Installing a shower tray can be a satisfying DIY project — but in New Zealand, the rules around what you can and cannot do yourself are important to understand before you pick up a spanner. The short answer is: you may be able to do some of the preparation and fitting work yourself, but connecting the waste to the drainlaying system is restricted work that must be carried out by a licensed tradesperson. Getting this wrong can result in fines, failed inspections, and serious water damage.
What Work Is Legally Restricted?
Under the Plumbers, Gasfitters, and Drainlayers Act 2006, drainlaying work — which includes connecting a shower waste to the household drain — is restricted work. Only a licensed drainlayer or licensed plumber (who is also registered to do drainlaying) can legally carry out this connection. This applies whether you're in Auckland, Christchurch, or a small rural town.
If you do this work yourself and something goes wrong — a leak, a blocked drain, or a failed building inspection — you could face liability issues and your home insurance may not cover the damage. Always check with the Plumbers Gasfitters & Drainlayers Board if you're unsure what falls under restricted work.
What Can a Homeowner Do Themselves?
The good news is that a competent DIYer can legally handle quite a bit of the preparation and installation:
- Preparing the substrate — levelling the floor, laying a mortar bed, or installing a pre-formed shower tray base
- Setting the shower tray in position — placing and levelling the tray on adjustable feet or a mortar bed
- Waterproofing — applying a membrane system around the shower area (this is strongly recommended and may be required under NZ Building Code clause E3 for internal wet areas)
- Tiling around and up to the tray
- Fitting the waste grate and trap above the connection point (the trap itself must be correctly installed — confirm with your plumber where the handover point is)
However, the moment you're making a new connection into the existing drain or soil stack, you need a licensed professional.
Understanding the NZ Building Code Requirements
Shower installations must comply with the NZ Building Code, particularly:
- Clause E3 (Internal Moisture) — requires adequate waterproofing of wet areas to prevent moisture damage to the building structure
- Clause G12 (Water Supplies) and Clause G13 (Foul Water) — cover plumbing and drainage standards
Most shower tray replacements (like-for-like) won't require a building consent, but adding a new shower where one didn't exist before likely will. Always confirm with your local council before starting — Schedule 1 of the Building Act lists exemptions, but interpretations can vary by council.
BRANZ is an excellent resource for understanding best-practice waterproofing and wet area construction in NZ conditions.
Choosing the Right Shower Tray
NZ homes vary widely — from older villas with timber subfloors to modern concrete slab construction. Your choice of tray matters:
| Subfloor Type | Recommended Tray Option |
|---|---|
| Timber framed floor | Acrylic or fibreglass tray on adjustable feet |
| Concrete slab | Low-profile tiled wetroom or acrylic tray on mortar bed |
| Renovation (existing recess) | Pre-formed acrylic or stone resin tray |
Stone resin trays are heavier but very durable. Acrylic trays are lighter and easier to handle solo. Both are widely available at Bunnings, Mitre 10, and PlaceMakers.
Waterproofing — Don't Skip This Step
Waterproofing is one of the most critical parts of any shower installation. In NZ's variable climate, moisture getting into wall framing or subfloors can cause rot, mould, and structural damage surprisingly quickly. Products from Ardex, Mapei, and Sika are all well-regarded in the trade for wet area membranes. Follow the manufacturer's instructions carefully, paying particular attention to corners and the junction between the tray and wall lining.
Step-by-Step Overview for DIYers
- Plan and measure — confirm tray dimensions, waste outlet position, and fall to drain
- Check consent requirements with your local council
- Engage a licensed plumber/drainlayer early — have them assess the existing drain and agree on the scope split
- Prepare the substrate — level, solid, and free of flex
- Set the tray — adjust feet or lay mortar bed, check level in all directions
- Apply waterproofing membrane to walls and tray-to-wall junction
- Tile and grout as required
- Have the plumber return to make the final waste connection and sign off the work
Safety Note
Working in confined spaces under floors or in wall cavities carries risks. Be aware of existing services (electrical cables, water pipes) before cutting or drilling. If you encounter any electrical wiring near the wet area, stop and consult a registered electrician — electrical work in wet areas is restricted work that must be carried out by a registered electrician — check with the Electrical Workers Registration Board for details.
When to Call a Professional
Call a licensed plumber or drainlayer for:
- Any connection to the existing drain or soil stack
- Relocating the waste outlet position
- Installing a new shower where none existed before
- Any work you're unsure about
A qualified plumber can also issue a Certificate of Compliance for the plumbing and drainlaying work, which is important for insurance and future property sales. You can find licensed local plumbers on tradedirectory.co.nz.
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