How to Regrout Shower Tile (Step by Step)

Cracked, crumbling, or stained grout is more than a cosmetic problem. In a shower, failed grout lets water behind the tile, where it rots the backer board, feeds mold, and eventually causes tiles to fall off the wall. Learning how to regrout shower tile is one of the highest-value DIY skills a homeowner can pick up: the materials cost $30 to $60, the job takes a weekend, and it can add years to the life of a shower that would otherwise need a full remodel. This guide walks through every step, from removing the old grout to sealing the new joints.

Signs Your Shower Needs Regrouting

Grout fails gradually, and the early signs are easy to miss. Look for cracks running along the grout lines, especially at the corners where walls meet and where the wall meets the tub or shower floor. Crumbly grout that powders when you scratch it with a fingernail is past its useful life. Dark, stained grout that will not come clean no matter how hard you scrub is usually harboring mold inside the pores.

More serious signs point to water getting behind the tile. Tiles that sound hollow when you tap them have lost their bond to the wall. Tiles that flex or move when pressed are a red flag. A musty smell in the bathroom that persists after cleaning, or paint peeling on the wall behind the shower, can mean water has been leaking through failed grout for months. If you see any of these signs, regrout soon. The longer water gets behind tile, the more expensive the repair becomes.

Not every shower problem is a grout problem. If the grout lines are intact but the caulk at the corners is cracked or peeling, you only need to recaulk, which is a much smaller job. If tiles are falling off or the wall feels soft and spongy, the backer board is damaged and regrouting alone will not fix it. In that case, the shower needs a partial rebuild, and a professional should assess the damage.

Tools and Materials You Need

Regrouting requires a few specialized tools, but none of them are expensive. You need a grout saw or an oscillating multi-tool with a grout removal blade, a utility knife, a grout float, a grout sponge, a bucket, a margin trowel, painter tape, safety glasses, a dust mask, and rubber gloves. A shop vacuum helps keep the dust under control.

For materials, you need grout, grout sealer, and caulk. Buy grout in the right type for your joint width: unsanded grout for joints under 1/8 inch, sanded grout for joints 1/8 inch and wider. Most shower wall joints are 1/8 inch, so unsanded grout is the common choice, while shower floors with wider joints usually need sanded grout. Buy a penetrating grout sealer, not a surface coating, and pick up a tube of 100 percent silicone caulk in a matching color for the corners.

Budget $30 to $60 for materials on a standard tub surround, and $60 to $100 for a large walk-in shower. An oscillating multi-tool costs $40 to $80 if you do not already own one, and it makes grout removal dramatically faster than a hand grout saw. Plan for the shower to be out of use for at least 48 to 72 hours while the grout cures and the sealer dries.

Step 1: Remove the Old Grout

Start by taping off the tub, the shower floor drain, and any fixtures you want to protect from dust and debris. Put on safety glasses and a dust mask. Grout removal creates a lot of fine silica dust, and you do not want to breathe it.

Work with a grout saw or an oscillating tool along every grout line you plan to replace. Remove the old grout to at least two-thirds of its depth, ideally all the way down to the backer board in the worst spots. The new grout needs enough depth to bond properly. A shallow skim of new grout over old grout will crack and fall out within months.

Take your time and keep the blade centered in the joint. The most common beginner mistake is letting the tool wander and chipping the edge of a tile. A chipped tile edge is visible forever, so slow, steady passes beat fast, aggressive ones. Work in small sections, and vacuum out the dust frequently so you can see what you are doing. Expect this step to take two to four hours for a standard tub surround, and most of a day for a large walk-in shower.

Step 2: Clean and Prep the Joints

Once the old grout is out, vacuum every joint thoroughly, then wipe the tile faces and the joints with a damp sponge. Any dust left in the joints will weaken the bond of the new grout. If you see mold or mildew in the joints, scrub them with a solution of one part white vinegar to one part water, or a commercial mold remover, and let the area dry completely.

Check every tile before you grout. Press each tile firmly and tap it with your knuckle. Tiles that move, flex, or sound hollow need to be re-set before grouting, because grout will not hold a loose tile in place. If you find loose tiles, remove them, clean off the old thinset, and re-set them with fresh thinset mortar. Let the thinset cure for 24 hours before grouting.

Let the shower dry completely before you start grouting. Damp joints dilute the grout and weaken it. If the shower was used recently, wait at least 24 hours, and run the bathroom fan to speed drying. This waiting is boring but essential. Grouting over damp joints is one of the most common reasons a regrout job fails early.

Step 3: Choose the Right Grout

There are three main types of grout, and the choice matters more than most homeowners realize. Cement grout is the traditional choice: cheap, easy to work with, and available everywhere. It comes in sanded and unsanded versions. Its weakness is porosity. Cement grout absorbs water and stains, which is why it needs sealing and why it eventually fails in a shower.

Epoxy grout is the premium choice. It is a two-part resin system that is essentially waterproof, stain-proof, and far more durable than cement grout. It costs three to four times as much and sets faster, which makes it harder to work with, but for a shower floor and the lower walls where water sits, it is worth every penny. Many professionals now use epoxy grout for the entire shower.

Urethane grout sits between the two. It is premixed, flexible, stain-resistant, and does not need sealing. It is a good middle option for a DIYer who wants better durability than cement grout without the fast set time of epoxy. Whichever type you choose, match the color to the existing grout or pick a slightly darker shade, since grout always dries a touch lighter than it looks wet.

Step 4: Apply the New Grout

Mix the grout according to the package directions. For cement grout, add powder to water slowly and mix to a thick peanut-butter consistency, then let it slake for 10 minutes and remix. Do not add extra water to make it easier to spread. Runny grout shrinks, cracks, and weakens as it dries. If you are using epoxy or urethane grout, follow the manufacturer instructions exactly, since the working time is shorter.

Load grout onto a rubber grout float and spread it across the tile at a 45-degree angle to the joints, pressing firmly so the grout packs deep into every joint. Work in sections of about three to four square feet at a time. After filling a section, hold the float almost flat and scrape diagonally across the joints to remove the excess. Repeat until all the joints in the section are full and even.

Wait 15 to 30 minutes for the grout to firm up, then wipe the tile with a damp grout sponge, using light, diagonal strokes. Rinse the sponge frequently and wring it out well. A sponge that is too wet will pull grout out of the joints. After the first wipe, let the grout haze dry for an hour, then buff the tile with a dry cloth. If a stubborn haze remains after 24 hours, a grout haze remover will take it off. Do not use the shower for at least 24 to 48 hours while the grout cures.

Step 5: Seal the Grout

Sealing is what makes a regrout job last. Cement grout is porous, and without a sealer it will absorb water, stain, and grow mold within months. Wait until the grout has cured fully, usually 48 to 72 hours for cement grout, before sealing. Check the grout package for the exact cure time.

Apply a penetrating grout sealer with a small foam brush or an applicator bottle, working it into every grout line. Wipe any excess off the tile immediately, since dried sealer leaves a hazy film. Let the first coat dry for the time specified on the bottle, usually a few hours, then apply a second coat for maximum protection. Epoxy and urethane grout do not need sealing, which is one of their advantages.

Test the seal by dropping a few beads of water on a grout line. If the water beads up, the sealer is working. If it soaks in and darkens the grout, apply another coat. Reseal cement grout once a year to keep the shower protected. After sealing, recaulk the corners and the joint where the wall meets the tub or floor with 100 percent silicone caulk. Never grout those corners: they are movement joints, and grout there will crack. Caulk flexes, grout does not.

Mistakes to Avoid

The most common regrouting mistake is grouting over old grout instead of removing it. A thin skim of new grout has nothing to grip and will crack and flake within weeks. Always remove the old grout to at least two-thirds depth. The second most common mistake is grouting over loose tiles. Grout is not glue. A loose tile needs to be re-set with thinset first.

Another frequent error is using the wrong grout for the joint width. Sanded grout in narrow joints will not pack properly and will look rough. Unsanded grout in wide joints shrinks and cracks. Check your joint width and buy accordingly. A fourth mistake is skipping the sealer, or sealing too early before the grout has cured. Sealer applied over uncured grout traps moisture and weakens the grout.

Finally, do not rush the cure time. Using the shower before the grout has cured washes out the fresh grout and ruins the job. Wait the full 48 to 72 hours, and keep the bathroom well ventilated while it cures. If your shower has other problems, like a failing valve or a worn drain, now is a good time to fix them. See our shower valve replacement cost guide and our shower drain installation guide for help. For the full picture of shower work, browse our shower and tub hub.