In most cases, yes — replacing a shower drain cover (also called a drain grate or strainer) is a straightforward DIY task that doesn't require a licensed plumber. However, if the job involves disturbing the drain body, waste pipe connections, or waterproof membrane beneath the shower floor, you'll need to think carefully about what's involved — and possibly call in a professional.
What Counts as Restricted Plumbing Work in NZ?
Under the Plumbers, Gasfitters, and Drainlayers Act 2006, certain plumbing work is restricted and must be carried out by a licensed tradesperson. This includes connecting, altering, or repairing sanitary plumbing — essentially anything that involves the drain pipework itself.
Replacing just the cover/grate that sits on top of the drain is generally considered maintenance rather than plumbing work, so homeowners can do this themselves. But if you need to remove the drain body, adjust the waste pipe, or re-waterproof the shower floor, that work should be done by a licensed plumber.
If you're ever unsure, contact the PGDB or your local council for clarification before you start.
Replacing the Drain Cover: A DIY-Friendly Task
Most shower drain covers simply clip, screw, or press into place. Here's how to approach it:
What you'll need
- Flathead or Phillips screwdriver
- Replacement drain cover (matching size and style)
- Mild cleaning products
- Silicone sealant (if resealing around the cover)
Steps
- Remove the old cover — unscrew any retaining screws or use a flathead screwdriver to pop out a clip-in cover. Some covers twist off anti-clockwise.
- Clean the drain recess — remove hair, soap scum, and old sealant. A clean surface is essential for a good seal.
- Check the drain body — while the cover is off, inspect the drain body for cracks, rust, or damage. If anything looks wrong, stop and call a plumber.
- Fit the new cover — make sure it's the correct size. Drain covers are commonly available in 80 mm, 100 mm, and 115 mm sizes. Check your existing cover or measure the recess before buying.
- Reseal if needed — if there's a gap between the drain flange and the tile or liner, apply a small bead of neutral-cure silicone (not acetoxy/acidic silicone, which can damage some surfaces). Smooth with a wet finger and allow to cure fully before using the shower.
You can find suitable drain covers and silicone at Bunnings or Mitre 10.
Choosing the Right Replacement Cover
Not all drain covers are interchangeable. Consider:
| Factor | What to check |
|---|---|
| Size | Measure the existing cover or drain recess diameter |
| Material | Stainless steel is most durable in wet areas |
| Fixing type | Screw-in, clip-in, or twist-lock |
| Flow rate | Ensure the grate pattern allows adequate drainage |
| Tile thickness | Some covers have adjustable heights for tiled floors |
If your shower has a linear drain, the cover is usually a long slot-style grate that lifts out — these are even simpler to replace.
Resealing the Drain: What to Watch Out For
Applying fresh silicone around the drain cover is fine for a homeowner to do. However, if the waterproof membrane beneath the tiles has been compromised — for example, if water is leaking under the floor — this is a more serious issue.
Shower waterproofing in NZ must comply with NZ Building Code clause E3 (Internal Moisture), and any remedial waterproofing work on a shower is likely to require a building consent or at minimum should be assessed by a professional. Poor waterproofing is one of the leading causes of costly structural damage in NZ homes.
BRANZ provides excellent guidance on wet area waterproofing standards and best practice if you want to understand what's required.
Safety Note
Always ensure the shower is dry before working around the drain. If you're using silicone or cleaning products in a confined space, ventilate the bathroom well. Check the product safety data sheet for any chemicals you use — WorkSafe NZ has guidance on safe handling of hazardous substances.
When to Call a Professional
Call a licensed plumber if:
- The drain body itself is cracked, corroded, or loose
- Water is leaking beneath the shower floor or into the ceiling below
- You need to adjust or replace the waste pipe connection
- The waterproof membrane appears damaged or you're unsure of its condition
- You're renovating the shower and making structural or layout changes (this may also require a building consent — check with your local council)
For any work that touches the sanitary plumbing system, always use a tradesperson registered with the PGDB. You can find qualified local plumbers on tradedirectory.co.nz.
Sources & Further Reading
- Plumbers, Gasfitters and Drainlayers Board (PGDB) — licensing and restricted work
- MBIE Building Performance — building consents and the NZ Building Code
- BRANZ — wet area waterproofing guidance
- WorkSafe NZ — safe use of chemicals and silicone products
- Bunnings — drain covers, silicone, and tools
- Mitre 10 — plumbing supplies and hardware
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