Removing old silicone from a tiled shower corner is a satisfying DIY job — but it does take patience and the right approach. Done properly, you'll end up with a clean, mould-free surface ready for fresh sealant, which is essential for keeping your shower watertight and compliant with the NZ Building Code's requirements around wet area waterproofing (refer to MBIE Building Performance for guidance on wet area standards).
Why Removing Old Silicone Properly Matters
Silicone sealant in shower corners is a movement joint — it's designed to flex as the building moves and as tiles expand and contract. Over time, silicone can discolour, grow mould, or lose adhesion. Simply applying new silicone over old is a common mistake: the new layer won't bond properly and will fail quickly, potentially allowing water to penetrate behind tiles. Poor waterproofing in wet areas is one of the leading causes of costly water damage in NZ homes.
Tools and Materials You'll Need
- Silicone removal tool (plastic or stainless scraper — avoid steel blades on glazed tiles)
- Stanley knife or utility knife with a fresh blade
- Silicone remover chemical (available at Bunnings or Mitre 10 — look for products specifically labelled for silicone removal)
- Clean cloths or paper towels
- Isopropyl alcohol (IPA) or methylated spirits
- Painter's tape
- Replacement sanitary-grade silicone sealant (mould-resistant, suitable for wet areas)
- Safety glasses and gloves
Step-by-Step: Removing Silicone from a Shower Corner
1. Score Along Both Edges
Using a sharp utility knife, carefully score along the top and bottom edges of the silicone bead where it meets the tile surface. Hold the blade at a shallow angle to avoid scratching the tile glaze. Take your time — this step separates the silicone from the tile so it peels away more cleanly.
2. Apply Silicone Remover (Optional but Helpful)
For stubborn or thick beads, apply a chemical silicone remover and leave it to soak for the time specified on the product label (usually 30–60 minutes). This softens the silicone and makes mechanical removal much easier.
3. Pull Away the Bulk of the Silicone
Grip one end of the silicone bead with your fingers or pliers and pull it away in one long strip if possible. A plastic scraper or dedicated silicone removal tool helps lift any remaining chunks without scratching the tile surface.
4. Scrape Off Residue
Use your plastic scraper or the back edge of a utility knife blade to carefully scrape off any remaining silicone residue. Work in small sections and keep the blade angle low. Never use a metal scraper aggressively on glazed tiles — it can leave permanent scratches.
5. Clean the Surface Thoroughly
Wipe the joint area down with isopropyl alcohol or methylated spirits on a clean cloth. This removes any oily silicone residue and is a critical step — new silicone will not bond properly to a contaminated surface. Allow the area to dry completely (at least 30 minutes, longer in cooler or humid conditions).
6. Check for Mould Behind the Joint
Once the old silicone is removed, inspect the grout and tile edges for mould or damage. If you find black mould penetrating into the grout or substrate, treat it with a suitable mould killer before resealing. Persistent mould can indicate a deeper moisture problem worth investigating — BRANZ has useful resources on moisture management in NZ homes.
7. Apply Fresh Silicone
Mask both sides of the joint with painter's tape for a neat finish. Apply a sanitary-grade, mould-resistant silicone in a smooth, continuous bead. Tool the joint with a wet finger or silicone tool, then remove the tape immediately before the silicone skins over. Allow to cure fully (check the manufacturer's datasheet — typically 24 hours minimum before water exposure).
Choosing the Right Replacement Silicone
Always use a sanitary or bathroom-grade silicone with mould inhibitors for shower corners — standard construction silicone is not suitable for wet areas. Products from Sika are widely available in NZ and well-regarded for wet area applications. Check the product is rated for continuous water immersion and is compatible with your tile type.
Safety Notes
- Work in a well-ventilated space — silicone removers and solvents can produce fumes.
- Wear safety glasses and gloves when using chemical removers or sharp blades.
- Dispose of old silicone and chemical-soaked cloths responsibly. Check with your local council for hazardous waste disposal options.
- See WorkSafe NZ for general safe handling of chemical products.
When to Call a Professional
This is generally a manageable DIY task, but consider calling a qualified tiler or waterproofing specialist if:
- You find cracked, loose, or hollow-sounding tiles when you tap them — these may need re-laying.
- There is evidence of water damage, rot, or mould in the wall substrate behind the tiles.
- The shower is in a rental property and you need to ensure compliance with relevant tenancy and property maintenance obligations — check with Tenancy Services for current requirements.
- You're unsure whether the original waterproofing membrane is intact — a compromised membrane is a building consent issue and should be assessed by a professional.
A skilled local tiler can re-seal and re-grout a shower quickly and to a high standard. You can find qualified tilers in your area at tradedirectory.co.nz.
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