All About Grout

By: Jefferson Kolle, This Old House magazine (Page 2 of 5)

Photo: John Lawton

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.

Photo: John Lawton

Epoxy grout is more expensive and more difficult to apply, but its durability makes it a good choice for high-traffic areas.

Photo: John Lawton

Choosing very different tile and grout colors can provide a striking contrast.

Photo: John Lawton

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," Parker says. "The wax in them builds up and stains grout."

Photo: John Lawton

A steam cleaner brings stains to the surface, where Parker and Thorp wipe them up. Homeowners can rent steam machines, but a stiff-bristle nylon brush and a degreaser also do the trick.

Photo: John Lawton

To remove failed grout, Parker uses a utility knife on thin, unsanded joints and a diamond-encrusted grout saw on sanded joints. "Just skimming over the old grout with new doesn't work," she says. "You have to remove at least half the depth of the old stuff before the new will bond to it."

Photo: John Lawton

The next step is to regrout the missing areas. Parker mixes up a batch and spreads it with a float. Most old grout is white, which makes color-matching relatively easy. In high-moisture areas, such as around faucets, and wherever tile abuts a dissimilar material, caulk is needed to keep out water.

Photo: John Lawton

When the grout has cured for several days, Parker returns to brush a penetrating sealer on the joints. "People are amazed after we've finished a job," she says. "One guy thought we had completely retiled his bathroom."

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Epoxy Grout

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. Epoxy grout is expensive — as much as $8 per pound, compared with $1 to $2 for cement-based grout — but there is an upside to the cost differential: Powdered Portland cement grouts have a shelf life of only one year, while two-part liquid epoxies, if they are not subjected to freezing temperatures, will last forever in their sealed containers.