Grouting Tips and Techniques

Step 1: Prep work - Start with clean joints

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Photo 1: Clean the joints

Vacuum the grout lines, then scrape any protruding grout and vacuum again. Don't scrape too hard or you may chip the tile glazing.

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Apply tape to trim tiles

Photo 2: Tape off edges and trim tiles

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.

Step 2: Mix the grout by hand

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Photo 3: Mix the grout until it's powder-free

Mix the grout with a margin trowel until all the powder is dissolved. Roll the bucket frequently while mixing. Scrape the bottom to make sure all the grout is mixed.

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.

Margin trowel

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....

Mix grout to peanut butter thickness

As Thick as What?

Mix your grout to the consistency of creamy peanut butter.

Step 3: Load the grout float

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Photo 4: Load the grout float

Tip the bucket toward you. Drag some grout “up the slope,” then scoop it onto the float.

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.

Step 4: Load the joints

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Photo 5: Spread the grout

Smear the grout diagonally across the tile to force it deep into the joints and prevent it from being sucked back out as your float slides along.

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.

Step 5: Clean off excess grout

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Photo 6: Squeegee off the excess

Remove the bulk of the grout by wiping in a serpentine motion. This helps evenly distribute the grout and prevents the grout float edge from digging into grout lines.

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).

Step 6: Sponge the surface

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Photo 7: Sponge off the surface

Sweep a damp (not wet!) sponge diagonally across the tile. Rinse your sponge often and repeat until you’re left with a thin haze.

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.

Step 7: Tool the grout lines

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Photo 8: Tool the lines

Depress the sponge with your index finger and smooth out high or uneven grout lines. Don't push too hard. Your goal is grout joints all the same shape and depth.

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.

Step 8: Towel off the haze

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Photo 9: Buff out the haze

After the grout film has dried, polish away the haze with a cotton towel or, better yet, a microfiber towel.

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.

Store extra grout in a plastic bag.

Tip: Keep Some Grout for Repairs

It's a good idea to hold on to a small quantity of unused grout for future touch-ups. Grout will easily absorb ambient moisture, so store it in an airtight container such as a resealable plastic bag or a canning jar.

Step 9: Caulk all inside corners

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Photo 10: Caulk inside corners

Don't grout inside corners. Use a grouting caulk on inside corners after grouting and cleaning. Don't overfill the void; you'll just make it harder to tool and clean.

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.