Minor Dwellings and Tiny Homes in NZ: Rules, Cost and Whether They Stack Up

A minor dwelling and a granny flat are the same thing: a small, self-contained second home on the same section as the main house, built on foundations and, until this year, through the normal building consent process. A tiny home usually means something different in New Zealand: a small dwelling built on a trailer, sold as a way around the consenting system. The distinction matters, because the two paths lead to very different outcomes for quality, finance, insurance and resale.

At Ecotectural we build minor dwellings, not tiny homes on wheels, and we talk a lot of people through this exact choice. We recently completed our own offices this way: two separate 30 square metre buildings and a 10 square metre amenities block, linked by a covered deck, on our site at 79 Rowling Loop. Small standalone buildings are a build type we know well.

Since 15 January 2026, you can build a standalone, single-storey dwelling of up to 70 square metres on most residential and rural sites without a building consent, and in most cases without a resource consent either (MBIE granny flats exemption and the National Environmental Standards for Detached Minor Residential Units). The consent disappears, but a clear set of conditions replaces it.

The Government estimates the exemption saves around $5,650 in direct consent costs and up to 14 weeks of processing time (MBIE). Both Tasman District Council and Nelson City Council have published guidance on the new pathway, and Tasman discounts development contributions by up to 50 percent for a minor dwelling under 110 square metres with three or fewer bedrooms. The normal consent process still applies to anything larger, two-storey, or outside the exemption conditions.

Here is our honest view as builders: the exemption will produce some very good small homes and a lot of problems, and the difference will be entirely in who builds them. The Government has put backstops in place, licensed practitioners, records of work, council notification, but the piece that has gone is the independent check. Under a consent, the council inspects the work at each stage and signs it off at the end. Under the exemption, nobody above the builder signs anything off.

That changes where the risk sits. As Daryl Combes puts it: "The council is not signing it off, so the council carries no liability if something goes wrong. Whoever builds it is the only line of defence, and the owner is the one left with the problem." Companies chasing volume in this market have every incentive to take the shortcuts nobody will catch, and the defects that follow, missing fixings, poor flashings, skipped insulation, do not show up on move-in day. They show up in year three as a leak.

Our advice is simple: treat the exemption as a faster path, not a lower standard. Build to exactly what a consented build would have been, with a builder who documents everything and would happily have the work inspected. If a price on an exempt granny flat looks dramatically cheaper than a consented equivalent, the difference is coming out of the building. The same choose-your-builder-first logic applies here with double the weight, because the builder is the only quality gate left.

A tiny home on wheels is legally closer to a vehicle than a building, and that is exactly where the trouble starts. Because nobody has to sign it off against the Building Code, you are trusting the manufacturer completely, and the results are visible across the market: single-skin construction, minimal insulation, and condensation running down the walls by July. Many of them leak. If a dwelling is going to be lived in, the Building Code exists for good reasons, and a trailer under the floor does not change the physics.

The legal ground is also less solid than the sales pitch suggests. MBIE has made a series of determinations since 2016 on whether a tiny house on wheels is a vehicle or a building, and in every case it ruled the structure a building, with new national guidance published in January 2026 confirming that a tiny house occupied permanently must comply with the Building Code (MBIE). Then come the practical problems: banks will not take one as mortgage security, so finance is a personal loan at roughly two to three times home loan rates (Canstar); insurers may treat it as neither house nor caravan, leaving gaps in cover for permanent living (MoneyHub); resale is poor; and if it is permanently sited and connected to services, the council can treat it as an unconsented building.

If someone needs a genuinely mobile or temporary solution, a tiny home has a place. As a permanent home in Nelson Tasman winters, most of them are simply not up to it, and the same money put toward a real minor dwelling buys an asset instead of a liability.

It depends almost entirely on the specification, which is the honest answer few websites give. The structural shell of a small building is the cheap part. The expensive parts are the ones that do not shrink with the floor plan: the kitchen, the bathroom, and the services that feed them. A 60 square metre dwelling needs the same consent-quality plumbing, drainage, electrical supply and heating decisions as a 200 square metre house, spread across a third of the floor area. That is why a well-built minor dwelling always costs more per square metre than a full house, while costing far less in total.

The costs people forget are outside the building: excavation and the new driveway, trenching power, water and wastewater across the section, connection fees, and development contributions, which in Tasman are assessed through the PIM process even for exempt granny flats, with the minor-dwelling discount applied. Budget these before falling in love with a floor plan. For context on where full-build money goes, our 2026 cost guide breaks down the same categories at house scale.

Yes, and if it is going to be someone’s home, it should be built that way. Small buildings are actually less forgiving than big ones: a 60 square metre dwelling has more outside surface for every square metre of floor, so a poorly built small building loses heat even faster than a poorly built big one. The Building Code’s H1 insulation requirements are the legal floor, not a performance target.

Get the envelope right, high insulation levels, airtight construction, quality joinery and controlled ventilation, the same five principles that drive a Passive House, and the small volume flips from weakness to strength: there is very little air to heat, so a well-built 60 square metre home holds its temperature on next to nothing. For an older parent or a tenant, that means a home that is genuinely healthy in winter, not a sleepout with a heat pump fighting the walls. Small does not have to mean cold, but cheap almost always does.

The pattern we see most in Nelson Tasman right now is near-retirees building a comfortable new home in the back yard, moving into it, and renting the main house to their kids. The family stays together on the same land, the parents get a warm, low-maintenance home scaled to how they actually live, and the property earns twice. A warm, healthy one or two bedroom unit rents readily here because so few exist, and a consented, code-compliant minor dwelling adds real value to the property at sale time, where an unconsented sleepout subtracts it.

A minor dwelling stacks up when three things line up: you already own the land, so the usual biggest cost of housing is already paid; you have a long-term use for it, family first, rental later; and you build it properly, code-compliant, warm, dry and documented. It does not stack up when the whole plan is built on avoiding consent and compressing quality. That saving comes back as leaks, cold, no insurance cover, no bank finance and a headache at sale time. If you cannot afford to do a small building properly, the honest advice is to wait until you can, because a cheap cold box in the back yard is not an asset, it is a liability with a nice photo.

The 70 square metre exemption makes a minor dwelling faster and cheaper to deliver than it has ever been, and for the right household, parents and adult kids sharing one property, a long-term rental, a home scaled to retirement, it is one of the best-value builds available. But the rule change removed the council’s checks, not the physics, so the builder you choose is now the only quality gate on the project.

Build it like it will be inspected, insist on records of work, and specify it warm. If you are weighing up a minor dwelling, a granny flat or a tiny home anywhere in Nelson Tasman, arrange a consultation and we will talk through your section, the pathway that fits, and what it will honestly cost to do well.