How to Regrout Ceramic Tile

Grind Away the Old Grout

Fit an oscillating tool with a blade designed for grout removal. Most manufacturers sell blades designed for this purpose—usually, these are blades impregnated with fine diamond chips that make quick work of pulverizing hardened grout.

Turn on the tool and move the blade along the grout joints, holding the blade perpendicular to the tile surface. Work patiently, and take care not to allow the blade to nick or chip the ceramic tile. On the first pass, your goal is to simply remove the bulk of the grout—don't worry about removing every bit of grout on the first pass. 

As you work, pause frequently to remove dust and debris with a shop vacuum.

Clean the Grout Lines

Once you have removed most of the grout, make another pass with the oscillating tool to clean up the grout lines. This time, angle the blade slightly in order to get close to the edges of the tile. Make sure not to linger on the edges of the grout lines, as this can easily damage the tiles.

The grout should crumble quickly under the action of the blade. Do not force the blade if you find that some areas do not easily grind out—these bits of grout will be removed manually later. Vacuum the grout lines as you go.

Remove Remaining Grout Manually

Where the power tool fails to remove all traces of grout, follow up with a carbide-tipped grout removal tool or utility knife (it's fine to use a dull blade) to carve out any remaining bits of grout. Take care not to scratch the faces of the tiles.

Vacuum Thoroughly

Once the old grout has been removed from the seams, use a shop vacuum to thoroughly clear out any dust and debris. The grout lines must be completely clean and dry before filling them with fresh grout. 

Mix the Grout

Tile grout is available both as a dry powder that must be mixed with water or as a premixed semi-liquid paste in tubs of various sizes. In general, unsanded grouts are used for grout joints 1/4 inch wide or less, while sanded grouts work best for wider grout lines.

Mix powdered grout in a small bucket, using a margin trowel. Begin by adding 1/2 of the recommended amount of water in a plastic bucket, then add 1/2 of the recommended amount of dry grout powder. Mix thoroughly, then add more water and more grout powder gradually until you have a full batch, or enough to cover about 3 to 4 feet square. The proper mixture should have a smooth, paste-like consistency that is just barely pourable. ​

Some grout may have instructions to allow the mixture to sit (slake) for a short period before applying. If so, follow the manufacturer's instructions regarding this.

Fill the Grout Joints

Scoop up a load of grout with a rubber grout float, and smear it onto the tile surface. Spread the grout over the joints, holding the float at an angle of about 60 degrees and pressing the grout fully into the joints. Work in alternating directions to make sure the joints are completely filled. Gather any excess grout and move it to the next area of tile, or reload the tile as needed. Repeat the same process until all of the joints are filled.

The grout float should be moved diagonally across the joint lines to ensure a uniform fill. If tiles have a rounded or beveled edge, the joints may need to be tooled. Tooling is the process of removing the upper layer of grout, leaving a thinner professional-looking joint. There are special tools that can be purchased for this, or simply drag the round tip of a pencil eraser along the joint when the grout has slightly dried.

Sponge the Joints and Tiles

Once all grout lines are filled and tooled, use a moistened sponge to remove excess grout. Make sure the sponge is barely wet—too much water will pull grout out of the seams. Lightly stroke the sponge across the tile surface without pressing too hard. 

This is a slow process. Continue to clean out your sponge and wipe it across the tile surface, moving diagonally across the joints, until all excess grout is gone. Don't worry about cleaning the surfaces of the tile completely; that will come next. Rinse the sponge frequently in the water, and change the water as it becomes dirty.

Remove the Grout Haze

Once the grout has dried completely (or as directed), a faint haze will still be present on the surface of the tiles. Use a soft cloth to buff the surfaces of the tile and remove any remaining haze. If you wish, you can use a haze-removing product to polish the tiles.