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That dark, discoloured, or cracked strip of silicone around your bath or shower might look like a cosmetic issue — something to address eventually, maybe. But deteriorated silicone sealant around bathroom fixtures is far more than an eyesore. It's an open pathway for water to enter the gap between the tile and the bath or shower, saturating the wall substrate and floor, creating the perfect conditions for mould growth, and over time causing serious structural damage to wall framing and subfloor materials.
The cost of fixing water damage behind bathroom tiles can be significant — $2,000, $5,000, or more depending on how long it's been allowed to progress. The cost of resealing a bath or shower yourself? About $15 in materials and a couple of hours of your time.
This guide walks you through removing old silicone and applying a clean, professional-looking new seal — correctly, so it lasts.
Signs You Need to Reseal
Inspect the silicone around your bath or shower for:
- Black spots or streaks — mould growing into or through the silicone. Mould penetration means the sealant integrity is compromised
- Cracks, gaps, or splits — often visible particularly at corners or wherever the silicone meets tiles
- Silicone that's pulling away from the tile or bath surface — losing adhesion is a clear sign of failure
- Discolouration — yellowing or brown-staining of what was once white silicone indicates age-related degradation
- A raised or bubbled surface — indicates water has already penetrated behind the silicone
Any of these signs warrants full removal and replacement — spot-patching over old, failing silicone almost never works long-term as the new silicone won't adhere properly to the contaminated surface.
What You'll Need
- Silicone remover cream (available at hardware stores — dissolves old silicone for easy removal)
- Stanley knife or dedicated silicone removal tool
- Plastic scraper (avoid metal on acrylic baths)
- Fine-grade silicone pulling/smoothing tool or a gloved wet finger
- Masking tape
- White spirit or methylated spirit for surface cleaning
- 100% silicone sealant in the appropriate colour (white or clear are most common)
- A caulking gun
Choosing the right silicone:
For bathrooms, use a product specifically labelled "sanitary silicone" or "mould-resistant silicone" with an antifungal formulation. These are designed to resist the humid conditions of Australian bathrooms far better than standard construction silicone.
For acrylic or fibreglass baths and shower bases, ensure the product is rated as safe for acrylic — standard silicone can chemically attack some plastics over time.
Step 1: Remove All Old Silicone
Apply silicone remover cream
to the old sealant and leave it for the product's recommended time (typically 30–60 minutes). The remover softens the silicone, making it much easier to cut and peel away cleanly.
Score along both edges
of the silicone bead with a sharp knife, cutting cleanly at the interface between silicone and tile, and between silicone and bath surface.
Peel and pull
— grasp an edge and peel along the bead length in long strips where possible. Use the plastic scraper to remove any remaining pieces.
Don't rush this step.
The most common reason a new silicone seal fails prematurely is because old silicone residue was left behind on the surface. The new silicone can only bond as well as the surface below it.
Step 2: Clean the Surface Thoroughly
After all visible silicone is removed, any remaining residue needs to be cleaned off.
- Apply more silicone remover and scrape again if needed
- Wipe down the entire area with white spirit (mineral turpentine) on a clean cloth — this dissolves any oil or residue the remover missed
- Allow to dry completely — apply methylated spirits as a final wipe for a completely clean, dry surface
- Wait at least 30 minutes before applying new silicone; the surface must be fully dry
Step 3: Tape for Clean Lines
Apply masking tape on both sides of where the new silicone will go — 2–3mm away from the intended line on each side. Press the tape firmly so silicone doesn't bleed under the edge.
This step makes the difference between a professional-looking result and a messy one. The tape gives you crisp, clean edges and makes it easy to shape the bead without worrying about spreading silicone onto tiles beyond the joint.
Step 4: Prepare and Load the Silicone
Cut the cartridge tip at a 45-degree angle, creating an opening slightly narrower than the joint you're filling. Load the cartridge into the caulking gun. If using a cartridge tube, ensure it's fully loaded and no air gaps exist at the nozzle end.
Tip for corners:
Do your long runs first (straight edges), then do the corners last. This gives you cleaner corner junctions.
Step 5: Apply the Silicone Bead
Hold the gun at a consistent 45-degree angle to the joint, with the nozzle touching the gap. Apply steady trigger pressure while moving the gun at a consistent pace along the joint in one continuous motion where possible.
The goal is a consistent bead of silicone that fills the gap and makes slight contact with both surfaces (the tile and the bath/shower).
Common mistake:
Applying too much silicone. A smaller, neatly smoothed bead is better than a thick excess bead that's difficult to tool properly.
Step 6: Tool and Smooth the Bead
While the silicone is wet (work within 5–10 minutes of application as silicone begins skinning over), smooth the bead with:
- A silicone tool — plastic tools shaped specifically for this give the most consistent concave profile
- A wet gloved finger — dip your finger in soapy water and draw it firmly along the bead in one smooth motion
The goal is a slightly concave bead that's firmly pushed into the joint on both sides. Remove any excess with a wet cloth immediately.
Step 7: Remove the Tape and Cure
Remove the masking tape before the silicone fully skins over — typically within 5 minutes of tooling. Pull the tape back at a 45-degree angle while the silicone is still slightly wet, to get a clean line.
Leave the silicone to cure fully before exposing it to water. Most sanitary silicones require 24 hours for surface cure and 72 hours for full waterproof cure. Check your product specifications.
When to Call a Gold Coast Plumber
Resealing a bath or shower is DIY-friendly. But call Coastal Plumbing Professionals if:
- You find softness in the wall when pressing tiles — indicates water has already penetrated the substrate; the wall needs drying out and potentially repairs before resealing
- Tiles are cracked or loose near the seal line — these need to be re-adhered before sealing
- Mould returns within weeks of applying new silicone — may indicate ongoing moisture ingress from elsewhere, such as a failing shower screen seal or grout
- You're resealing a commercial bathroom or a rental property and need a waterproofing warranty for compliance
- The shower base itself is cracked — this requires professional waterproof repair, not silicone sealing alone
Call 1300 590 085
for bathroom waterproofing and repairs throughout Gold Coast.
Final Thoughts
Resealing a bath or shower is a manageable DIY job that directly protects one of the most water-exposed areas of your Gold Coast home. The key to lasting results is thorough removal of old silicone, scrupulously clean and dry surfaces, and quality sanitary silicone applied in one confident pass.
Done correctly, a fresh silicone seal provides years of waterproof protection and dramatically reduces the risk of water damage inside your bathroom walls and floor. Coastal Plumbing Professionals can handle bathroom waterproofing and repairs for any situation beyond a straightforward reseal. Call 1300 590 085 or visit coastalplumbingprofessionals.com.
Frequently Asked Questions
How often should I reseal my bath or shower?
High-quality sanitary silicone in a well-ventilated bathroom typically lasts 5–10 years. In poorly ventilated bathrooms, or where movement in the structure is common, resealing every 3–5 years may be needed.
Can I apply new silicone over old silicone?
It's not recommended. New silicone bonds to clean, solid surfaces. Old silicone — even if it looks intact — has an aged, contaminated surface that won't hold the new sealant reliably. Full removal gives far better long-term results.
What's the difference between regular and sanitary silicone?
Regular (builder's) silicone may not contain antifungal additives and isn't formulated for the constant humidity of a bathroom environment. Sanitary silicone contains biocides to resist mould growth and is specifically designed for wet areas. Always use sanitary silicone in bathrooms.
My silicone has gone mouldy — can I clean it off or do I need to replace it?
If mould is only superficial (on the surface, not through the silicone), a diluted bleach solution or commercial mould cleaner may remove it temporarily. But if mould has penetrated the silicone itself (appearing as black threads throughout), the silicone needs to be replaced — you can't clean through the material.
How long after resealing before I can use the shower?
Follow the product instructions, but as a general rule: 24 hours minimum before any water contact, 72 hours for full waterproof cure. Using the shower too early can cause the sealant to lift or develop voids.
Resources
- Coastal Plumbing Professionals – Bathroom Repairs Gold Coast
- Australian Standard AS 3740 – Waterproofing of Domestic Wet Areas
- Queensland Building and Construction Commission
