Do you need a building consent?

Most building work in New Zealand needs a building consent before you start. Schedule 1 of the Building Act 2004 is the list of exceptions, the smaller, lower-risk jobs the government has decided a council does not need to sign off first. A garden shed, a low deck, a standard fence, a like-for-like repair. That is what this tool checks against.

Here is the part people miss. Exempt means the council does not check it before you build. It does not mean the rules stop applying. Exempt work still has to meet the Building Code, the same technical standard as consented work. If your exempt deck is unsafe, it is still your problem, and still illegal. The council just was not there to catch it on the way through.

There is a second layer too. Building consent and resource consent are different things. Your project can be exempt from a building consent and still need a resource consent under your district plan, for height, for how close it sits to the boundary, or for how much of the section it covers. One green light is not both.

The detached-building exemption is the one people ask about most, usually phrased as "how big a sleepout can I put up without a consent". The honest answer has conditions, and they matter.

A single-storey detached building can be exempt up to 30 sqm of floor area. But the size band changes who has to be involved. Up to 10 sqm you can generally do it yourself (Schedule 1 exemption 3). Between 10 and 30 sqm there are two exempt routes: a Licensed Building Practitioner carries out or supervises the design and construction (exemption 3B), or the building is made of lightweight material to a manufacturer's design, a kitset being the classic case (exemption 3A). Free-styling a 20 sqm sleepout yourself out of heavy timber fits neither route and needs a consent.

The hard limit is plumbing. The exemption does not cover buildings with sanitary facilities, meaning a bathroom, toilet, shower or kitchen. Put any of those in and it needs a consent, no matter how small it is. So a 25 sqm sleepout with a bed and no wet areas can be exempt with an LBP. Add an ensuite and a kitchenette and it is a consent job. Over 30 sqm, or more than one storey, is always a consent. If sleeping accommodation is involved, smoke alarms are required.

It is tempting to read "no consent needed" as "no rules, crack on". That reading gets people into expensive trouble, so it is worth being blunt about it.

When you build exempt work, you take on the responsibility the council would otherwise carry. You are the one certifying, in effect, that it meets the Building Code. If it does not, there is no consent and no code compliance certificate standing behind it. That gap follows the house. A buyer's lawyer finds it, a bank asks about it, an insurer questions it after a claim. The saved consent fee looks small against a stalled sale years later.

The government even suggests you formally tell your council about completed exempt work and give them the drawings and photos, so there is a record. Worth doing. Just know that the council filing your paperwork is not the council approving the work. The buck still stops with you.

Skipping a consent you actually needed is an offence under the Building Act 2004. The maximum fine is $200,000, with a further fine of up to $10,000 for every day the offence continues. Most people never see the top of that, but the number tells you how seriously it is taken.

The bigger cost is usually the cleanup. To legalise unconsented work you apply to the council for a certificate of acceptance. It is the retrospective cousin of a code compliance certificate, and it is deliberately weaker, because the council can only vouch for what it can still inspect. Once the work is closed up behind linings and cladding, a lot of it cannot be checked, so the certificate covers less. If the council will not grant one, you get a notice to fix, which can mean opening the work back up or pulling it down.

Then there is selling. Unconsented work appears on the LIM report the buyer orders. It is one of the classic reasons a sale falls over or the price gets cut. A weekend saved at the start can cost you a settlement at the end.

This tool is built to point you the right way fast, but it cannot see your section, your district plan, or the fine print of your project. Some jobs sit right on a threshold, or combine two rules at once, and that is exactly when a two-minute phone call beats a guess.

• You are near a size, height or distance limit and not sure which side you land on.
• Your project mixes things, like a deck with a roof, or a shed with a sink.
• You are in a special zone, near a boundary, a heritage area, or a flood-prone or coastal site.
• You plan to sell within a few years and want it clean on the LIM.

Every council has a duty planner or a building helpdesk for exactly this. They would far rather answer a quick question up front than issue a notice to fix later. When in doubt, ring them, and use the official building.govt.nz page linked in the result as your starting point.