Cracked Grout in Your Shower: Causes, Repair and Cost

A few hairline cracks in shower grout are common and not an emergency, but you shouldn’t ignore them. Grout is porous and was never waterproof, so every crack gives water a route behind the tiles. A cracked line in one spot can often be raked out and redone. Cracks that return, run in a line or sit in a corner point to a different problem, and a quick patch won’t fix it.

This guide explains why shower grout cracks, how to tell a cosmetic problem from a damp one, how a lasting repair is done, and what UK homeowners should expect to pay.

TL;DR

• Cracked grout is a warning sign, not just a cosmetic flaw. Grout and tiles are water-resistant, not waterproof, so water can reach the adhesive and the wall behind.
• You can’t grout over cracked grout. The old material has to be raked out to at least 2-3mm and the joint vacuumed clean first.
• Cracks in corners and where the wall meets the shower tray need flexible silicone, not grout. Using grout there is a leading cause of cracks coming back.
• Expect roughly £150 to £400 for a small patch repair and £300 to £800 for a full shower enclosure regrout and seal, often before VAT.
• If cracks keep returning, or tiles sound hollow or feel loose, the problem is likely behind the tile and needs a proper assessment.

Table of Contents

• Is cracked shower grout a problem?
• Why shower grout cracks
• What to check before you repair anything
• Can you just grout over cracked grout?
• How to repair cracked shower grout
• How much does it cost to fix cracked shower grout?
• Which tradesperson do you call?
• Our view: fix the joint, then fix the reason
• When regrouting is not enough
• Preventing cracks in the new grout
• Our tiling and shower work in Cardiff
• FAQ
• Sources

Is cracked shower grout a problem?

Yes, but how big a problem depends on where the crack is and how long it has been there.

Grout is a cementitious, porous material. Tiles and grout are water-resistant rather than waterproof, so a crack lets moisture soak toward the adhesive and the wall substrate. Over time that can mean loosened tiles, rotting boards and a bill far bigger than a regrout. Angi makes the same point: ignored damage can grow into larger, more expensive repairs.

A quick way to judge what you are looking at:

The forums are right that one hairline crack isn’t a crisis. Where they go wrong is treating all cracks alike. A crack in the tray junction that you leave for a year is a different matter from a crack in a wall joint at eye level.

Why shower grout cracks

Knowing the cause matters, because if you fix the symptom and not the cause, the crack comes back.

Grout used where it should not be

The most common reason for repeat cracks in corners is rigid grout in a spot that needs to flex. British Standard BS 5385 calls for changes of plane to be sealed with a flexible movement joint, such as silicone. That covers internal wall corners and the junction between wall tiles and the shower tray. Grout bridging those joints will crack every time the surfaces move, and a shower tray moves more than you think when someone stands in it and the tray warms and cools.

Grout mixed badly

If your shower is new and the grout is already cracking, look at the mix. Industry experts quoted by Angi say the usual culprit is too much water, added to make the grout easier to spread. The result is weaker, porous grout that powders and cracks within a year or two. Properly mixed grout has a thick consistency, roughly like peanut butter, and shouldn’t be thinned after it has rested.

Movement in the structure

Widespread or repeated cracking often points to the build, not to wear. According to a home inspectors’ association article on tiled showers, flexing walls, patchy adhesive coverage and blocked or poorly drained shower tray weep holes can make the whole system shift or trap water. That pressure forces grout to crack and crumble however well you repair it.

Missing waterproofing

Since the 2018 revision of BS 5385-1, wet area substrates are expected to be protected by a tanking membrane before tiling. If your shower was tiled without one, grout cracks carry more risk, because there’s no second line of defence behind the tile.

Plain old age

Even good grout breaks down. Family Handyman notes that tile itself is almost maintenance-free, while grout eventually deteriorates. In an older shower that has been used daily for fifteen years, some cracking is simply the end of the grout’s life.

What to check before you repair anything

Spend ten minutes on this first. It decides whether you need a regrout or a bigger conversation.

1. Tap the tiles. Gently knock along the cracked area with a knuckle. A hollow or dull sound compared with neighbouring tiles suggests the adhesive has let go.
2. Press the wall and floor. Any give, flexing or spongy feel near the shower tray is a red flag.
3. Look outside the shower. Check the ceiling of the room below, the skirting board and the wall on the other side for staining, bubbling paint or a musty smell.
4. Check the silicone. Is it black, peeling or separated from the tray? Failed silicone is a very common source of leaks, and it is far cheaper to fix than grout.
5. Note the pattern. One isolated crack and a crack running along an entire edge are different problems.

If you find signs of damp, stop treating this as a grout job. Cracked grout can hide moisture that has already damaged the adhesive or wall, and a fresh coat of grout would simply seal the problem in. If a vanity unit or cabinet sits against the affected wall, it is worth reading about which cabinet materials resist moisture best, since swollen or stained cabinet backs are another sign water has travelled.

Can you just grout over cracked grout?

No. New grout doesn’t bond to old, cracked grout, so it fails again quickly. The old material needs to be raked out to a depth of around 2-3mm so the new grout can lock into the joint.

The same goes for caulk-style fixes. Squeezing a bead of sealant over a cracked grout line may look tidy for a month, but it traps water and hides the damage. Sealant belongs in the movement joints, not on top of cracked grout lines.

How to repair cracked shower grout

If the area is small and you have found no sign of water damage, a careful repair is realistic. If you are renting, remember that your landlord should handle it. The steps below are the sequence a tiler follows, so you can also use them to judge a quote.

1. Let the shower dry fully. Don’t use it for a day or two and ventilate the room. Damp joints won’t take new grout properly.
2. Rake out the old grout. Use a grout removal tool or oscillating tool with care. Go to at least 2-3mm deep and avoid chipping the tile edges.
3. Vacuum out every trace of dust. Leftover dust stops new grout from bonding and leads to crumbling. Wipe the joints clean with a barely damp cloth afterwards.
4. Cut out failed silicone. Remove the old sealant at the tray and the corners completely, rather than laying new silicone over the old.
5. Mix the grout correctly. Follow the maker’s ratio, let it rest, and don’t add extra water. A stiff, paste-like mix is the goal.
6. Press the grout into the joints. Work diagonally across the joints with a rubber float, then wipe off the excess with a barely damp sponge.
7. Silicone the movement joints. Use a sanitary, mould-resistant silicone in internal corners and along the tray junction, never grout.
8. Leave it to cure. Follow the product’s guidance on cure time before showering, and check whether the grout needs sealing.

And for the sealant step, this is the one most DIY repairs skip. Without a flexible joint at the tray, a new grout line there will crack again within months.

Common mistakes

• Thinning the grout to make it spread easily.
• Filling corner joints with grout because it matches the colour.
• Raking too shallow, so the new grout only skims the surface.
• Showering too soon, before the grout has cured.
• Patching around loose tiles instead of lifting and re-fixing them.

How much does it cost to fix cracked shower grout?

For the UK, one 2026 cost guide puts a full shower enclosure regrout and seal at £300 to £800, depending on the scope and the damage already there. Small localised patch repairs run from £150 to £400. Quotes may exclude VAT at 20%.

A snagging-cost guide for new builds gives a similar picture for tiling and wet areas, including a range for replacing cracked tiles and regrouting. Treat any figure as a guide: prices in Cardiff and the Vale of Glamorgan will vary with access, tile size and the number of joints.

What changes the price most:

• Size of the enclosure. A walk-in shower with large wall areas has far more joint than a compact cubicle.
• Tile type. Small mosaic tiles mean many more joints to rake out.
• Silicone work. Stripping and replacing the perimeter seals adds time.
• Hidden damage. Loose tiles, soft boards or a failed tanking layer move the job from a regrout to a repair of the structure.

A tip when you compare quotes: ask what depth the grout will be removed to, whether the silicone joints are included, and whether the price covers a check for loose tiles. A cheap quote that only scrapes the surface will cost more in the end.

If you pay a professional to clean up after a larger job, there are services that handle after-builders cleaning, though these are based elsewhere in the UK, so check coverage for your area.

Which tradesperson do you call?

This trips up many homeowners. Plumbers deal with pipes, valves and leaks from supply or waste. Cracked grout and loose tiles belong to a tiler or bathroom fitter. A tiling specialist’s cost guide makes the point that calling a plumber for grout cracks is often a wasted call-out.

There is one exception: if you can’t tell whether the water is coming through the grout or from a pipe or the shower waste, the cause needs diagnosing before anyone regrouts. Look for a drip from the ceiling below, a wall that stays damp when the shower hasn’t been used, or a rising water bill. Those point to plumbing, and a team that covers both trades can sort it in one visit.

Our view: fix the joint, then fix the reason

We fit and renovate bathrooms across Cardiff and the Vale of Glamorgan, and cracked shower grout is something we see all the time. Our honest view: grout itself is rarely the real story.

When a homeowner calls about a cracked line, we first ask where it is. A crack mid-wall is usually just ageing. A crack in the corner or along the tray is nearly always a joint that should have been silicone, and it will be again in six months if someone just refills it with grout. And if the tiles are hollow or the room next door is damp, a regrout is the wrong job, however much cheaper it sounds.

That is why we like to deal with a bathroom as one accountable team, rather than passing the plumbing to one firm and the tiling to another. When the person looking at your shower can read both the pipework and the tile, you get one answer about what’s actually wrong, not two trades pointing at each other.

Our advice is simple. Repair small, isolated cracks promptly and properly. Treat repeat cracking as a symptom. And if the shower is old, tired and has been repaired before, put the repair money towards a proper replacement with correct waterproofing, not another patch.

— James

When regrouting is not enough

Sometimes a repair is the wrong answer. Consider a bigger job when:

• The same joints crack again within a year of being redone.
• Tiles are loose, hollow-sounding or lifting at the edges.
• There’s staining, soft plasterboard or a musty smell around the shower.
• The shower was tiled before waterproofing was expected and has no tanking behind it.
• The tray has dropped or the enclosure flexes underfoot.

In those cases, expert guidance on tiled showers suggests the substrate needs a professional assessment, because no regrout will survive a wall that moves or traps water.

At that point the cost question changes. A full bathroom renovation with us is priced at £2,500 to £4,000 as a one-off, and that is worth comparing against several rounds of patching an ageing enclosure. If you are weighing a new shower layout, our guides on bath to shower conversion costs and timelines and what a walk-in shower costs will help you set a budget.

Preventing cracks in the new grout

Whether you repair or replace, a few habits make the new work last:

• Ventilate. Run the extractor fan during and after showers, and leave it on for a while.
• Wipe down. A quick squeegee of the walls reduces the time water sits on the joints.
• Check the silicone yearly. Renew it when it blackens or peels away, before water finds the gap.
• Use neutral cleaners. Harsh acidic products can eat into cementitious grout.
• Deal with small cracks early. A single crack costs a fraction of what damp behind the tile does.

Our tiling and shower work in Cardiff

If your shower grout is cracking and you’d like someone to look at the whole picture, we can help. Our team covers tiling services, plumbing, and full bathroom and wet room work across Cardiff and the Vale of Glamorgan, with fixed pricing and no showroom markup. You can see how a complete refit works on our bathroom renovation page, or if you suspect the water is coming from pipework, see our plumbing services.

FAQ

Can you just grout over cracked grout?

No. New grout won’t bond to the old layer and will crack again quickly. The old grout needs raking out to at least 2-3mm deep, and the joint vacuumed clean before you refill it.

How long does a shower regrout take?

One source on shower regrouting suggests a professional team can usually finish a standard shower in a single day, though that guide is Australian. Add time for the grout and silicone to cure before you shower again, and follow the product instructions.

Why is my new shower grout already cracking?

The usual cause is a poor mix, with too much water added. Another is grout in a corner or tray junction that should have been flexible silicone. If it is widespread, the walls or adhesive may also be at fault.

Is it expensive to regrout a shower?

Not compared with the damage it prevents. A UK cost guide gives £150 to £400 for small patch repairs and £300 to £800 for a full enclosure, often before 20% VAT. Your quote will depend on size, tile type and the condition behind the tiles.

Should I call a plumber for cracked shower grout?

Usually a tiler or bathroom fitter is the right call, as grout and tiles aren’t plumbing. Call a plumber if you suspect a leaking pipe, valve or waste, for instance if a ceiling below is stained or a wall stays damp when the shower is unused.

Sources

• Bathroom Tanking and Waterproofing: BS 5385 Requirements
• Tile Movement Joints: BS 5385 Spacing Guide
• Tile Grout Repair Cost (2026 UK Guide)
• Why Does Grout Crack? What to Do (Angi)
• Tiled showers (Home Inspector)
• How to Regrout a Shower (Family Handyman)
• New Build Snagging Costs (Property Passport UK)
• Cracked Grout in a Shower: Causes and What to Do
• Cost to Regrout a Bathroom
• How to Regrout a Shower: A Complete Guide

Recommended

• Turn £1,200–£7,000 into an Itemised Walk In Shower Quote for UK Homes
• £500–£2,500+ UK Bath to Shower Conversion: Timeline & Hiring Checklist
• Shower Niche Ideas for UK Homes: 8 Styles and How to Stop Leaks