How to Regrout a Shower: Step-by-Step Guide (2026)

Frequently Asked Questions

How do I know if my shower grout needs replacing?

Replace grout when it's cracking, crumbling, or pulling away from the tiles — that's a water intrusion risk. Black or pink mold that doesn't clean off with mold remover also warrants regrouting. Discolored-but-intact grout that's structurally sound can often be cleaned rather than replaced. Press on the grout — if it flexes or crumbles, replace it.

Can I grout over old grout?

No. New grout applied over old grout doesn't bond properly and will crack and fall out within months. The old grout must be removed to a depth of at least 1/4 inch so the new grout has enough tooth and depth to bond. Skipping removal is the #1 cause of failed regrout projects.

What type of grout should I use in a shower?

For shower tile with joints under 1/8 inch wide: unsanded grout. For joints 1/8 inch or wider: sanded grout. For a wet area like a shower, use a grout rated for wet environments — Laticrete SpectraLOCK, Mapei Ultracolor Plus FA, or Fusion Pro single-component grout. Avoid standard unsanded grout in horizontal shower floors — it's less durable under foot traffic and water pooling.

How long does regrouting a shower take?

Plan for 3 days minimum: Day 1 — grout removal (2–4 hours depending on shower size). Day 2 — grout application, cleanup, and initial cure (2–3 hours active work, then 24 hours dry time). Day 3 — sealer application (30 minutes). Add another 24 hours before using the shower after sealing.

Do I need to seal grout in a shower?

Yes, for cement-based grout (sanded and unsanded). Grout is porous and absorbs water, soap scum, and mold spores without sealer. Epoxy grout (like Fusion Pro or SpectraLOCK) is non-porous and doesn't need sealing. Apply sealer 72 hours after grouting and reapply every 1–2 years in a shower.

What's the difference between grout and caulk in a shower?

Grout fills the joints between tiles. Caulk fills the change-of-plane joints — the corners where walls meet, and where the wall meets the tub or shower floor. Change-of-plane joints need caulk, not grout, because those areas flex with the building's movement. Grout at change-of-plane joints always cracks. When regrouting, replace the corner caulk as well — use a mold-resistant 100% silicone caulk.

Regrouting a shower takes 4–6 hours of active work over 2 days (grout removal day 1, grout application and initial cure day 2, sealing day 3). Use an oscillating multi-tool or grout saw to remove the old grout to a depth of 1/4 inch, vacuum thoroughly, apply unsanded grout (for joints under 1/8 inch) with a rubber float, clean with a damp sponge, and seal after 72 hours.

Shower grout fails for one reason: water gets behind it. Once cracking or mold reaches the point where cleaning doesn’t fix it, regrouting is the right repair — not caulk over the top, not mold spray, not new tiles. The job is straightforward but requires patience and the right removal tool. Here’s the complete process.

Step 1: Assess what you’re regrouting

Before buying anything, look at the full shower and categorize what you see:

Tile-to-tile joints (flat surface): These get grout — either sanded (joints 1/8 inch or wider) or unsanded (joints under 1/8 inch).

Corner joints and floor-to-wall transition: These get caulk, not grout. The building moves, and caulk flexes with it. Grout here always cracks within a year.

Cracked single tiles: If tiles are cracked or loose, address those first before regrouting — loose tiles indicate failed thinset underneath, not just failed grout.

What you’ll need

Removal tools

• Oscillating multi-tool with grout removal blade — the fastest method, works on all joint widths
• Or manual grout saw — slower but more control, better for narrow joints
• Shop vac for dust and debris

Grouting supplies

• Unsanded grout for joints under 1/8 inch (most wall tile)
• Sanded grout for joints 1/8 inch or wider (most floor tile)
• Or single-component grout (no mixing required, pre-mixed, non-sanded, doesn’t need sealing)
• Rubber grout float
• Grout sponge — large, coarse sponge, not a regular kitchen sponge
• Bucket for mixing (if using powder grout) and rinse water
• Grout sealer (skip if using epoxy or Fusion Pro)

Finishing

• Mold-resistant silicone caulk for corners and change-of-plane joints
• Caulk gun
• Blue painter’s tape

Day 1: Remove the old grout

This is the most physically demanding part. Work in sections and take breaks — grout removal is slow.

Using an oscillating multi-tool (recommended):

1. Fit the oscillating tool with a grout removal blade. Set to medium speed.
2. Run the blade along the center of the grout joint. Let the tool do the work — don’t press hard or you’ll chip tile edges.
3. Target depth: 1/4 inch minimum (about the depth of a pencil eraser). Run two passes if needed.
4. Work in one direction across all horizontal joints first, then all vertical joints.
5. Vacuum frequently — grout dust builds up fast and obscures the joint.

Using a manual grout saw:

1. Score the center of the joint first with a light pass.
2. Work the saw back and forth in the joint to gradually deepen it to 1/4 inch.
3. For narrow joints (under 1/16 inch), a manual saw gives you more control than a power tool.

What you’re looking for: The joint should look clean and slightly rough at 1/4 inch depth, with no powdery old grout residue clinging to the sides. Solid, well-bonded old grout below 1/4 inch can stay — it’s only the surface layer that needs to come out.

Corners and caulk joints: Use a utility knife or caulk remover tool to cut out old caulk from corners. Don’t use the oscillating tool here — the vibration can crack tile at corners.

Final cleanup: Vacuum all joints thoroughly. Then wipe the joints with a damp rag to remove fine dust. Let dry completely before grouting — damp joints prevent proper adhesion.

Day 2: Apply new grout

Timing matters: Don’t grout until the joints are fully dry (at least a few hours after cleaning, or overnight).

Mix the grout (powder grout)

1. Pour the grout powder into a clean bucket.
2. Add clean water gradually (the bag lists the ratio). Start with slightly less water than called for.
3. Mix with a margin trowel until smooth — consistency should be like creamy peanut butter. No dry lumps, no runny spots.
4. Let the mix slake for 5–10 minutes, then stir again. This activates the cement chemistry.

Pre-mixed grout: Skip the mixing. Open and use directly from the container.

Apply the grout

1. Wet the tile surface slightly with a damp sponge — this slows suction so you have working time.
2. Load the rubber float with grout and press it diagonally across the joints at a 45-degree angle to the tile surface. Work in 3–4 square foot sections.
3. Force grout into the joints by pressing firmly and sweeping across the surface. Work diagonally — going straight along a joint pulls grout back out.
4. Once joints are filled, hold the float at a 90-degree angle and sweep diagonally across the tile surface to scrape off excess. Keep the face of the float clean to avoid dragging excess back into joints.

Clean the tile surface (critical timing)

The timing of cleanup determines whether you spend 30 minutes or 3 hours cleaning tile later.

1. Wait 15–20 minutes after applying grout (this is the window — too early and you pull grout from joints; too late and haze becomes cement-hard).
2. Dampen the grout sponge in clean water and wring it out thoroughly — the sponge should be barely wet, not dripping.
3. Wipe the tile surface in circular motions to remove the grout film. Rinse the sponge frequently and change the rinse water often.
4. A light haze will remain — this is normal. Let it dry for 20–30 minutes.
5. Buff the haze off with a dry microfiber cloth. Light haze comes off easily at this stage.

If haze hardens: Use grout haze remover. Dilute per instructions and apply with a sponge, then scrub with a nylon brush. This is a strong acid — wear gloves and ventilate.

Let cure

Allow 24–48 hours before using the shower. Cement-based grout continues hardening for 28 days — avoid harsh cleaners for the first month.

Day 3: Caulk corners + seal grout

Caulk the change-of-plane joints

1. Apply painter’s tape along both sides of every corner joint and where the wall meets the floor/tub.
2. Cut the caulk tube nozzle at a 45-degree angle to match the joint width.
3. Apply a smooth bead of mold-resistant silicone caulk into the joint in one continuous motion. Don’t stop and start.
4. Wet your fingertip or use a caulk finishing tool to smooth the bead. Pull the tape immediately while the caulk is still wet.
5. Let silicone cure 24 hours before water contact.

Seal the grout

1. Wait at least 72 hours after grouting before sealing (or 48 hours for fast-setting grout).
2. Apply grout sealer with a brush or foam applicator directly along the grout lines. Avoid getting sealer on the tile face.
3. Let it absorb for 5–10 minutes, then wipe off any excess on the tile surface.
4. Apply a second coat in 30 minutes.
5. Wait 24 hours before using the shower.

Sealer lifespan: Reapply every 1–2 years in a shower. Test with the water drop test — if water soaks in within 5 minutes, reapply.

Common mistakes

Not removing enough grout. If you leave less than 1/4 inch depth, the new grout has no mechanical grip and will fail early. The minimum is 1/4 inch — more is fine, less is not.

Grouting the corners. Corners flex. Grout doesn’t. Every corner joint in a shower should be caulk, not grout. This is the most common cause of shower water damage.

Over-wetting the sponge during cleanup. A dripping sponge washes grout out of the joints. The sponge should be barely damp — wring it almost dry before using.

Grouting in a cold or dry environment. Grout needs 65–85°F and moderate humidity to cure properly. Air conditioning blowing directly on fresh grout dries it too fast, causing cracking.

Using the wrong grout type. Sanded grout in a 1/16-inch joint scratches soft tiles (marble, glass). Unsanded grout in a wide joint shrinks as it cures and cracks. Match grout type to joint width.

When to call a professional

• Tiles are loose, hollow-sounding, or moving — that’s a substrate problem, not a grout problem
• You see water stains on the ceiling below the shower — the liner has already failed, regrout won’t fix it
• Mold has gotten behind the tile (grout removal reveals black mold on the wall) — requires tile removal and substrate repair

Related guides

• How to Grout Tile — full grouting technique for new tile work
• How to Tile a Bathroom Floor — full tile installation when regrout isn’t enough
• How to Caulk a Bathtub — the corner treatment that goes with every regrout job
• How to Clean Grout — if the grout is intact but stained
• Bathroom Remodel Cost Breakdown — full renovation pricing when it’s time for more than regrout
• How to Fix a Floor Tile That Is Loose — reattach hollow floor tiles before regrouting around them
• How to Fix a Bathroom Tile That Fell Off — reattach wall tiles that have fully detached before regrouting the surround
• How to Fix a Broken Tile in Shower — replace a cracked or broken shower wall tile before regrouting
• How to Fix a Broken Tile Grout — repair crumbling or missing grout joints as a targeted alternative to full regrout
• How to Fix a Broken Bathroom Tile Floor — replace broken bathroom floor tiles while you have grout tools and thinset available
• How to Fix a Broken Tile Shower Niche — repair a cracked or leaking recessed shower niche while regrout tools are out
• How to Fix a Cracked Bathroom Tile — replace a single cracked floor or wall tile before regrouting the surrounding joints
• How to Fix a Cracked Ceramic Bathroom Tile — repair or swap a cracked ceramic tile before regrouting the shower surround
• How to Fix a Cracked Fiberglass Tub — repair a fiberglass tub crack before regrouting surrounding tile walls
• How to Fix a Cracked Fiberglass Tub Surround — repair a cracked surround panel before regrouting the perimeter tile joints