Sealing the gap between a shower screen and a tiled wall is one of the most common bathroom maintenance jobs in NZ homes — and it's well within most homeowners' DIY abilities. Using the correct sanitary-grade silicone sealant and taking the time to prepare the surface properly will give you a neat, watertight seal that lasts for years.
Why This Gap Matters
A shower screen sits against a tiled wall but can't be permanently bonded to it — the screen needs a small amount of flex to absorb movement and vibration. That gap, typically 3–6 mm wide, is the last line of defence against water getting behind your tiles and into the wall framing. In New Zealand, moisture ingress in wet areas is governed by NZ Building Code clause E3 (Internal Moisture), which requires wet areas to be waterproofed to prevent damage to the building structure. A failed or missing seal is one of the most common causes of hidden water damage in NZ bathrooms.
What You'll Need
- Sanitary silicone sealant (mould-resistant, suitable for wet areas)
- Silicone gun (standard caulking gun)
- Utility knife or silicone removal tool
- Methylated spirits or isopropyl alcohol
- Clean cloths or paper towels
- Masking tape
- Smoothing tool or a wetted finger
- Gloves
Choosing the Right Sealant
Always use a sanitary or bathroom-grade silicone labelled as mould-resistant. Standard acrylic gap filler is not suitable for wet areas — it will fail quickly and allow mould to grow. Look for products from trusted suppliers at Bunnings or Mitre 10. Brands like Sika offer wet-area silicones well suited to this application — see Sika NZ for product guidance. Match the colour to your grout or frame where possible (white, grey, and clear are the most common options).
Step-by-Step: How to Seal the Gap
1. Remove the Old Sealant
If there's existing silicone in the joint, it must come out completely before you apply new sealant — new silicone will not bond properly over old. Use a silicone removal tool or utility knife to cut and peel away the old material. Take care not to scratch the glass or tiles. Specialist silicone remover products can help soften stubborn residue.
2. Clean and Dry the Surface Thoroughly
This is the most critical step. Wipe down both the tile surface and the shower screen frame with methylated spirits or isopropyl alcohol to remove soap scum, grease, and any silicone residue. Allow the surfaces to dry completely — at least 30 minutes, longer in humid conditions. Any moisture or contamination will cause the new sealant to fail.
3. Apply Masking Tape
Run masking tape along both sides of the gap — one strip on the tile, one on the shower screen frame. This keeps your bead neat and protects the surrounding surfaces from smearing. Leave the gap itself exposed.
4. Cut the Nozzle and Load the Gun
Cut the sealant nozzle at a 45-degree angle to match the width of your gap (usually 3–5 mm). Load the cartridge into your caulking gun and do a small test bead on a piece of cardboard to get a feel for the flow.
5. Apply the Silicone Bead
Hold the gun at a consistent 45-degree angle and apply steady, even pressure as you draw the gun along the gap in one smooth pass. Try to complete each run in a single continuous motion — stopping and starting can leave lumps. Fill the gap fully without overfilling.
6. Smooth the Bead
Immediately after applying, smooth the bead with a wetted finger or a silicone smoothing tool, pressing it slightly into the gap to ensure good adhesion on both surfaces. Work quickly — silicone begins to skin over within minutes.
7. Remove the Tape and Allow to Cure
Peel the masking tape away carefully while the silicone is still wet, pulling it back at a low angle. Allow the sealant to cure fully before using the shower — check the manufacturer's instructions, but most sanitary silicones require 24–48 hours before exposure to water.
Colour Matching and Aesthetics
If your tiles are grouted in a specific colour, try to match your silicone as closely as possible. Many manufacturers offer a range of colours. A neat, colour-matched bead looks far more professional than a mismatched one.
How Often Should You Reseal?
In a regularly used shower, silicone seals typically last 3–7 years before they begin to crack, peel, or go mouldy. Inspect your shower seals annually as part of general home maintenance. BRANZ recommends regular inspection of wet-area seals as part of good building maintenance practice.
When to Call a Professional
While sealing a shower screen is DIY-friendly, there are situations where you should bring in a qualified waterproofer or tiler:
- If tiles are cracked or loose — water may already be behind the wall, and the underlying waterproofing membrane may be compromised.
- If you notice soft or spongy wall material — this suggests moisture damage to the substrate (often GIB Aqualine or similar wet-area board) that needs professional assessment.
- If the shower screen frame is loose or incorrectly installed — resealing won't fix a structural issue.
- If you're installing a new shower screen — the waterproofing behind the screen must comply with NZ Building Code clause E3, and in some cases a building consent may be required. Always check with your local council before starting significant bathroom work. The MBIE Building Performance website has guidance on what work requires consent.
For Healthy Homes compliance in rental properties, moisture control in bathrooms is also relevant — see Tenancy Services for more information.
You can find qualified local waterproofers and tilers on tradedirectory.co.nz to get the job done right.
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SiteWise
Licensed Building Practitioner (LBP)
