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You notice it while you're cleaning the shower recess: the silicone along the base has gone patchy, maybe a little black around the edges, and it doesn't quite hug the tile the way it used to. It's easy to tell yourself it's just cosmetic. The trouble is, bathroom sealant isn't decoration. It's the last line of defence between your daily showers and the timber, plasterboard and structural framing hiding behind the tiles.
Once that seal fails, water has a way in and no easy way back out. On the Gold Coast, where humidity keeps bathrooms damp for longer between uses, a compromised seal can turn into a mould and rot problem faster than homeowners expect.
This guide walks through the warning signs that your bathroom needs resealing, what actually causes the seal to break down, and how to decide whether it's a weekend DIY job or one for a licensed professional.
What Does "Resealing" Actually Mean?
Resealing is the process of removing old, failed silicone sealant from the joints in your bathroom, typically where the shower base meets the tiles, around the bath, along skirting joints, and around waste outlets, and replacing it with fresh sealant. It's different from waterproofing membrane repair, which sits underneath the tiles and is a much bigger, more invasive job.
Most homes only ever need the visible silicone joints redone. A full waterproofing membrane repair is usually only necessary once water has already been getting through for a long time.
Signs Your Bathroom Needs Resealing
1. Cracking, Peeling or Shrinking Silicone
New silicone sits flush against the tile and stays flexible. As it ages, it can crack, shrink away from the surface, or start peeling at the edges. Once you can see a gap, however small, water is getting behind it every time you shower.
2. Black or Pink Mould Along the Joints
Discolouration in the sealant itself, particularly black or pink mould, is one of the clearest signs the seal has failed. Mould needs moisture to grow, and if it's established inside the silicone joint, water has already been sitting there for a while.
3. A Musty Smell That Won't Go Away
If your bathroom smells damp even after cleaning, the odour is often coming from trapped moisture behind the tiles or under the shower base, not from anything on the surface. Sealant failure is one of the most common causes.
4. Water Pooling Outside the Shower Recess
If water is escaping past the shower screen or hob and pooling on the bathroom floor after every shower, the seal along the base of the recess may no longer be doing its job.
5. Soft or Spongy Grout
Grout that feels soft, crumbles when pressed, or has visible gaps is often a sign moisture has been getting underneath it. This usually shows up alongside failing silicone rather than on its own.
6. Discolouration on the Ceiling Below (Multi-Storey Homes)
For homes with a bathroom above another level, a stained or bubbling ceiling underneath is a strong indicator that water has been finding its way through the floor waterproofing, not just the wall joints.
What Causes Bathroom Seals to Fail?
- Age: Standard silicone sealant has a usable life of roughly five to ten years, depending on quality and how much moisture the bathroom sees day to day.
- Constant Humidity: Gold Coast bathrooms, especially those without good exhaust ventilation, stay damp for longer after each use, which accelerates mould growth and sealant breakdown.
- Poor Original Installation: Sealant applied over dirty, greasy or wet surfaces never bonds properly and tends to fail early.
- Movement in the Building: Minor settling, particularly in newer builds, can stress the joint and cause the sealant to crack even if it was installed correctly.
- Harsh Cleaning Products: Bleach-heavy cleaners and abrasive scrubbing break down silicone faster than gentler alternatives.
- Never Being Replaced: Many homeowners have never resealed a bathroom because it wasn't something they knew to check. Original sealant from a 15 or 20-year-old build is well past its working life even if it looks intact from a distance.
DIY Resealing: What's Involved
For a straightforward silicone joint with no underlying water damage, resealing is a manageable weekend job for a confident DIYer.
- Remove the old silicone completely. A sealant removal tool or sharp utility knife works better than trying to pull it out by hand. Any leftover residue will stop new silicone from bonding.
- Clean and dry the joint thoroughly. Use isopropyl alcohol or a dedicated silicone cleaner to remove mould, soap residue and grease. The joint needs to be completely dry before you apply new sealant.
- Mask the edges with painter's tape for a clean, straight line.
- Apply a bathroom-grade silicone (look for one with mould inhibitors) in a continuous bead.
- Tool the bead smoothly with a silicone finishing tool or a wet finger, then remove the tape immediately.
- Avoid water contact for at least 24 hours while the silicone cures.
DIY resealing works well when the problem is limited to surface silicone and the substrate underneath is dry and undamaged.
When DIY Isn't Enough
Resealing only fixes what you can see. If moisture has already travelled past the silicone and into the substrate, replacing the surface bead does nothing for the damage underneath, and the new seal will often fail again within months because it's covering up a bigger problem.
Call a licensed plumber or waterproofing professional if you notice:
- Soft, spongy or bouncy flooring near the shower or bath
- Persistent mould that returns within weeks of cleaning, even after resealing
- Visible staining or bubbling paint on a ceiling below the bathroom
- A musty smell that doesn't improve after the silicone is replaced
- Tiles that sound hollow when tapped, which can indicate the adhesive underneath has failed
- Any sign the waterproofing membrane itself may be compromised, not just the surface silicone
A professional can assess whether the issue is cosmetic or structural, and in cases where the membrane has failed, coordinate the right repair rather than leaving you to reseal the same joint every year.
How to Prevent Bathroom Seals From Failing Early
- Run the exhaust fan during and for at least 20 minutes after every shower
- Wipe down tiles and glass after use to reduce standing moisture
- Avoid bleach-based cleaners directly on silicone joints
- Address small cracks or gaps as soon as you notice them, rather than waiting
- Have your bathroom sealant checked every few years, particularly in older homes
- Ensure your bathroom has adequate ventilation, especially in humid, coastal conditions
Protect Your Home From Hidden Water Damage
A failing bathroom seal rarely looks urgent. It's a hairline gap in the silicone, a faint smell, a bit of discolouration you keep meaning to clean. But behind that small, easy-to-ignore sign is a pathway for water into parts of your home that are expensive and disruptive to repair once damage sets in.
If you've spotted any of the warning signs above and you're not sure whether it's a simple silicone refresh or something more serious, it's worth having it looked at before deciding. Coastal Plumbing Professionals can assess your bathroom, confirm whether the waterproofing membrane is intact, and recommend the right fix for your situation.
Contact Coastal Plumbing Professionals today to book a bathroom inspection.
Frequently Asked Questions
How often should a bathroom be resealed?
Most bathrooms need resealing every five to ten years, though homes with poor ventilation or heavy daily use may need it sooner.
Can I reseal over old silicone?
No. New silicone will not bond properly to old sealant, dirt or soap residue. The old bead needs to be fully removed before resealing.
Does a musty smell always mean I need to reseal?
Not always, but it's one of the most common causes. If resealing doesn't resolve the smell within a week or two, the issue may be in the waterproofing membrane rather than the surface silicone.
Is resealing the same as waterproofing?
No. Resealing replaces the visible silicone joints. Waterproofing refers to the membrane beneath the tiles, which is a separate and more involved repair if it has failed.
Can I shower right after resealing?
Most bathroom silicones need at least 24 hours to cure fully before contact with water. Check the product instructions, as cure times vary.
Resources
- Waterproofing | Queensland Building and Construction Commission
- AS 3740 Waterproofing of Domestic Wet Areas | Standards Australia
- Mould and your health | Queensland Health
