Bathroom Renovation NZ Guide 2026: Consent, Costs and Waterproofing

A bathroom renovation in New Zealand runs on three sets of rules. The building consent rules decide what paperwork you need. The licensing rules decide who may do each trade. Clause E3 of the Building Code decides how the room is waterproofed. Together they set your cost, your timeline and the documents you keep at the end.

This guide explains each set of rules in plain terms and gives 2026 prices from real Auckland jobs. The rules come from the Building Act 2004 and apply across New Zealand. Each council runs its own consent process, so the consent examples use Auckland Council’s guidance. If you live outside Auckland, check the detail with your own council.

Written by Nick McKelvie, Licensed Building Practitioner (BP1021390) and registered producer statement author for waterproofing (PSA127420). Nick has renovated Auckland bathrooms for 30 years.

Bathroom Renovation Rules in NZ: Quick Answers

Does a Bathroom Renovation Need Building Consent in NZ?

Some bathroom work needs a building consent and some does not. All bathroom work must meet the Building Code, with or without a consent. Schedule 1 of the Building Act lists the building work that is exempt from consent. Auckland Council gives bathroom examples on its kitchen and bathroom renovations page.

Bathroom work that usually does not need consent

• Replacing or moving a bath, basin, shower or toilet pan within an existing bathroom.
• Moving a toilet pan from a separate toilet into the bathroom next to it.
• Replacing existing sanitary plumbing and drainage, when an authorised plumber or drainlayer does the work.
• Replacing taps, ball valves and plugs.

An exemption removes the consent paperwork. It does not lower the standard. Exempt work must still comply with the Building Code, and the plumbing must still be done by an authorised person.

Bathroom work that needs consent

• Installing a tiled wet-area shower. Auckland Council classes this as critical building work that is not sanitary plumbing.
• Adding a shower, basin or toilet where none existed before, such as a new ensuite.
• Moving a vanity, bath or shower inside an apartment in a multi-level building, because new pipes may pass through a fire separation.
• Plumbing work that could weaken floor joists or wall framing.

The tiled shower rule catches most full renovations. Auckland Council lists a tiled wet-area shower as work that needs consent, because it is critical building work and not sanitary plumbing. Swapping an old shower for a new shower unit in the same bathroom is replacing a sanitary fixture, which the council lists as not needing consent. Councils read these rules differently, so check with yours before you choose. This one choice changes the cost, the timeline and the paperwork of the whole job.

Who applies for consent and how long it takes

The homeowner, or a designer acting for the homeowner, lodges the consent application with the council. The application includes plans and specifications that show the layout, the drainage and the waterproofing system.

The council has 20 working days to process a complete application. If the council asks for more information, the clock stops until you supply it (Building Performance, building consent process). During the build, a council inspector checks the work at the stages listed in the consent. When the work is finished, you apply for a code compliance certificate.

Alchemy does not lodge consents. You or your designer lodge the application, and Alchemy builds to the approved plans. Where the consent requires a producer statement for the waterproofing (a PS3), Nick issues it.

What happens if you skip consent

Work that needed a consent but went ahead without one is unconsented building work. The council can issue a notice to fix. To get the work recognised later, you apply for a certificate of acceptance. That process costs more than a consent and the council may need to see inside finished walls or floors. Buyers and insurers ask about unconsented work, so it can follow the house for years.

Who Is Allowed to Do the Work

New Zealand law splits a bathroom renovation between trades. Some work needs a licence. Some work a homeowner can do. Knowing the split tells you which quotes to trust.

Plumbing and drainage

Sanitary plumbing must be done by an authorised person. That means a certifying plumber, or a plumber working under a certifying plumber’s supervision. You can check any plumber on the Plumbers, Gasfitters and Drainlayers Board public register.

The Board does not count the replacement of taps, ball valves and plugs as sanitary plumbing. It also excludes connecting appliances such as a washing machine or dishwasher. A homeowner can do these jobs. Everything else in the pipework belongs to the plumber.

Electrical work

A homeowner who owns and lives in the house can do some electrical work without payment. Examples are replacing switches and light fittings, moving existing switches and outlets, and adding to a sub-circuit. A licensed electrical inspector must then test the work and connect it to the supply. Homeowners cannot do electrical work in a rental property (WorkSafe, doing your own electrical work).

Bathrooms carry extra wiring rules near the shower and bath, so most homeowners give the whole job to an electrician. The electrician issues an electrical certificate of compliance for the work. Keep it with the rest of the bathroom paperwork.

Carpentry and restricted building work

Restricted building work (RBW) is residential work that needs a building consent and affects the primary structure, weathertightness or certain fire safety design. Only a Licensed Building Practitioner can do or supervise it. Each LBP who does restricted building work on your home must give you a record of building work (Building Performance, restricted building work).

Interior waterproofing is not restricted building work on its own. A bathroom job becomes RBW when it changes the structure. A common example is removing or altering a load-bearing wall to enlarge the room. You can check any builder on the LBP public register at lbp.govt.nz.

Waterproofing

No separate licence exists for applying a waterproofing membrane. The protection comes from the consent process and the producer statement. A PS3 is a statement from the person who did the work that it matches the consented plans and the Building Code. Auckland Council accepts PS3s from registered producer statement authors. Ask who will sign the PS3 before you sign a contract.

Bathroom Waterproofing Rules: What Clause E3 Requires

Clause E3 of the Building Code covers internal moisture. It requires wet-area surfaces to be impervious and easy to clean, and it requires ventilation. It also covers overflow water and the conditions that lead to mould (Building Performance, E3 Internal moisture).

Two acceptable solutions show one way to comply with E3: E3/AS1 (2nd edition, amendment 7) and E3/AS2 (1st edition). Both took effect on 5 November 2020 and are the current versions in 2026.

Why tiles need a waterproofing membrane

Tiles and grout are not waterproof. Water passes through grout lines and soaks the floor and wall linings behind them. A waterproofing membrane under the tiles stops that water. In a tiled shower, the waterproofing membrane covers the shower floor, runs up the walls and seals into the waste outlet. Pipes that pass through the shower wall need a proprietary sealing system or a compatible sealant.

A failed waterproofing membrane stays hidden for months. By the time a stain shows on a ceiling or a skirting board swells, the framing behind the shower is often wet. This is why the waterproofing membrane matters more than the tile you choose.

Level-entry showers

A level-entry shower has no step, and you need a building consent to install one (Disability Support Services, level access showers). The shower floor still needs a fall so water runs to the waste, so it sits lower than the rest of the room. How the builder forms that fall depends on whether the floor is timber or a concrete slab, and the consent drawings show the method. Decide on a level-entry shower early, because it changes the floor work and the price.

Ventilation

Ventilation is part of E3 because damp air feeds mould. For rentals, the Healthy Homes standards set a clear number. A bathroom extractor fan installed after 1 July 2019 must have a 120 mm diameter or extract at least 25 litres per second, and it must vent outside (Tenancy Services, ventilation standard).

Owner-occupied homes are not bound by the Healthy Homes rule, but it is a sound target for any bathroom. Landlords with South Auckland properties can see how we plan rental bathroom renovations in South Auckland between tenancies. A fan that vents into the roof space moves the moisture problem into the ceiling.

What to ask for at the end of the job

• The name of the waterproofing membrane product and system.
• The PS3, if the consent required one.
• The written waterproofing guarantee. Alchemy guarantees its waterproofing for 15 years.
• The fan’s diameter and flow rate, if the house is or will be a rental.

What a Bathroom Renovation Costs in NZ in 2026

A bathroom renovation in Auckland costs between $15,000 and $65,000 or more with Alchemy in 2026. These are Alchemy’s published prices from Auckland jobs, not a national average. Prices in other regions differ with local labour rates and travel.

Alchemy publishes these ranges for its LBP-led bathroom renovations in Auckland and confirms each price in writing after a free site visit.

What moves the price

1. Layout changes. Moving the toilet or shower means new drainage. On a concrete slab, that means cutting the floor. On a raised timber floor, it means work under the house.
2. What the strip-out finds. Rotten floor framing under an old bathroom, or a shower that was never lined, adds framing work before the new bathroom goes in.
3. The shower type. A tiled wet-area shower needs a consent, which adds council fees, inspection time and the PS3. Replacing an existing shower with a new shower unit is fixture replacement and does not.
4. Fixtures and tiles. Tapware, a freestanding bath and large-format porcelain are the biggest lines on most quotes. Ceramic tile and a laminate vanity keep a job at the low end.
5. Room size. More floor and wall area means more waterproofing membrane, more tiling and more days on site.

Costs outside the builder’s quote

• Council consent and inspection fees for a tiled shower or new fixtures.
• Design or drafting fees, if the consent needs drawn plans.
• Asbestos testing, for homes built before 2000.
• An electrical inspection, if you do any of the electrical work yourself.

Ask each builder which of these their quote covers. A low quote that leaves out the consent and the waterproofing sign-off often ends up as the dearest job.

Asbestos in Older NZ Bathrooms

WorkSafe states that a home built before 1 January 2000 may contain asbestos (WorkSafe, asbestos in the home). Bathrooms are one of the likely places. Asbestos cement sheet, such as Fibrolite, was a common lining in wet areas. Asbestos can also sit in the backing of wall tiles and bath panels, in vinyl flooring and its adhesive, and in textured ceilings.

You cannot tell whether a material contains asbestos by looking at it. The only way to know is to test a sample. In a pre-2000 home, arrange the test before strip-out day so the job does not stop halfway.

Building Contracts and Your Legal Protections

Residential building work that costs $30,000 or more, including GST, must have a written contract. Before you sign, the builder must give you a disclosure statement and a consumer protection checklist. The builder must also give you both documents on request for a smaller job (Building Performance, contracts for your building project).

Implied warranties apply to all residential building work for up to 10 years, whatever the contract says and whatever the job costs. Under these warranties, the builder promises that:

• The work is done properly, competently and to the plans and specifications.
• The materials are suitable and, unless the contract says otherwise, new.
• The work complies with the Building Act and the Building Code.
• The work is done with reasonable care and skill, and finished within the agreed time.

A 12-month defects period also applies. If defects appear within 12 months of completion and you notify the builder, the builder must put them right (Building Performance, implied warranties and defects).

Documents to keep after a bathroom renovation

• The written contract, disclosure statement and checklist.
• The building consent and the code compliance certificate, if the job was consented.
• The record of building work from each LBP.
• The PS3 for the waterproofing.
• The electrical certificate of compliance.
• Product warranties for the waterproofing membrane, tapware, vanity and fan.

These papers matter when you sell. A buyer’s lawyer will ask for the consent and the code compliance certificate for a tiled shower.

How Long a Bathroom Renovation Takes

Most bathroom renovations take two to six weeks on site. A small bathroom or ensuite with no layout change sits at the short end. A complete renovation with new drainage, consent inspections and large-format tiles sits at the long end. Design, product ordering and the consent come before the start date, so plan for the consent’s 20 working days on top.

A full renovation on site usually runs in this order:

1. Strip-out to the framing.
2. New framing and floor work, where the strip-out shows it is needed.
3. Plumbing and electrical rough-in.
4. Wall and floor linings, with a council inspection if the job is consented.
5. The waterproofing membrane, with its own inspection on a consented shower.
6. Tiling, which takes three to five days.
7. Fit-off of the vanity, toilet, shower fittings, tapware and fan.
8. Final inspection and the application for the code compliance certificate.

Bathroom Renovation NZ: Frequently Asked Questions

Can I renovate my bathroom without a building consent?

Yes, if you replace or move fixtures within the same bathroom and do not install a tiled wet-area shower. Adding fixtures where none existed, or changing the structure, needs a consent. All the work must still meet the Building Code.

Is bathroom waterproofing a legal requirement in NZ?

Yes. Clause E3 of the Building Code requires wet-area surfaces to be impervious and easy to clean. In a tiled shower, a waterproofing membrane under the tiles meets this requirement, because tiles and grout alone let water through.

Can I do my own bathroom renovation in NZ?

Partly. You can remove old fittings, paint, and replace taps, ball valves and plugs. An authorised plumber must do the sanitary plumbing. You can do limited electrical work in your own home, but an inspector must test and connect it. Consented structural work needs a Licensed Building Practitioner.

How much does a small bathroom renovation cost in NZ?

A small bathroom or ensuite in the same layout costs $15,000 to $28,000 with Alchemy in Auckland in 2026. The price includes a new waterproofing membrane, tiling, vanity, shower, toilet, tapware, extractor fan and paint. Prices outside Auckland differ.

Do I need a written contract for a bathroom renovation?

Yes, if the work costs $30,000 or more, including GST. The builder must also give you a disclosure statement and a consumer protection checklist before you sign. The implied warranties protect you for up to 10 years whether or not you have a written contract.