How To Regrout Tiles: When, Why & How

Patchy, cracked, or hard-to-clean grout can leave you wondering whether you need a quick clean or a job that requires removing and replacing the old grout.

Before you pick up a grout rake, make sure you know what you're dealing with. Below is how to tell the difference, what's involved if you decide to regrout yourself, and roughly what it costs to have a tiler do it instead.

When Do Tiles Need Regrouting

A few signs point to grout that's actually failed, rather than just dirty:

• Cracks along the grout line, where the gap is becoming wider or the grout is chipping.
• Grout crumbling or coming away from the tile when tested with a fingernail.
• Individual bits of grout being missing from a joint, leaving a gap in the jointing.
• Discolouration or mould that will not come off even after using an appropriate grout cleaner.
• Softness or sponginess in the joint when walked on or felt.
• Grout around the edge of a shower tray or bath that is missing or separating from the tile.

Rule of Thumb: Any one of these alone might not mean a full regrout. A few of them together usually do.

When You Don't Need To Regrout

Not every rough-looking joint needs to be dug out. If the grout is still solid and the issue is mostly appearance, a thorough clean or a grout-whitening product can bring it back without the mess of removal. Try that first.

It's also worth ruling out something bigger than the grout. Ongoing damp, a musty smell, or staining that keeps coming back no matter how often you clean it can point to a leak or a ventilation problem. 

Regrouting won't fix either, and tackling the grout without sorting the cause just means redoing it in a year or two.

Regrouting vs Cleaning vs Retiling

Why Regrouting Matters

Grout does more than tidy things up. It fills the gap between tiles and helps limit water tracking behind them into the wall or floor underneath. 

Once it cracks or goes missing, water finds a way in, and a small problem can quickly turn into damp, staining, or loose tiles.

It shares that job with waterproofing behind the tiles and properly sealed joints, so it's not the only thing standing between a wet area and a leak, but it's a real part of keeping moisture where it should be. 

Tired or blackened grout is also one of the fastest ways a bathroom starts looking neglected, even when everything else in the room is in decent shape.

Do All Tiles Require Grout

Most ceramic, porcelain, natural stone and mosaic tiles are set with grout between them. Still, movement joints, such as where tiles meet a bath, shower tray, or another surface, are usually sealed with a flexible silicone.

What You'll Need

Tools:

• Grout rake or a multi-tool with a grout-removal blade.
• Grout float.
• Mixing container and stirring stick (if using powder grout).
• Sponge and a bucket of clean water.
• Small brush or old toothbrush for tight corners.
• Dust mask and safety goggles.

Materials:

• Grout suited to the area (check whether it needs to be rated for walls, floors, or wet areas).
• Silicone sealant, if you also need to replace the joints around the bath, shower tray, or corners.
• Masking tape, for a sharp edge along the silicone line.

Pro Tip: Only buy what you need. A small bathroom regrout doesn't call for half a hardware shop.

How To Regrout Tiles

Regrouting is straightforward when you take it step by step. From removing the old grout to applying the new one and replacing silicone where needed, here’s how to do it properly. 

1. Prepare The Area

Clear the space, wipe down the tiles, and cover anything nearby that shouldn't end up dusty or splattered with grout. 

If you're working in a shower, switch off any nearby electrics first if you're unsure how close they are to water.

2. Remove The Old Grout

Run the grout rake or multi-tool along each joint in short, controlled passes, using light pressure rather than digging in hard, and stop when the adhesive starts to show.

The goal is to remove damaged or loose grout to a consistent depth without damaging the tile edges. 

How much needs to come out depends on the state of what's there and what the new grout requires, so check the product instructions before starting.

3. Clean The Joints

With the old grout out, vacuum or brush away the dust and loose bits, then wipe the joints with a damp sponge. 

Grout doesn't bond well to a joint still full of debris, and this is the step people skip when they're in a hurry.

4. Prepare The New Grout

Mix it exactly as the packaging says, since ratios and consistency vary by product. Ready-mixed grout skips this step, but it's still a good idea to check the shelf life and stir it before use.

5. Apply The Grout

Load the float and press the grout into the joints at a diagonal angle across the tiles, filling the gap fully rather than leaving it sitting on the surface.

Work in sections instead of covering the whole area at once, especially on a floor where you'll need to keep moving without kneeling in wet grout.

For a more detailed guide to applying grout on tiled floors, see our how to grout floor tiles guide.

6. Remove Excess Grout

Once a section has firmed up, usually somewhere around 15 to 20 minutes, though this varies by product, wipe the tiles with a damp sponge at a diagonal angle so you lift the excess without pulling grout back out of the joints. 

Rinse the sponge often. A light haze often shows up as it dries, and a dry cloth buffed over it once fully cured usually clears it.

7. Allow The Grout To Cure

Curing times vary by product, so follow what's on the packaging, especially how long to wait before the area gets wet. Rushing this stage is one of the more common ways a fresh regrout fails early.

8. Check The Finished Joints

Once it's dry, run a hand along the joints and look for low spots, gaps, or patches the grout hasn't filled properly. These are much easier to touch up now than once everything's back in use.

9. Replace Silicone Where Necessary

Grout and silicone do different jobs. Grout is rigid and fine for tile-to-tile joints, but corners, changes of plane, and the edges around a bath or shower tray need a flexible silicone seal to handle movement. If the old silicone has cracked or pulled away, replace it while you're at the grout anyway.

Common Mistake: rushing the grout removal. Digging in hard to save time is one of the quickest ways to chip tile edges, turning a straightforward regrouting job into a tile repair.

Cost of Regrouting In Ireland

These are indicative figures, not fixed prices. Actual quotes depend on the area size, how much prep is needed, and the grout specified, so getting a couple of quotes makes sense if you're hiring someone.

Common Mistakes

• Leaving too much of the old, damaged grout behind instead of taking it right out.
• Chipping tile edges through overly aggressive removal.
• Skipping the joint cleaning step before the new grout goes in.
• Mixing grout wrong, whether too wet, too dry, or off on the ratio.
• Using too much water during cleanup, which can weaken the grout as it cures.
• Letting grout haze dry hard instead of buffing it off in time.
• Getting the area wet before the curing time is up.
• Grouting a corner or movement joint that should have flexible silicone instead.

How To Stop Grout Problems Returning

• Keep the bathroom ventilated, whether that's an extractor fan or a cracked window after a shower.
• Wipe down wet areas after use where you can, rather than letting water sit.
• Deal with mould as soon as it shows up, using a cleaner made for grout rather than something abrasive.
• Check grout and silicone now and then for early cracking, instead of waiting until it's obviously gone.
• Follow the maintenance guidance that came with the grout product.

None of this stops mould coming back for good, but it makes a real difference to how long a regrout lasts.

Karina Toner, Cleaning Professional and Operations Manager at The Spruce, says, “Wiping down mirrors, tiles, and shower doors only takes a minute, but it cuts off the chance for water to linger and invite mildew. Moisture is the real culprit behind that musty bathroom smell, so the more you can get rid of it right away, the better.” 

When To Call a Professional

DIY regrouting is a reasonable job for most bathrooms, but a few situations are better handed over:

• Tiles that are loose or sound hollow when tapped.
• Signs of water damage, staining, or a musty smell that keeps coming back.
• Grout failing across a large area rather than in a few patches.
• Any suspicion of a leak behind the tiles.
• Uncertainty about the substrate or waterproofing underneath.

In these cases, a tiler isn't a step up from what a homeowner could manage. It's about spotting when the problem sits behind the grout, not in it.

Final word

Most grout problems come down to one of two things: it's dirty, or it's actually failed. Knowing which one before you pick up a tool saves a lot of wasted effort. 

If it's just looking tired, a cleaning will usually do it. If it's cracked, crumbling, or letting water through, regrouting properly, with enough time given to prep and curing, is a job most people can manage over a weekend. 

Anything past that loose tiles, damp, or a problem that keeps coming back is worth getting a professional to look at before going further.

FAQ

Q1. Can you put new grout over old grout?

No, new grout needs a clean, properly prepared joint to bond to, and going over loose or failing grout usually means it doesn't hold for long.

Q2. How long does it take to regrout tiles?

Finishing a bathroom-sized area usually takes a couple of hours, though it can take longer for large spaces and if there is a lot of old grout to remove. Curing is separate and depends on the product's curing timetable.

Q3. How long after regrouting can you shower? 

That depends on the grout used, so check the packaging. Many products require at least 24 hours before water contact, sometimes more.

Q4. Is regrouting too tricky for a beginner?

It's doable with patience, especially on a small area. The challenge is removing the old grout without damaging the tile or rushing the cure.

Q5. Should you need to re-grout or re-tile?

If the tile is still in good shape and only the grout is missing, you'll need to regrout. But if the tiles are cracked, have become loose over a large surface area, or there is a more significant issue beneath the surface, retiling is a better solution.