Granny flats have become one of the hottest topics in New Zealand property this year. The recent rule changes allowing some new granny flats to be built without a building consent have made headlines, and for many buyers, they're an attractive feature. They promise flexibility, extra income, space for extended family, or even a work-from-home solution.
But before you get too excited about the rental potential, there's one important question to ask:
Can it actually be legally rented?
Don't Assume Income Equals Value
As real estate agents, we've noticed buyers increasingly factoring a granny flat into what they're prepared to pay for a property. It's easy to see why. The idea of offsetting a mortgage with rental income is appealing.
The problem is that not every sleepout, garage conversion, basement apartment or secondary dwelling can legally be rented as an independent tenancy.
That's why we've started encouraging buyers to investigate these spaces before making assumptions about future income.
A Granny Flat Isn't Always a Granny Flat
The recent REINZ and MBIE guidance highlights something many people don't realise:
A dwelling can be lawful to build but not necessarily lawful to rent.
Some newer standalone granny flats may qualify under the new building consent exemption rules. Others may have been built under traditional building consents.
However, older garage conversions, basement flats and sleepouts often require a much closer look. Just because they've existed for years—or have even been rented previously—doesn't automatically mean they're compliant today.
What Should Buyers Ask?
If you're buying a property with a secondary dwelling, ask your solicitor and request documentation covering:
Was the dwelling lawfully established?
Are there building consents or a Code Compliance Certificate?
Was there ever a change of use?
Is the space shown on council-approved plans?
Does it meet Healthy Homes requirements if rented?
Are any fire separation requirements applicable?
These aren't designed to scare buyers away. They're simply part of good due diligence.
It Can Still Be an Incredible Asset
None of this means buyers should avoid homes with granny flats. In fact, many are fantastic investments.
A compliant secondary dwelling can provide:
Rental income.
Accommodation for parents or adult children.
Space for a home business.
Flexibility as family needs change.
Improved resale appeal.
Properties offering multiple living options continue to attract strong buyer interest across Auckland, particularly as housing affordability remains a challenge.
The Bottom Line
When we help buyers assess a property, we encourage them to look beyond the photos and floorplan.
A secondary dwelling can absolutely add value—but only if you understand exactly what you're buying.
Doing a little extra homework before going unconditional could save significant expense and disappointment later.
If you're considering buying a property with a granny flat, sleepout or converted garage, we're happy to help you understand what questions to ask before making an offer. Sometimes a quick conversation with your agent, solicitor or building professional early in the process can make all the difference.