Black spots in the corners. A brown stain on the ceiling below. Silicone that lifts off in one long strip the moment you touch it. If that sounds like your bathroom, a shower reseal is probably your first thought, and it might be exactly the right fix. Or it might be a wasted weekend.
Here’s why. Most shower leaks trace back to one of three layers: the silicone sealant, the cement-based grout, or the waterproofing system hidden under the tiles. A shower reseal addresses failed surface sealant. It won’t fix damaged grout, plumbing faults or a failed waterproofing system beneath the tiles. This guide calls the three layers the 3-Layer Shower Failure Model. It shows you how to work out what’s going on, how to do the job yourself if silicone is the culprit, what regrouting and resealing tend to cost around Australia in 2026, and when to bring in a qualified tradie.
What is shower sealing, and what does a shower reseal actually fix?
In everyday bathroom terms, shower sealing usually means applying silicone or another suitable sealant around joints and junctions that need a flexible, water-resistant seal. A shower reseal involves removing failed silicone from the relevant joints and applying fresh wet-area sealant to help stop water escaping through those surface junctions. It addresses sealant failure only. It can’t repair a damaged waterproofing system under the tiles.
| Layer | What it is | Typical failure sign | Usual fix |
|---|---|---|---|
| 1. Sealant | Silicone in corners, hobs and joins | Cracked, peeling or black-spotted silicone | Reseal the joints (DIY-friendly) |
| 2. Grout | Cement-based tile joints | Crumbling, cracked or stained grout | Regrout and reseal |
| 3. Waterproofing system | Membrane and associated waterproofing under the tiles | Persistent damp, a stained ceiling below, swollen skirting | Assessment by a suitably qualified waterproofing professional |
Silicone is the layer you can see, so it gets blamed for everything. Plenty of people search for shower resealing when the real cause is tired grout, a leaking tap or something else entirely. Leaks can also start at a screen seal, waste connection, mixer or tap penetration, cracked tile, movement joint or a pipe inside the wall. The checks later in this guide help you rule those in or out.
How do you know if your shower needs a reseal, regrout or new waterproofing?
Start with the joints, then the grout, then the walls and ceiling near the shower. Cracked or black silicone points to a reseal. Crumbling grout points to a regrout. Damp skirting or a stain on the ceiling below means moisture is escaping somewhere, possibly through the waterproofing system, and that needs proper assessment. Most showers give you a decent clue in about ten minutes.
The 10-minute shower checklist
- Silicone is cracked, gapped or spotted with black mould: likely Layer 1 (sealant)
- Grout is crumbling, sunken or discoloured: likely Layer 2 (grout)
- Tiles sound hollow when you tap them: could be poor adhesion or water damage, so get a closer look
- Skirting is damp, there’s a stain on the ceiling below, or the room smells musty: moisture is getting out somewhere, so get it assessed
- Mould returns within weeks of cleaning: could be ventilation, condensation or moisture behind the silicone, so keep watching it and get advice if it persists
- Water pools on the bathroom floor outside the shower: check the hob and the screen seal first
More than one line can apply, which is why many tradies quote a regrout and reseal shower job as a single visit.
Not sure which layer has failed? A qualified professional can assess it on site.
When is a reseal not enough? Red flags for a failed waterproofing system
A reseal isn’t enough once water has got behind the tiles. No shower reseal can stop water that’s already travelling through the wall or floor. The usual signs are a stained ceiling below, swollen skirting, lifting tiles and mould that keeps returning after cleaning and fresh silicone.
Waterproofing in wet areas is regulated in Australia. The National Construction Code sets the applicable wet-area requirements and provides compliance pathways that reference AS 3740. What’s required in a particular bathroom depends on things like the shower’s configuration (a hob, a step-down, a level threshold, enclosed or unenclosed), so there’s no handy rule of thumb to apply yourself.
Licensing also varies between states and territories. In Victoria, for example, waterproofing is recognised as a class of domestic building work. Check with your state or territory regulator (the VBA, the QBCC or NSW Fair Trading, for instance) and hire an appropriately licensed or registered waterproofing professional where required.
Stop and call a qualified tradie if:
- There’s a stain, bubbling paint or a soft patch on the ceiling below
- The wall or plasterboard around the shower is swollen, soft or crumbling
- Tiles are lifting or sound drummy
- Mould keeps returning even after a proper clean and fresh silicone
- Water is escaping and you can’t work out where from
- The leak is showing up in a neighbour’s unit
How to do a shower reseal, step by step (DIY)
A shower reseal is a job many confident DIYers can finish in an afternoon: remove the old silicone, clean and dry the joint, tape it off, apply a new bead of sanitary-grade silicone, tool it smooth, then leave it to cure. Plan for a full day so the joint can dry before and cure after.
Resealing shower joints properly is mostly about preparation. The silicone itself is the easy bit.
What you’ll need: a utility knife or scraper, silicone remover gel, mould cleaner, methylated spirits, rags, masking tape, a caulking gun, a sanitary-grade silicone suited to wet areas, a tooling tool (or a gloved finger dipped in soapy water) and disposable gloves.
- Cut out the old silicone. Slice along both edges of the bead, then peel it out. Scrape off what’s left. Silicone remover gel helps with stubborn residue.
- Clean the joint. Scrub away mould and soap scum, rinse well, then wipe over with methylated spirits so the new silicone has a clean surface to grip.
- Let it dry completely. This is where most DIY jobs go wrong. Give it several hours, or overnight, with the exhaust fan running or a small fan pointed at the joint.
- Check what’s underneath. Press on the grout and the wall beside the joint. If anything moves, crumbles or feels soft, stop. That’s a job for someone else.
- Tape both sides. Run masking tape along each side of the joint, leaving a gap of about 3 to 4 mm.
- Apply the bead. Cut the nozzle at 45 degrees, slightly narrower than the joint. Squeeze with steady pressure and press the silicone into the gap as you go.
- Tool it smooth. One firm pass is better than five fussy ones. Peel the tape away while the silicone is still wet, pulling it back on itself.
- Leave it to cure. Follow the manufacturer’s instructions on the tube. Around 24 hours is common before the joint gets wet.
Safety note: keep the bathroom ventilated and wear gloves. Cleaners and silicone can irritate skin and airways, and methylated spirits is flammable.
How to reseal a shower floor and hob
To reseal shower floor joints, work on the floor-to-wall join first, then the hob, then anywhere the screen frame meets tile. Keep silicone out of the floor waste itself so water can still drain. Some screen frames have small drainage gaps on purpose, so check the manufacturer’s instructions before sealing right around them.
Common shower reseal mistakes
- Using a product that isn’t made for wet areas, or one that isn’t compatible with the surfaces (natural stone and some metals can be fussy, so check the label)
- Sealing over mould or a damp joint
- Laying new silicone over old silicone
- Using silicone where grout belongs, or grout where the joint needs to flex
- Using the shower before the silicone has cured
Can you regrout and reseal a shower at the same time?
Yes, and it’s often the smarter way to do it. Regrout the tile joints first, let the grout cure, then apply silicone to the corners and other movement joints. That order gives you a tidy finish and stops silicone getting smeared over joints that should be grout. If the grout is still sound, a shower reseal on its own is usually enough.
Grout is rigid and fills the gaps between tiles. Silicone is flexible and handles corners, the hob and other places where surfaces meet or move. Use the wrong one in the wrong place and it cracks, which is why shower regrouting and sealing often gets quoted as one job.
What pushes regrout bathroom costs up or down
Size is the big one, then tile type (small mosaics mean far more grout lines), how much hard old grout has to come out, and whether you choose epoxy grout. Heavy mould or loose tiles add hours, and capital cities are generally dearer than regional areas. Shower regrouting cost is mostly labour, so a fair quote spells out grout removal, cleaning, new grout, silicone and clean-up.
Is it really the shower? Five home checks before you reseal
Before you book a shower reseal, confirm the water is actually coming from the shower. Damp walls and mould can also come from condensation, a leaking tap, a waste pipe or a failed waterproofing system. These five checks give you clues, not a diagnosis, but they can point you towards the right professional before you spend anything.
| Check | What to do | What it might tell you |
|---|---|---|
| Timing | Note when the damp shows up: only after showers, or all the time, including days the shower isn’t used | Damp only after showers points to the shower area. Constant damp may point to plumbing or a slow leak |
| Water meter | Turn off every tap and appliance, then watch the meter for 15 to 30 minutes | Unexpected meter movement can indicate a plumbing leak, so arrange a plumbing assessment rather than assuming the shower seal is the cause. No movement doesn’t rule out a small leak |
| Foil or tape | Stick a small square of foil or clear tape flat on the damp wall for 24 hours | Moisture patterns can hint at surface condensation versus moisture within the wall, but this isn’t a definitive test |
| Ventilation | Notice whether the exhaust fan works, the mirror stays fogged and the room takes hours to dry | Poor ventilation can cause mould and damp on its own, with no leak at all |
| Tap and look | Tap the tiles gently for hollow sounds, then inspect grout and silicone around the hob, drain and skirting | Hollow tiles or swelling mean something needs a closer look, but not necessarily a failed membrane |
Please don’t try to test for leaks by aiming water at one area for days or by blocking the drain and flooding the shower. If there’s already a leak, that can push more water into the wall. Formal testing is a job for a qualified professional, who may also use moisture meters or thermal imaging to find hidden dampness without breaking tiles.
What your results might mean
| Result | Possible cause | Sensible next step |
|---|---|---|
| Damp only after showers, silicone failing | Layer 1, sealant | Reseal the joints |
| Damp after showers, grout crumbling | Layer 2, grout | Regrout and reseal |
| Damp all the time, or unexpected meter movement | Possible plumbing leak | Arrange a plumbing assessment |
| Damp after showers, hollow tiles, ceiling stain below | Possible waterproofing failure | Get an on-site assessment from a suitably qualified professional |
| Poor ventilation, moisture mostly on the surface | Possible condensation | Improve ventilation, then clean and monitor |
Photograph the damp, date the photos and keep any quotes. They’ll help if you need to talk to your insurer, landlord or body corporate. Insurers often treat sudden leaks and slow seepage differently, so read your own policy. If you rent, report leaks to your landlord or agent rather than repairing them yourself. If you live in an apartment, check with the body corporate before any waterproofing work.
If your checks point to hidden moisture, a plumber or a suitably qualified waterproofing professional can confirm it without guesswork.
How long does a shower reseal last, and how do you make it last?
A well-installed silicone joint can last several years, but the lifespan varies with product quality, preparation, movement, ventilation and bathroom conditions. Inspect the joints annually rather than relying on a fixed replacement date. A well-prepared shower reseal on clean, dry joints tends to outlast a rushed one.
A few habits help:
- Run the exhaust fan during every shower and for 15 minutes or so afterwards
- Squeegee or wipe the walls and screen when you’re done
- Skip harsh acid cleaners on grout and silicone
- Do a five-minute check once a year, looking for gaps, lifting edges and black spots
In humid parts of Queensland, the Northern Territory and coastal New South Wales, mould comes back faster. In cooler southern states, weak ventilation is more often the culprit.
Beyond the shower: bathroom reseal for baths, vanities and basins
A bath moves slightly every time it fills, so the join between bath and wall needs a flexible sealant. Vanity splashbacks and basin edges fail the same way. If you’re set up to reseal showers anyway, a bathroom reseal of the bath and basin joins in the same session saves a second trip to the hardware shop.
FAQs
How often should I reseal my shower? There’s no fixed date. A well-installed silicone joint can last several years, but lifespan varies with product, preparation, movement, ventilation and cleaning habits. Check the joints once a year. If the silicone is cracked, peeling, gapped or has black spots that won’t wipe off, it’s time to replace it.
Can I reseal a shower without removing the old silicone? Generally no. New silicone doesn’t form a reliable bond to cured silicone. Remove the old sealant completely, scrape off the residue, clean the joint and let it dry before applying the new bead.
What’s the difference between regrouting and resealing? Regrouting replaces the rigid, cement-based material between tiles. Resealing replaces the flexible silicone in corners, hobs and other joints where surfaces meet or move. A shower may need both eventually, but they address different problems. When both are needed, it’s usual to regrout first and apply silicone once the grout has cured.
How much does shower regrouting cost in Australia? It varies a lot with the size of the shower, tile layout and grout condition. Recent Melbourne Airtasker data suggests single-shower regrout and reseal jobs commonly sit around $300 to $650, but those are customer-posted amounts, not fixed prices. Get two or three written quotes.
Why does mould keep coming back after I reseal? Several things can cause it: poor ventilation, condensation, soap residue, silicone applied over a damp or mouldy joint, moisture trapped behind the silicone, or a plumbing or waterproofing problem. If mould returns quickly after a proper clean and reseal, get the area assessed on site.
Does a shower reseal fix a leak? Only if the leak is coming through failed silicone. If the water is escaping through cracked grout, a plumbing fault or a failed waterproofing system, fresh silicone won’t stop it. Work through the five home checks first, and get a professional opinion if you’re unsure.
Final word
A shower reseal is a quick, affordable fix when silicone is the real problem, and a frustrating one when it isn’t. Work through the three layers, run the five checks and match the repair to whatever has actually failed. Anything pointing to moisture behind the tiles belongs with a suitably qualified professional, and an on-site assessment beats sealing over a leak.
Not sure what’s causing your leak? Contact Black Diamond Caulking for an on-site assessment and a written quote.