Since 15 January 2026, you can build a small standalone dwelling — a granny flat — on your property without a building consent, and in many cases without a resource consent either. It is the most useful change to residential development rules in years, and it has been widely reported as a free pass.
It isn't a free pass. It's a narrow door. Walk through it properly and you've saved yourself months and thousands of dollars. Miss the frame by a fraction and you're back in the ordinary consenting queue, usually having already spent money.
I've spent forty years and a hundred-odd deals working out whether a site stacks up before committing to it, so let me give you the version I'd give a client: what changed, where the boundaries actually are, and where the opportunity genuinely sits.
What changed
Two separate things came into force on the same day, and it's worth understanding that they are two things, because people routinely conflate them.
The first is a building consent exemption for small standalone dwellings, under the Building and Construction (Small Stand-alone Dwellings) Amendment Act 2025. If your granny flat qualifies, you don't need a building consent.
The second is the National Environmental Standards for Detached Minor Residential Units (NES-DMRU), which is the planning side. If your project meets the permitted activity standards, you don't need a resource consent.
These operate independently. You can qualify for one and not the other. Assuming that clearing one clears both is the single most common mistake I'm seeing.
The government's own estimate is that the two exemptions together save somewhere up to $5,650 in direct costs on a granny flat build. That's real money, and it's before you count the time.
The shape of a qualifying dwelling
The exemption is deliberately tight. In broad terms, the dwelling must be:
- New, standalone and single-storey, up to 70m²
- Simple in construction — lightweight roof and framing, straightforward plumbing and drainage
- Fully compliant with the Building Code in every respect, exemption or not
- Built or supervised by licensed practitioners — LBPs, and licensed plumbers, drainlayers, gasfitters and electrical workers, because this is restricted building work
It can be fully self-contained with a kitchen and bathroom. And importantly, it does not have to house a family member. It can be rented, used for extended family, or used as guest accommodation. That's what makes this an investment proposition rather than a lifestyle one.
There is still a process, even without a consent:
- You must obtain a Project Information Memorandum (PIM) from your council before any building work starts.
- On completion, you notify the council and supply the required documentation — final plans, Records of Work, certificates of compliance — within 20 working days.
And there are no routine council inspections along the way. Read that twice, because it matters more than anything else in this article. Compliance responsibility sits squarely with the designer, the builder and the owner.
Where the traps are
Development contributions still apply. This is the one that catches people financially. Most councils still charge development contributions for an additional dwelling, to fund the extra load on pipes, roads and community infrastructure. Nothing in the exemption removes that. The amount, the timing and the trigger vary by council and by zone, and it typically surfaces at the PIM stage. If you haven't put a number in your feasibility for it, your feasibility is wrong.
No inspections cuts both ways. Without a council inspection regime, nobody is independently checking the work as it goes up. That's the efficiency gain and it's the risk. If it's built badly, the problem doesn't show up at a failed inspection — it shows up years later at sale, at insurance, or in a leak. Your protection is the quality of the people you engage, so engage properly licensed, properly experienced ones and don't shop purely on price.
Your council may be more permissive than the national standard. Local rules can be more flexible than the NES-DMRU, not just less. Check both. Some sites have more room than the headlines suggest.
Site reality still governs. Terrain, wind zone, ground conditions, natural hazards, service connections. National rules simplify the paperwork; they don't flatten your section or move your sewer.
Where the opportunity actually sits
Strip the noise away and here's the developer's read.
The value of this change is not that granny flats became cheap. It's that they became fast and predictable. In development, certainty of timeline is worth as much as savings, sometimes more — it's what lets you fix a construction programme, hold finance costs down, and get to income sooner. Removing a consent process removes the single most variable item in a small build's timeline.
That advantage is only captured by designing inside the exemption from day one. The people who will do well out of these rules are the ones who set the constraints first — 70m², single storey, simple lightweight construction, standard services — and design to them. The people who will be disappointed are the ones who design what they want and then try to retrofit compliance. Step outside the boundaries anywhere and the consents come straight back, and you've lost the entire benefit while keeping all the cost.
The other place the opportunity concentrates is in well-located land that already has good bones: an existing dwelling, established services, spare rear yard, sensible access. Adding a self-contained unit to that kind of site produces yield without land cost, which is the most efficient dollar in residential development. This is now materially easier to execute than it was in 2025.
How I'd run the numbers
If someone brought me a site tomorrow, this is the order I'd work in:
- Confirm the site qualifies — zone, NES-DMRU permitted activity standards, and whether a compliant 70m² footprint physically fits with access and services.
- Price the whole cost, not the build cost — construction, design, services and connections, development contributions, PIM, professional fees, finance costs across the programme.
- Establish the income or value uplift — market rent for a self-contained unit in that location, or the valuation gain on the property as a two-dwelling site.
- Run the sensitivity — what happens if the build runs 20% over, or sits vacant for three months, or rates and insurance land higher than assumed. If the deal only works on best-case inputs, it isn't a deal.
- Then decide. Not before.
That's not complicated. It's just disciplined, and discipline is what separates the deals that work from the ones that look like they should have.
The short version
The 2026 rules are a genuine improvement and a genuine opportunity. They reward preparation and punish improvisation. Design inside the exemption, budget for the costs that didn't go away, engage people who know what they're doing, and get a PIM before you lift a hammer.
Do that and you've added a dwelling to your land faster and cheaper than at any point in recent memory. Do it loosely and you'll discover the exemption's edges the expensive way.