DIY bathroom renovation: what you can do yourself, and what you can't

You can do more of a bathroom yourself than people think, and less than YouTube suggests. Strip-out (after an asbestos test in a pre-2000 home), painting, tiling, fitting accessories and even the waterproof membrane are not licensed work in New Zealand. Plumbing is: the PGDB says homeowners cannot fix or unfix any pipe or plumbing fixture, so the toilet, vanity, shower and waste are a licensed plumber's job. Electrical work, including a fan or heated towel rail, is for a registered electrician.

Which jobs can a homeowner legally do?

Why can't I do my own bathroom plumbing?

Because sanitary plumbing in New Zealand is restricted to people authorised under the Plumbers, Gasfitters, and Drainlayers Act 2006. The PGDB's advice for consumers is plain about it: you can install appliances such as dishwashers and washing machines, and replace or repair taps, ball cocks and plugs, but you cannot do any work involved in fixing or unfixing any pipe, plumbing fixture or appliance. Pulling out a toilet or a vanity basin counts.

It also matters for consent. The Schedule 1 clause 35 exemption that lets you change bathroom plumbing without consent sits in Part 2 of Schedule 1, which only covers work done by an authorised person. DIY plumbing loses the exemption as well as breaking the plumbing rules. Our licensing guide shows how to check a plumber on the register.

What about electrical work in a bathroom?

Treat it as an electrician's job. The Electricity (Safety) Regulations 2010 contain a narrow homeowner exemption, with a code of practice behind it (NZECP 51, Homeowner/Occupier's Electrical Wiring Work in Domestic Installations), and new wiring done under it has to be tested and certified by an inspector before it is connected. A bathroom is the worst room to use it in, with water, a fan, often a heated towel rail and a heater. A registered electrician gives you a certificate of compliance, which is what an insurer or a buyer will ask for (EWRB).

Should you waterproof and tile it yourself?

You legally can, and a careful person with the right membrane system can do it well. It is also where most DIY bathrooms go wrong, because the membrane is invisible once tiled and the failures show up a year or two later in the framing. If you do it, use one manufacturer's system end to end, follow its instructions on coats, cure times and corner detailing, and photograph every stage before tiling. Those photos and the product data are the records you should keep for exempt work, and the first thing a buyer's builder will ask about.

How much can DIY actually save?

Less than the labour line suggests. Superior Renovations puts labour at 40–50% of a mid-range bathroom, but part of that is the plumber and the electrician, which you have to pay for either way. The realistic savings are in strip-out, painting and, if you are good at it, tiling. The common middle path is to do the strip-out and painting yourself and have the trades, waterproofing and tiling done by people who do them every week. Tell whoever you hire before you start, so the programme fits.