To paraphrase Rodney Dangerfield, grout gets no respect. Grout can ruin an otherwise great tile job. And yet grout and proper grouting technique are often treated as an afterthought, like the final few half-hearted steps of a tired runner stumbling over the finish line. Grout deserves better. Your tile deserves better.
The keys to a professional-quality grout job aren't secrets shrouded in mystery. On these pages, we'll show you some tips and techniques that will help your next grout job go more smoothly and give your tile a professional-grade finished look.
Start by vacuuming out all that remodeling dust, debris and any chips of dried thin-set from grout joints (Photo 1). If there are high spots where thin-set has oozed out and dried, use a sturdy-edged tool to scrape it out and then vacuum again, including the tile surfaces. The last thing you want is to push all that muck back into the joint as you are floating your grout in.
Tip: Tape Off the Tile Before Grouting
For easier cleanup, tape off painted walls to protect them from grout. Also tape off trim or inset tiles that feature imprinted patterns with crevices (Photo 9).
Pour some grout out of the bag into a mixing bucket. Pour water in a little at a time and start mixing by hand using a margin trowel (See “A Tiler’s Best Friend” below). Tip the bucket toward you and roll it in a “cement mixer” style as you mix (Photo 3). Be sure to scrape any dry, unmixed grout from the bottom of the bucket with your margin trowel. Keep mixing until all the powder has been absorbed and it has the consistency of peanut butter. When you're getting close, dribble in water from a sponge. It only takes a little too much to create soup. And don't mix grout with a drill and mixing paddle. This method churns the grout and introduces air into the mix. That weakens the cured strength and causes a type of discoloration called “shading.” Besides, we're trying to mix grout here, not make soufflé.
Let the grout “slake”
When your grout has reached peanut butter status, stop! Go and make a sandwich, take out the trash, whatever. Let the grout slake (rest) for about 10 minutes. This allows the chemicals in the grout to work their magic. Skipping this step may result in weaker, crack-prone joints. After slaking, the grout will feel a bit stiffer, but don't add more water. Remix the grout by hand again to loosen it up.
A Tiler's Best Friend
Buy yourself a margin trowel for 10 bucks. You'll use it for mixing grout and thin-set, scraping out joints, cleaning buckets and tools, spreading mayonnaise, flipping pancakes....
You're now ready to grout. Tip the bucket toward you (like you did when mixing) and “drag” some grout with your float up the side of the bucket toward you. This pulls a “working batch” closer to you and makes it easier to scrape up a decent amount of grout onto your float. Push the float tight against the side of the bucket and scrape off a dollop of grout (Photo 4). Any excess that falls off will only fall into the bucket and not off the edge and onto the floor.
Always grout the walls first, and after they're finished, the floor. That’ll keep you from messing up a finished floor. Apply the grout diagonally across the tile joints to squish the grout into the joints (Photo 5). Use whichever side or corner of the float is necessary to fully compress grout into the entire joint. On vertical surfaces, apply grout upward. That way you won't drop so much on the floor.
After you've filled all the joints, make your first “cleanup” passes with the float. Your goal is merely to get as much excess grout as possible off the face of the tile. Hold the float at a sharp angle to the tile and scrape excess grout from the surface. Use a serpentine motion to make it faster and easier (Photo 6).
Once the grout has started to harden (20 to 30 minutes), begin sponging (Photo 7). Don't use just any sponge, especially one from the kitchen; choose a “hydrophilic” (water-loving) sponge. They're sold near the tile supplies. Make sure it's damp, not wet, and sweep diagonally across the face of the tile and wipe the grout off the tile surface. On your first few passes, the grout will smear all over the tile and look like a mess—that's OK. Just rinse out your sponge often in a bucket of clean water (never in the sink) and keep wiping until most of the smeared-on grout is gone.
When the surface has been cleaned, begin “tooling” (smoothing and leveling) the grout lines with the sponge. Hold the sponge in your palm and, gently pressing down with your index finger, run the sponge over any grout joints that look too high or uneven (Photo 8). The goal is consistent, even-depth grout joints. Don't push too hard; let the sponge do the work.
After all the joints have been dressed, step away for about a half hour to let the surface dry and form a haze. Then wipe away the haze with a towel. Regular towels work, but microfiber towels are the hot ticket for this task. With more fibers, they remove grout haze much quicker and cleaner than a regular towel.
Don't grout inside corners. Inside corners that are grouted will always crack over time. Choose a matching color caulk designed to coordinate with the grout you've used. It's sold in matching colors near the grout.
Sanded vs Unsanded Grout
Sanded grout is stronger than unsanded grout and resists shrinkage and cracking better. As a rule of thumb, sanded grout should be used in joints larger than 1/8 in. Realistically, as long as you can force the grout into the joint, use sanded grout. But on soft stone tiles like polished limestone or marble, use only unsanded grout or you'll scratch the surface.