Why prefab duplexes are on the rise

There are a few good reasons why property developers, investors – and even governments – are talking about duplexes. As multi-unit dwellings, they’re a smart way to extract maximum value and space from your site. Right now, this is especially crucial: New Zealand is in the midst of a housing crisis where every square metre is becoming increasingly sought-after.

In fact, as the graph below shows, the trend towards duplexes is already emerging. Councils today are issuing more consents for multi-unit builds than standalones.

The construction aspect.

But how can you ensure these multi-unit projects are built efficiently and without budget blowouts? That’s where prefabricated construction comes to the fore.

At Advance Build, we provide modern, code-compliant duplexes. And, thanks to our offsite construction, all within a guaranteed timeline.

Here, we’re going to explore the rising popularity of duplexes. We’ll look at the pros and cons to consider, what to expect from the development process and why prefab construction is the simple, hassle-free approach.

What’s driving the duplex boom?

There are a few different levers at play. But largely, it comes down to a housing market with insufficient supply and unaffordable prices. In turn, this has prompted buyers to invest in more affordable multi-dwelling properties. The Government has also responded to market conditions by relaxing the rules around duplex consents.

Here’s what the data says:

As at April 2025, New Zealand’s median house price was $781,000 – up from $455,000 in 2015. That’s an average 5.55% annual increase over the past decade. This rapid growth has fuelled demand for more affordable, efficient housing options like duplexes.
The Government’s Medium Density Residential Standards (MDRS) allow for up to three dwellings (up to three storeys) on one site without resource consent. This has simplified duplex development and opened new opportunities for investors and developers.
Higher rental yields make multi-unit homes especially attractive to investors compared to traditional standalone houses.

Weighing it all up

If you’re an investor or developer, you might be wondering whether a duplex is the right strategy. Let’s break down the pros and cons.

The pros of duplexes

We’ve covered some of these already. But essentially, the real benefits of investing in a duplex are:

Higher rental income per site – Instead of one tenant paying you rent, you could have several. This can significantly increase your property’s yield.
Flexibility – If you build multiple dwellings on one site, you can choose to live in one and rent out the rest. This gives you a reliable source of income – and allows you to keep a close eye on your property.
Less risk of vacancies – You may have periods where one of your houses is empty, but it’s unlikely you’ll be without tenants in all of them. This buffers you somewhat from lost rental income.
Shared fixed building costs – If you’re constructing multiple dwellings on one site, your costs (e.g. consents) are shared across each home. This can reduce overall construction costs.

The cons of duplexes (and how Advance Build manages them)

While there are plenty of pros to building duplexes, there are, of course, some drawbacks. The good news? Advance Build can help you navigate them.

Consent complexity – Any building project can throw up consent challenges, but it can get especially complicated with multi-dwelling builds. The Advance Build team can manage this process for you. We support you throughout your entire construction journey – including planning, design and consents.
Higher upfront investment – Multi-dwelling projects, such as duplexes, will generally call for a larger upfront investment than a single dwelling. But remember: your potential long-term gains will also be higher.
Longer build times – The more homes you construct, the longer your build will take. However, because Advance Build constructs its prefab duplexes in our offsite factory, we avoid the weather delays inherent to traditional construction. This guaranteed timeline gives you peace of mind – and also means you can recoup your investment faster.
More material waste + site impact – Again, if you’re building more than one home, you’ll create more waste – and leave a heavier environmental footprint. The beauty of Advance Build’s prefabricated duplex construction is the precision-controlled approach we can take in our factory. This means less waste – and less site disruption, too.

Why prefabricated duplexes are a smart option

If you’re thinking about developing or investing in a duplex, it’s worth recapping the reasons why the prefab path works.

Building a prefabricated duplex home means:

Time-certainty – Taking construction offsite and into our controlled factory environment means you get a guaranteed completion date. No weather delays or onsite complications!
Cost-certainty – Without weather-related building delays, you can avoid budget blowouts and unexpected costs.
Less onsite disruption – Offsite factory construction means less time spent onsite – and, in turn, less noise, mess and traffic.
Consistent quality – Advance Build’s strict quality control and inspection processes means every project is built to the same high standard – and your home is built to last.

The Advance Build development process

So what exactly does a prefab duplex project look like? Since opening our doors 16+ years ago, we’ve honed our process to make it as straightforward, simple and stress-free as possible.

The 6-step journey looks like:

Project discovery – This is when you tell us about your project: your vision, budget, design and timeframe. We’ll design a scheme plan, give you a budget estimate and assess your site.
Getting started – We complete the project analysis so we can provide you with accurate and detailed costings. This includes third party reports and initial council approvals. This is also when you put your deposit down (deductible from the total price).
The contract – We’ll finalise all the details, you’ll sign the contract – and we’ll move ahead with your final project design. We’ll also submit drawings to council, after which the pre-construction team will finalise design documentation and construction.
Factory build – Your build is underway! It takes 8 weeks to complete in our controlled factory environment.
Onsite construction – Your prefabricated duplex is delivered to site and expertly installed. Your dwelling is connected to its foundations and all services.
Handover – Your build is complete! You’ll receive the Code Compliance Certificate and all warranty information.

Ready to build a prefab duplex?

If you’re in the market to develop or invest in a duplex, think about the prefabricated path. You’ll get a high-quality home that’s quick to build, cost-certain and stress-free. And Advance Build takes care of everything – including design, planning, construction and consents.

Book a free site assessment today or chat through your plans with our team.

Not quite ready? Check out our FAQ section below.

FAQs

Can I build a duplex on any residential property in Auckland, Northland or Waikato?

Not necessarily. It depends on your property’s zoning, site size and council’s planning rules.

In Auckland, the Medium Density Residential Standards (MDRS) generally allows up to three dwellings per site (in qualifying urban zones) without needing resource consents. But, it’s worth checking the Auckland MDRS guide first – you may be limited by overlays or ‘qualifying matters’.

In Northland and Waikato, each local and regional council has its own rules – and these can vary significantly. Before you start, check your property’s title for any consent notices or covenants. These can put additional restrictions on any development.

And remember: Advance Build offers a free site assessment to help determine what’s feasible for your property.

How long does it take to build a prefab duplex with Advance Build?

Just 8 weeks!

Like all our builds, our duplexes are constructed using a streamlined process inside our controlled factory environment. Because we take construction offsite, we avoid the usual delays caused by weather or site access. This gives you a more predictable, efficient experience – without budget blowouts.

Are construction loans available for prefab duplexes in New Zealand?

Yes.

Most major banks, such as ASB, ANZ and Kiwibank, offer construction loans for prefab builds. However, the lending conditions may differ slightly from traditional build loans. Usually, they require staged drawdowns aligned with project milestones.

Do I need to manage council consents myself?

No.

Advance Build manages the entire consent process for you. This includes working with your local and regional council to ensure you comply with all rules and regulations.

This approach is part of our full-service design-and-build model, which includes all building and resource (if required) consents, as well as service connections.

What do I need to consider as far as ongoing maintenance and durability?

Prefabricated homes are built to the same New Zealand Building Code as traditional ones. They must meet all structural, insulation and fire-rating standards set out by the Code.

At Advance Build, we adhere to strict quality control processes so we can construct all our homes to the same high standard each and every time.

How are noise and fire safety handled in a prefabricated duplex build?

The same as any home constructed by Advance Build! All our homes (including duplexes) meet the New Zealand Building Code standards for noise reduction and fire safety. Each unit includes fire-rated separation walls and acoustic insulation to minimise sound transfer between dwellings.

Privacy and peace of mind guaranteed!