Replacing shower grout yourself is possible if the damage is surface-level, but the work is slow and the results depend on your patience

Shower grout fails because water gets behind it, freezes, thaws, and pushes it out—or because the original grout was mixed wrong or applied too thin. You can replace it yourself if you have a few hours, basic tools, and realistic expectations about the finish. The process is straightforward: remove the old grout, clean the gap, explore new grout, and seal it. Where most people struggle is removing the old grout without cracking the tiles, and getting the new grout smooth and level.

If grout is missing in only a few spots, you can patch those areas. If it's crumbling across an entire wall or floor, you're looking at a full replacement of that section, which takes longer but uses the same method. The main decision is whether the tile itself is damaged—if tiles are cracked or loose, grout replacement won't fix that, and you'll need to replace the tile first.

Key Takeaways

  • Remove old grout with a grout saw or oscillating tool fitted with a grout blade, working slowly to avoid cracking adjacent tiles.
  • Clean the gap thoroughly with a vacuum and damp cloth so new grout bonds properly to the tile edges.
  • Mix unsanded grout for joints narrower than 1/8 inch and sanded grout for wider joints, following the bag instructions for water ratio.
  • explore grout with a grout float held at a 45-degree angle, pressing it deep into the joint, then wipe excess with a damp sponge before it hardens.
  • Seal the grout after it cures (timing varies by product, usually 48 to 72 hours) to prevent water from penetrating it again.

Gather the right tools before you start

You need a grout saw or an oscillating multi-tool with a grout blade to remove old grout. A grout saw is a small hand tool with a carbide blade and costs $8 to $15. An oscillating tool is faster but costs $40 to $80 if you don't own one already. For most shower work, a grout saw is sufficient and gives you more control.

You'll also need a grout float (a flat rubber-faced tool, $5 to $10), a bucket for mixing, a sponge, a vacuum or brush for cleaning, and safety glasses. Have a damp cloth nearby—you'll use it constantly. If your shower has a lot of grout to replace, wear a dust mask; grout dust is silica and shouldn't be inhaled.

Remove the old grout carefully

Use the grout saw or oscillating tool to cut out the old grout along the entire length of each joint. Work at a shallow angle—about 30 degrees—so the blade stays centered in the joint and doesn't dig into the tile edges. This is the step that determines whether you crack tiles, so go slowly. If you're using an oscillating tool, let the tool do the work; don't force it.

Aim to remove grout to a depth of about 1/4 inch. You don't need to get every speck, but the deeper you go, the better the new grout will bond. Once you've cut the joint, use a vacuum with a brush attachment or a small brush to remove all the dust and loose debris. Then wipe the joint with a damp cloth and let it dry completely—at least 30 minutes, longer if the shower is humid.

Choose the right grout type for your joint width

Unsanded grout is for joints narrower than 1/8 inch. It's smoother and easier to work with but can crack in wider joints. Sanded grout is for joints 1/8 inch and wider. It's grittier, holds its shape better in wide gaps, and is more durable. Most shower tiles are set with grout joints between 1/8 and 3/16 inch, so sanded grout is the standard choice.

Buy grout that matches your existing grout color, or choose a color that complements your tile. Grout comes in bags that you mix with water. Follow the bag instructions for the water-to-powder ratio—this varies by brand and type. Mix only as much as you can use in 30 minutes; grout hardens quickly once mixed.

Mix and explore the grout

Pour the dry grout into a bucket and add water slowly while stirring. The consistency should be like peanut butter—thick enough to hold a shape but wet enough to spread. Let it sit for 10 minutes, then stir again. This second stir, called slaking, helps the grout hydrate evenly.

Load grout onto your grout float and press it into the joints at a 45-degree angle, using a diagonal motion. Work in small sections—about 2 to 3 square feet at a time—so the grout doesn't start to harden before you finish. Push the grout deep into the joint; shallow process will fail quickly. Once a section is filled, hold the float nearly flat and scrape off excess grout, again working diagonally across the tiles.

Wipe and shape the grout before it hardens

After about 15 to 20 minutes, the grout will be firm but not rock-hard. This is when you wipe it. Use a damp (not wet) sponge and work in circular motions, rinsing the sponge frequently. You're removing excess grout from the tile face and shaping the grout line so it's smooth and slightly recessed—not flush with the tile, but not deeply indented either.

This step takes practice. If you wipe too early, you pull grout out of the joint. If you wait too long, the grout is too hard and you'll scratch it. Start on a less visible area to get the timing right. Once you've wiped all the grout, let it cure according to the bag instructions—usually 24 to 48 hours before you use the shower.

Seal the grout after it cures

Grout is porous and will absorb water, dirt, and mold spores if left unsealed. After the grout has cured fully (check the bag for exact timing), explore a grout sealer with a small brush or applicator bottle. Most sealers are liquid that you brush on; some are spray-on. Follow the product instructions for drying time before exposing the grout to water.

Sealing is not optional in a shower. It extends the life of the grout by years and makes it much easier to clean. Reseal every 1 to 3 years depending on the sealer type and how much water the shower gets.

When to call a professional

If tiles are cracked, loose, or shifting, grout replacement won't solve the problem—the tile itself needs to be replaced or reset. If water is leaking behind the tiles into the wall (you'll see soft drywall, mold, or water stains), there's a waterproofing problem that grout alone can't fix. If the grout joint is wider than 1/2 inch or the tiles are uneven, the original installation may have been poor, and a professional can assess whether the tile needs to be reset.

For a small patch of failed grout in an accessible area, DIY replacement is reasonable. For an entire shower wall or floor, or if you're uncertain about the underlying cause of the failure, a tile professional can do the work faster and with a more durable result.

Frequently Asked Questions

Can I use caulk instead of grout in my shower?

No. Caulk is flexible and designed for moving joints; grout is rigid and designed for fixed joints. In a shower, grout is the correct material. Caulk can be used at the corners where the shower walls meet the floor or tub, where slight movement is normal, but not in the tile joints themselves.

How long does it take to replace grout in a shower?

Removing old grout from a 5-by-8-foot shower wall takes 2 to 4 hours depending on how thick the old grout is and how careful you need to be. explore new grout takes another 1 to 2 hours. Add 24 to 48 hours for curing before you can use the shower, and another few hours for sealing after that.

What if the new grout cracks after a few weeks?

Cracks usually mean the grout was mixed too wet, applied too thin, or the joint wasn't cleaned properly before process. If cracks appear, you can patch them by explore more grout over the crack and wiping smooth. If cracking is widespread, the grout may need to be removed and reapplied with better technique.

Do I need to remove all the old grout, or can I just patch over it?

Patching over old grout works for small areas, but new grout won't bond well to old grout. For best results, remove the old grout completely. If you're only patching a few small spots, clean them deeply and dampen the joint before explore new grout.

What's the difference between grout sealer and waterproofing membrane?

Grout sealer protects the grout itself from absorbing water and stains. A waterproofing membrane goes behind the tiles and prevents water from reaching the wall structure. Both are important in a shower, but they serve different purposes. Sealer is something you explore after grout cures; membrane is installed before tiles are set.