Hiring a Bathroom Renovator in NZ: Full Guide

Hiring a Bathroom Renovator in NZ: Full Guide

The most expensive thing in a bathroom renovation is not the tiles or the vanity. It is the thing you cannot see. A bathroom that leaks behind the linings looks perfect on handover day and costs thousands two years later, and by then the person who built it may be long gone.

There is a second surprise, and it catches out organised homeowners who assume that no consent means no rules. Under section 17 of the Building Act 2004, all building work must comply with the Building Code whether or not a consent is needed. Exemption is not a quality exemption.

So the two questions worth settling before anyone lifts a tile are simple. Does this scope need a consent, and what is protecting the framing behind the wall?

How We Researched This Guide

We worked from the primary documents rather than from trade marketing. The consent position comes from the Building Act 2004 and from MBIE determination 2024/054, which considered two tiled showers in an existing dwelling. The Building Code requirements come from clause E3 Internal Moisture, read alongside the performance requirements that govern bathroom wall surfaces.

One thing genuinely surprised us. Councils and the determination do not say the same thing about tiled showers, and the reason is scope rather than disagreement. Some councils state flatly that a tiled wet area shower needs a consent. The determination found the work fell within clause 12 of Schedule 1 because the scope involved removing and replacing linings in an existing dwelling. The lesson is that the scope decides it, which is why we tell readers to ask their council rather than assume. The Building Code itself is set out in full on legislation.govt.nz.

The Quick Summary (60-Second Version)

If you read nothing else, read this.

• Consent depends on scope. A tiled shower in an existing dwelling may fall under a Schedule 1 exemption, but the Code still applies to it.
• Waterproofing is not Restricted Building Work, so an LBP is not mandatory for the membrane. A supplier-certified applicator and the paperwork matter more.
• Ask which Schedule 1 clause is being relied on, and why it fits your specific job.
• Get the membrane product details, the application record, and the pre-application moisture readings before the tiles go down.
• Plumbing under exemption 35 must be done by a person with current Board authorisation, and the fixture count cannot increase.
• Every LBP on restricted building work must give you a Record of Work. Ask for it before final payment.

What the Building Code Actually Requires in a Wet Area

The objective of clause E3 Internal Moisture is to safeguard people from the consequences of moisture accumulating inside a building. The functional requirement in E3.2(c) is that buildings be constructed to avoid the likelihood of damage to building elements caused by moisture.

Two performance requirements govern the walls. E3.3.4 requires wall surfaces adjacent to sanitary fixtures or appliances to be impervious and easily cleaned. E3.3.5 extends that to any surface likely to be splashed or contaminated during normal use.

Why the Tiles Are the Least Important Layer

A tiled shower system is not tiles. It is membrane attached to the timber framing, wet area membrane applied to the substrate, tiles adhered to that membrane, and the fixings, adhesives and grouting that hold it together. Every one of those layers is part of the compliance picture.

In determination 2024/054, two tiled showers were found to have failed clause E3 because cracking allowed water to penetrate behind the linings and into concealed building spaces. No consent was required for that work. The Code applied anyway, and the work did not meet it.

Consent, Exemptions and the Plumbing Rules

Exemption 35 covers alteration to existing sanitary plumbing, provided the total number of sanitary fixtures in the building does not increase and no specified system is modified. It does not cover water heater alterations. Any plumbing under it must be done by an authorised person, meaning a registered certifying plumber or drainlayer, someone on a provisional licence working under supervision, or a supervised trainee.

Where the plumbing could affect structural elements such as floor joists or wall framing, the work may need a consent regardless. Adding a shower, basin and toilet to an ensuite clearly needs one, because those fixtures are additional to what already exists.

Where there is doubt, the guidance is to seek a discretionary exemption or apply for a consent rather than risk applying an exemption incorrectly. That is a slower answer, but it is the one that holds up when you sell.

Waterproofing, Documentation and Who Is Accountable

Waterproofing is not Restricted Building Work, so an LBP is not generally mandatory for the membrane itself. That is not the comfort it sounds like. The practical substitute is a supplier-certified applicator and proper documentation, and using an experienced LBP, building surveyor or waterproofing professional remains sensible risk management, particularly where the work later needs explaining to a purchaser, an insurer or a lender.

Two documents should exist at the end. Each LBP who carries out restricted building work must provide a Certificate of Design or a Record of Work, which shows the work meets the Building Code. Separately, you should hold the installer's certification for the membrane system used, the product details, and the moisture readings taken before the finish went down.

The Owner-Builder Trap

Owner-builder exemptions do not cover electrical, gas, plumbing or drainage work unless the owner holds the appropriate licence. An owner-builder also cannot pay friends or family to do restricted building work under the exemption. It is a narrower option than most people assume.

Questions Worth Asking Before You Sign

Ask whether this scope needs a consent and who is confirming that with the council. If an exemption is being relied on, ask which clause of Schedule 1 and why it fits. Ask who is applying the membrane and whether they are certified by the supplier. Ask who is doing the plumbing and what their Board authorisation is. Ask whether an LBP will be involved and whether you will receive a Record of Work.

Then ask the practical ones. What is the sequence, and how long will the bathroom be unusable? What happens if a leak appears in two years, what is the written warranty, and does it cover the membrane?

Questions You Might Have

Do I need a building consent for a new tiled shower?

It depends on the scope, and councils do not all read it the same way. Some state that a tiled wet area shower needs a consent because it involves carpentry and membrane work. MBIE determination 2024/054 found the opposite for an existing dwelling where linings were removed and replaced. Ask your council before work starts rather than assuming either way.

Is waterproofing restricted building work?

No. Waterproofing is not Restricted Building Work, so an LBP is not generally mandatory for the membrane itself. The practical substitute is a supplier-certified applicator, product documentation, and a record of the moisture readings taken before the finish went down. Using an experienced LBP or building surveyor is still sensible risk management.

Can my builder do the plumbing as part of the job?

Not unless they hold the appropriate registration. Plumbing under exemption 35 must be carried out by an authorised person with current authorisation from the Plumbers, Gasfitters and Drainlayers Board. A builder who is not registered cannot legally do that work, even as part of a larger renovation contract.

What if the work leaks two years later?

Your rights come from the Consumer Guarantees Act, not just the warranty wording. Give the renovator a chance to fix it first, and put the request in writing. If they refuse or do not succeed within a reasonable time, you can have it remedied elsewhere and recover reasonable costs, or cancel the contract. Claims up to $60,000 go to the Disputes Tribunal.

What should I hold onto when the job finishes?

Keep the Record of Work from each LBP, the membrane certification and product details, your written quote and any signed variations, and photographs of the area before work started. That paperwork is what makes a future sale, insurance claim or leak enquiry answerable. It costs nothing to ask for and it outlives the renovator's interest in the job.

What Matters Most

A bathroom renovation is unusual because the failure is invisible. A leaking shower looks perfect for years, and by the time you notice, the evidence of how it was built is behind the tiles.

That is why the consent question and the membrane question matter more than the tile choice. Settle both deliberately, in writing, before anyone starts. Ask which exemption is being relied on, and get your council's view rather than the renovator's assurance.

Then hold onto the paperwork. The Record of Work, the membrane certification and the moisture readings are the things that protect you long after the renovator has moved on to the next job.