, staff areas, dry storage and some low-volume kitchens. They are not the right choice for cook lines, dish areas or prep areas with constant acid and grease exposure. Sealers help cement grout resist stains briefly, but daily degreasing and washdown strip them quickly.

Quarry tile and joint layout

Quarry tile is an extruded, unglazed tile defined in ANSI A137.1. It is dense, slip resistant in its abrasive versions, and tolerant of impact, which is why it has been the commercial kitchen standard for decades. Common sizes are 6 x 6 and 8 x 8 inch, often about 1/2 inch thick. Heavy-duty unglazed porcelain is increasingly used as well.

• Joint width: Quarry tile is usually set with joints of about 1/4 inch, sometimes 3/16 to 3/8 inch, to accommodate size variation and give the grout enough mass. The wide grout joints guide covers wider joints.
• Full joint depth: Grout should fill the joint to nearly the full tile depth. Shallow grout over high thinset is the most common reason epoxy joints fail early in kitchens. See grout joint depth.
• Cove base: Sanitary cove base tile at walls, with a rounded inside corner, removes the right-angle corner where debris collects.
• Grout color: Dark reds, browns and grays match quarry tile and hide residual staining. Epoxy color is stable, so the choice is mostly aesthetic.

Slope and drains

Commercial kitchen floors are designed to drain. Floor drains, floor sinks and trench drains collect washdown water, and the floor slopes toward them, commonly 1/8 to 1/4 inch per foot depending on the design and local code. Getting slope right is a substrate job, done in the concrete or the mortar bed, not with thick thinset. Standing water in low spots keeps grout wet with food-contaminated water, which is where erosion and odors start.

Grout joints around drain bodies and trench drain frames are where different materials meet. The tile system and drain manufacturer details usually call for a chemical-resistant sealant joint at the drain frame, not grout. Movement joints in the field follow TCNA EJ171, which calls for closer spacing where tile is exposed to moisture or temperature swings than in dry interiors. In kitchens, those joints need a sealant with chemical resistance suited to the environment, often a urethane or polysulfide type specified for the use. See caulk vs grout movement joints.

Health inspection and cleanability

The FDA Food Code, which most US states and localities adopt in some form, requires floors, walls and ceilings in food service areas to be designed and constructed to be smooth, durable and easily cleanable, and in areas subject to moisture, nonabsorbent. It also calls for floor and wall junctures to be coved and closed (to no more than about 1/32 inch, or 1 mm) where floors are water-flushed for cleaning. Local health departments interpret these rules and may review finishes during plan review.

Grout is part of the floor surface for inspection purposes. Recessed, missing or porous grout joints hold food residue and bacteria and can be cited as a surface that is not easily cleanable. Epoxy-grouted tile, installed with full, flush or slightly tooled joints, is widely accepted in food service because the joint surface is nonabsorbent and does not erode under washdown. Check with the local health authority during design; requirements differ by jurisdiction.

Installation points for kitchen epoxy

1. Clean joints before grouting. Remove thinset, dust and any oil contamination. In remodels, grease in the substrate or old joints prevents bond and must be removed.
2. Control temperature. Epoxy cures slowly in cold spaces and sets fast in hot ones. Kitchens under construction are often unheated or very warm from equipment testing. Work within the TDS temperature range.
3. Pack and clean in sections. Quarry tile's texture holds epoxy residue. Work small areas, clean with the maker's recommended method, and do a final haze removal within the TDS window. See how to apply epoxy grout.
4. Keep equipment and traffic off. Light traffic is often allowed after about 24 hours and full chemical service after about 7 days at 70 deg F, but this varies. Do not start washdown with hot water and degreasers before the TDS says the grout has reached chemical resistance. See how epoxy grout cures.

Cleaning and maintenance

Epoxy-grouted kitchen floors are cleaned with the same alkaline degreasers and hot water used for the tile. Two habits matter most: rinse degreaser residue so it does not build a sticky film that attracts soil, and squeegee water to drains rather than letting it evaporate. A film that makes epoxy grout look dirty is usually residue, not stain; see cleaning epoxy grout and grease and food stains on grout.

Eroded cement grout in an operating kitchen is usually replaced with epoxy during a shutdown window. Grout removal, joint cleaning and epoxy installation in an existing kitchen require degreasing the joints thoroughly first. For the process, see regrouting tile floors, and for whether regrouting is enough, repair or replace grout.