It’s what’s between the tiles that counts:
Grout is forced into the spaces between tiles with a rubber tool called a float. The excess is wiped away with a wet sponge, leaving joints filled to just below the surface. After the grout cures rock-hard, the tiles are polished with a soft cloth to remove any “grout haze” left behind.
When grout does its job — locking tiles tight, keeping out water, and giving floors and walls a finished look — nobody pays much attention. It’s only when grout fails, becoming stained, cracked, or falling out altogether, that people take notice.
But grout deserves more respect. “Not only does grout fill the voids, it makes the floor, wall, or countertop stronger by bonding the tiles together and preventing the edges of a tile from chipping and cracking,” says Jay Broadwell, Owner of Grout Logic, LLC in New Orleans, LA.
Grout comes in two basic types, and the choice of which one to use depends not on the tiles but on the width of the joints between them. Narrow joints of 1/8 inch or less call for unsanded grout, a pudding-smooth blend of Portland cement and powdered pigments mixed with water. Joints wider than 1/8 inch get sanded grout — the same material, but with sand added. The sand helps bulk up the grout and keeps it from shrinking in the joints.
Older cement-based grout was brittle and prone to cracking. It also dried irregularly, leaving colors inconsistent. Today’s grouts use polymer additives, which ensure color quality and increased flexibility, allowing for joint widths of up to 1 1/4 inches. Those wide joints come in handy for camouflaging irregularities in handmade tiles and for bridging the varying thicknesses of tile in some patterned installations.
Despite their improved performance, however, all cementitious grouts are porous and subject to staining. That’s why manufacturers and installers recommend sealing grout after it has cured for a and is completely dry. Sealers come in two varieties: membrane-forming and penetrating. The first type is prone to peeling or getting cloudy when residual moisture from mastic or underlayments pushes to the surface of the tile. Penetrating sealers, which still breathe after soaking into tile and grout, are preferable.
There are some settings — notably those exposed to acids and greases — in which even an additive-enhanced, sealed grout falls short. Such harsh conditions call for epoxy grout. Made up of two parts, resin and hardener, epoxy grout comes in both sanded and unsanded varieties and is impervious to most chemicals and stains. Early epoxies were unforgiving and difficult to apply, and had just a 45-minute pot life. This made them fast to cure but slow to be embraced by many tile setters, and anathema to beginners. The new generation of epoxies contain detergents in the hardeners, which make for quick cleanup with water and improve workability. Because epoxy can discolor porous surfaces, such as unglazed quarry tiles or limestone, these should be sealed before grouting. But its stain resistance, hardness, and durability make epoxy grout the best choice for applications such as kitchen counters, backsplashes, floors, and other heavy-traffic areas.
Choosing very different tile and grout colors can provide a striking contrast.
When it comes to grout color, there are three approaches: contrasting (say, white grout with black tile), harmonizing (green grout with green tile), or neutral (a shade of gray or white).
If you do choose a bold color, have our technicians grout up a sample section of tile on plywood and live with it for a few days.
Worn and blackened, the grout on a kitchen counter and backsplash first gets a dose of powerful degreaser. “Never clean tile and grout with an oil-based soap,” Broadwell says. “The wax in them builds up and stains grout.”
Care and Repair
Years of food and grease stains can penetrate surfaces, leaving grout a dingy mess. In extreme cases, the only cure may be to regrout or retile, but more often than not old grout can be renewed. All it takes is a degreasing agent, our propriety grout neutralizer, and elbow grease. Some spot regrouting is usually necessary — a process that involves digging out and replacing cracked or crumbled areas.