Granny flat, minor dwelling or secondary dwelling – what’s the difference?

If you’ve started looking at adding another home to your property, you’ve probably already come across a few different names.

Granny flat. Minor dwelling. Secondary dwelling. Small standalone dwelling.

So, what’s the difference?

For most people, not a lot. They’re different terms used to describe much the same idea – a smaller, self-contained home on a property where there is already a main house.

But there are a few things worth knowing, particularly when you start talking to builders, looking at prices or working out what you can actually build on your property.

What is a granny flat?

“Granny flat” is probably the term most of us are familiar with.

Traditionally, it meant a small home built for Mum, Dad or another family member. These days, the people we talk to are considering them for all sorts of reasons.

It might be a home for a parent who wants to be closer to family without giving up their independence. It might be somewhere for an adult child to get started. Or you might be thinking ahead and creating a smaller home for yourself while another generation moves into the main house.

Whatever the reason, the important bit is the same: it’s a home.

It should be warm, comfortable, practical and built to last.

What is a minor dwelling?

“Minor dwelling” is another term you’ll hear regularly, particularly when talking about planning, property and building.

Generally speaking, it describes a smaller residential unit on the same property as a main dwelling.

You may also see the more specific term detached minor residential unit. That is the terminology used in New Zealand's current national planning standards for qualifying detached dwellings commonly known as granny flats.

So if you search online for “minor dwellings Canterbury” rather than “granny flats Canterbury”, you’re often looking for essentially the same type of housing solution.

And what is a secondary dwelling?

“Secondary dwelling” is another commonly used description.

Again, the clue is in the name – it’s an additional dwelling on a property that already has a primary home.

Different councils, professionals, websites and homeowners can use slightly different terminology, which is why you'll see all three terms when you're doing your research.

We tend to use granny flat and minor dwelling most often because they're terms our customers recognise. But whether you call it a granny flat, minor dwelling or secondary dwelling, what matters to us is creating a proper home that works for the people who will live in it.

What about the new granny flat rules?

This is where terminology – and good advice – becomes a little more important.

Since 15 January 2026, certain new, standalone, single-storey granny flats of up to 70m² can be built without a building consent, provided they meet all of the conditions of the exemption. They still need to comply with the New Zealand Building Code, the work must be carried out or supervised by licensed building professionals, and there is still a council process to follow, including obtaining a Project Information Memorandum (PIM).

In other words, “no building consent required” does not mean “no rules apply”.

There are still requirements around your site, design, construction, planning and documentation. And not every small dwelling will qualify for the exemption. If the exemption conditions aren't met, the normal building consent pathway applies.

That's why one of the first things we do is help you understand what's actually possible on your property.

A cheap granny flat isn't always a cheap finished home

This is something I feel quite strongly about.

If you've been searching online, you'll probably have seen some very attractive prices for small homes and transportable granny flats.

There is absolutely a place for different types of construction and different budgets. But please make sure you're comparing apples with apples.

An advertised price for a transportable building may not represent everything required to turn that building into a completed, compliant home on your property.

Before you compare prices, ask exactly what is included.

Does the price include the foundations required for your site? Transport and installation? Service connections? Electrical and plumbing work? Site preparation? Council requirements? Heating? Flooring? Appliances? Window furnishings? Decks or access? Professional fees? Completion documentation?

And, importantly, who is responsible for making sure everything comes together properly?

A price can look fantastic at the beginning and become quite different once all the things required to create a finished home are added.

We would much rather help someone understand those costs upfront than have them discover them halfway through a project.

Quality matters – especially with a smaller home

Small doesn't mean temporary and it certainly shouldn't mean second-rate.

Someone you care about may be living in this home for the next 10, 20 or 30 years. Or it may eventually become your own home.

Good insulation, quality materials, proper foundations, thoughtful design, reliable trades and good workmanship matter just as much in a 60 or 70m² home as they do in a much larger one.

There are also practical things that become even more important in a smaller space – storage, natural light, room proportions, accessibility, heating and how easily you can move around the home.

We've been in construction for a long time, and one thing we've learned is that the cheapest solution isn't necessarily the one that costs you the least in the long run.

Know what you're actually buying

My advice is pretty simple: ask lots of questions.

If you're comparing granny flat builders or minor dwelling options in Canterbury, don't be afraid to ask exactly what's included and what's not.

Ask who is building it. Ask about warranties and guarantees. Ask what happens if something goes wrong. Ask what you'll need to organise yourself. Ask what additional costs could come up because of your particular property.

And if somebody can't explain it to you in plain English, keep asking until they can.

You shouldn't need to understand the Building Act or become an expert in construction just to make a good decision. That's our job.

So, what should you call it?

Call it whatever makes sense to you.

A granny flat, a minor dwelling, a secondary dwelling or simply Mum's new house across the lawn.

For us, the name isn't the important part.

It's about understanding why you're building it, making sure it's right for your property and your budget, and creating a quality home that someone will genuinely enjoy living in.

And if you're only at the beginning and have no idea what's possible yet, that's absolutely fine.

Have a chat with us. We'll help you work through it – without the jargon, without the pressure and without trying to sell you something that isn't right for you.