Grout for Quarry Tile: Joint Width, Epoxy, Furan and Sealing

Quarry tile is usually grouted with 1/4 to 3/8 inch joints using sanded cement grout in homes and light commercial use, and epoxy (ANSI A118.3) or furan (ANSI A118.5) where grease, acids, hot water and heavy washdowns are routine. Unglazed quarry tile should get a grout release first, and cement grout should be sealed after cure.

What quarry tile is and why its grout is different

Quarry tile is not cut from a quarry. It is a dense red, brown or gray clay tile formed by extrusion, cut to size and fired. ANSI A137.1 classifies it separately from pressed floor tile. Common sizes are 6x6 and 8x8 inches, sometimes 4x8 or 12x12, and thicknesses around 1/2 inch, with heavier 3/4 inch tile made for industrial floors. Most quarry tile is unglazed with color through the body, and many have abrasive grit or textured faces for slip resistance.

Several features make grouting quarry tile its own topic:

• Size variation and warpage. Extruded tile varies more than rectified porcelain, so joints must be wider to absorb it. ANSI A108.02 requires the joint to be at least three times the actual size variation.
• Thickness. A 1/2 inch tile makes a deep joint. Grout volume per square foot is several times what a thin wall tile uses, which matters for ordering. The grout calculator accounts for depth.
• Unglazed, textured face. Grout residue and pigment lodge in the surface texture. Epoxy residue is especially hard to remove once it starts to set.
• Where it goes. Commercial kitchens, breweries, dairies, loading areas and rustic residential floors. The grout often has to survive more than the tile does.

Joint width for quarry tile

A 1/4 inch joint is the most common width for 6x6 and 8x8 inch quarry tile. Tile with more variation, larger formats or heavy industrial grades are often set at 3/8 inch. Some installations use 1/8 inch for highly consistent tile in residential settings, but that is the exception. Wide joints are not a weakness here; they suit the material and the grouts used with it. The wide grout joints page covers maximum widths and grout limits.

Sanded, epoxy or furan

Sanded cement grout

For residential quarry floors and light commercial areas without harsh chemicals, sanded grout is the standard choice. The sand controls shrinkage in deep, wide joints, and the color range includes the reds, browns and charcoals that suit quarry tile. High-performance cement grout (ANSI A118.7) is a step up in density and color consistency for the same uses. Cement grout is attacked by acids (vinegar, citrus, wine, some cleaners) and by the fats and sugars found in commercial kitchens, which is why it rarely lasts in restaurant work.

Epoxy grout

Epoxy grout meeting ANSI A118.3 resists grease, many food acids and frequent washing, and it does not need sealing. It is the default for food service floors. Installers working in heavy commercial kitchens often choose industrial epoxy grades with higher temperature and chemical resistance, because hot water washdowns and boiling spills can soften some standard epoxies. Check the TDS for temperature limits and chemical resistance charts. The commercial requirements are explored in commercial kitchen grout.

Furan grout

Furan grouts, covered by ANSI A118.5 with installation per ANSI A108.8, are made from furfuryl alcohol resins and cure to a black, highly chemical-resistant joint. They resist a wide range of acids, alkalis and solvents and tolerate higher temperatures than most epoxies, which is why they show up in dairies, meat plants, breweries and chemical areas. Furan cannot be cleaned off an unprotected tile face, so the tile must be coated with a temporary paraffin wax beforehand (often factory pre-waxed), and the wax is removed with steam or hot water after the grout cures. Furan installation involves acid catalysts and is done by specialists. More on these materials is in specialty grouts.

Grout release on unglazed quarry tile

A grout release is a temporary coating applied to the tile face before grouting. It keeps grout from bonding to the surface or staining the pores, then washes off or wears away. On unglazed quarry tile it is particularly helpful for:

• Epoxy grout, whose residue bonds firmly to rough unglazed surfaces.
• Dark or contrasting cement grout on lighter tile, which can stain the face.
• Textured or abrasive-grit tile, where residue hides in the texture.

Release products range from water-based liquid releases to wax coatings. Apply with a sprayer, pad or brush to the tile face only, keeping it out of the joints so the grout can still bond to the tile edges. Let it dry per the label before grouting. Some penetrating sealers are labeled for use as a pre-grout release; others interfere with grout bond, so only use a sealer that the maker approves for that purpose.

Installation notes for deep, wide joints

• Clear the joints. With 1/2 inch tile, thinset squeezes up into joints. Remove it while soft so the grout reaches at least two thirds of the tile depth; shallow grout over thinset breaks out under traffic. The grout joint depth page explains why.
• Pack, do not bridge. Wide joints take a lot of grout. Work the float diagonally and repeat passes to compact the grout fully; a quick pass can leave voids beneath the surface.
• Dampen dry, absorbent tile if the TDS allows. Some quarry tile draws water out of cement grout quickly, especially in warm rooms. A light dampening of the tile edges (no standing water) helps cement grout cure properly. Epoxy needs dry joints.
• Movement joints. Large commercial floors with thermal swings from washdowns need movement joints per TCNA EJ171, filled with a sealant suited to the chemical exposure. Grout in place of movement joints cracks and lets water into the setting bed.
• Slope and drainage. In commercial kitchens, the floor should slope to drains. Standing water on grout accelerates attack from fats and cleaners regardless of grout type.

Sealing quarry tile and grout

Whether to seal depends on the grout type and the setting.

Avoid topical film-forming sealers or waxes on floors that get wet, because they can make the floor slippery and wear unevenly. For the basics on whether sealing is necessary, see do you need to seal grout; does epoxy grout need sealing covers the epoxy question.