Sydney Duplex Regulations: A Guide for Potential Duplex Builders

How nice would it be to invest in a family home that has the potential to make you money? A duplex build could provide you with that flexibility. It’ll ensure you have ample space and privacy, but also earning power, all within the bounds of your investment property.

If you’re looking to house a family member in easy reach, or want to rent out a property within arm’s reach of yourself, a duplex is the perfect solution.

The flexibility duplexes offer and the chance to earn extra money are just two of the reasons duplex builds are growing in popularity in Sydney, and why the building of custom homes has become so attractive to investors. There are also many adaptations you can make to a duplex once it has been built.

But once you’ve invested in building a duplex, you want to ensure you adhere to planning laws and regulations. No one wants to have their plans derailed by technicalities.

Let’s dive into what you need to think about.

What is a Duplex?

A dual occupancy, or duplex home, consists of two separate properties built together on one lot. Essentially, it closely resembles a classic semi-detached property, but the two houses are built parallel to one another.

The houses share elements such as walls and roofing, but are both independent of one another. If you build an entire duplex, this provides you with space to house both your own family and someone else. A little extra rental income is always welcome!

There are of course many different types of dual living, and a duplex is not to be mistaken for a granny flat. Granny flats are deemed a secondary dwelling, and cannot be dissociated and sold on from the primary dwelling house. The second unit in a duplex is another primary dwelling, and if you’re in a pinch, it could be sold independently of the other property.

Key Duplex Rules and Regulations in Sydney

Let’s consider the various regulations that exist in Sydney.

Zoning Requirements

In NSW, every property falls into a “zone” and will have a residential zone code ascribed to it. As such, each property has to adhere to the rules of that zone set by the local council.

The zoning regulations determine the density of people living there and the intention of the land. It is important to open the lines of communication with your local council as soon as you’ve committed to your build.

Duplex builds are largely permitted in residential zones R1, R2, and R3, and in zone RU5 (rural villages). It is important to check which zone your intended plot falls within before you begin the planning process.

Minimum Lot Size

The minimum lot size for dual occupancy buildings in New South Wales is 400 square metres (or the minimum size required by the local council) and 12 metres wide. Per property, this boils down to 200 square meters and 5.5 metres width per property. But depending on your plans, your build might need more space than this.

In order to calculate the minimum required area of land you need, you need to consider the front, rear, and side setbacks, the size of the property itself, and the space required for at least one off-street parking space.

An exemption from these minimum size requirements can potentially be found in clause 4.6 of the council LEP (local environmental plan) if it is deemed that “there are sufficient environmental planning grounds to justify contravening the development standard”.

Setback and Building Height Restrictions

Building height restrictions include:

●      The maximum height your new duplex can reach is 8.5–9 metres tall.

●      The Floor Space Ratio (compared to the total plot size) in NSW depends on the zoning regulations, though new regulations suggest it is likely to be around 0.65:1.

You need to ensure you have the right setbacks around the property. This can vary depending on the road, but as a general guideline, you can expect the following to apply:

●      Minimum side setback: 0.9 metres (larger setbacks are required for blocks wider than 24 metres).

●      Minimum street front setback: 6 metres.

●      Minimum rear setback: 8 metres.

●      Minimum setback for a pool/spa from side or rear: 1 metre.

Parking Requirements

You need to ensure there is at least one off-street parking space for at least one car per unit, and that the lot has access to a public road. This is to prevent congestion on the road, easing local traffic.

What are Some Additional Things to Consider?

Beyond the measurement and mathematics, there are a few other considerations to bear in mind. The following legal considerations are important for your duplex build:

Local Council Regulations

Your local council has the power to grant or deny you planning approval. It is important to consult with them and to keep them updated throughout the building process. All councils are bound by the NSW government’s Low Rise Housing Diversity Code.

To streamline duplex building in NSW, some duplex properties can be approved by private building certifiers, who can obtain a Complying Development Certificate (CDC). The most important factors at play to allow you to obtain a CDC are adhering to local council environmental regulations. 

You will also need to apply for an Owner-Builder permit, since you’re not one of the many property developers who build these types of homes.

Strata Title Laws

There are two types of title ownership for a duplex:

●      A Torrens title, whereby you own the freehold to both dwellings and the land.

●      A Strata title, by which you own only your own unit and share responsibility for common areas with the owner on the other side.

If you opt for the latter, it could initially save you money, but it may affect the overall value of your own individual unit on the property market.

You would need to set up an owners corporation with your neighbour for management of the common areas. If you and your neighbour don’t see eye-to-eye on something, you would have to look into methods of dispute resolution.

Strata title laws require you to obtain a specialist type of insurance for the common areas. If you obtain a Torrens title, you’re solely responsible for the buildings insurance.

Tax Implications

Are you intending to rent out the second property on your duplex development? Remember, you always need to pay tax on rental incomes you receive. However, you can deduct any expenses, including mortgage interest and maintenance.

In the long term, tax depreciation is another avenue to explore with your duplex house – it requires an initial valuation once the build is completed.

The benefit of opting for a duplex is that it stands on one title, meaning you pay one lot of stamp duty and council tax rates.

Environmental Impact and Sustainability

Duplexes, by the nature of their design, tend to conserve energy. But this can be offset by the fact that the build of a duplex requires almost twice the materials of a regular house.

It is important to adhere to NSW’s local environmental plans and regulations. You will require a BASIX certificate, and will want to follow sustainability guidelines on features to install in your house, such as insulation and optimized window glazing.

Some R2 (low density residential zone) areas have, as of 1 July 2024, excluded dual occupation dwellings owing to factors such as bushfires and floods.

Legal and Insurance Considerations

Even if building a single occupancy building, you should elicit the services of a solicitor. It is doubly important to do this with a duplex, given the potential dual purpose the property will hold for you.

Your insurance needs are contingent on whether you’re in a strata scheme or hold a Torrens title for your duplex. If you hold a Torrens title, you can expect to insure the whole plot, and you will be liable for all maintenance on the property.

How to Choose the Right Builder for Your Duplex

It is important to build a good relationship with your builder – after all, you’re trusting them with your life’s savings.

The key to ensuring this relationship is mutually beneficial is in selection of the right builder. Browse online and compare quotes from a variety of builders, and read reviews on websites such as TrustPilot or NSW Fair Trading.

Things to look for in your builder include:

●      A NSW builder’s licence – this ensures they have experience and the necessary credentials.

●      A realistic understanding of the timings for the scope of your work.

●      A background in building similar projects.

Common Challenges With Duplexes

Let’s run through some common challenges of duplex construction. Here’s what to consider:

●      Complexity: Building two homes on one plot is complex. Construction will require twice the materials but on much less land than a single occupancy property. It can appear cramped, and construction costs can look scary, but you just need to remind yourself you’re investing in two properties here.

●      Tenant difficulties: Being next door to your tenant can be a blessing and a curse. You’re always on hand to help, but then again, you are always on hand to help. You will want to ensure you have strong contracts drawn up before your tenant moves in. And perhaps soundproof any common walls.

●      Maintenance disputes: If you opt for strata titling and you have shared amenities, such as in the garden, and fencing, you will need to bear in mind who will shoulder the costs of maintenance, and how this will be decided.

Summing up

If you’ve decided to maximise your earning potential with your property, and want to build duplex houses in Sydney, you have some simple considerations to take into account. Selecting the right builder, consulting with the council, and ensuring you stick to the planning rules and regulations, are three ways to make your duplex ownership journey run smoothly.

Looking to explore duplex living options? Provincial Homes can help. Browse our range of duplex designs here and arrange to view our display homes. View our customer testimonials here, or continue your journey with us by calling us on 02 9629 5200 or making an enquiry with our offices.

Frequently Asked Questions

How do I know if my proposed duplex meets the zoning regulations?

You can research NSW zoning regulations, and discover which zone your intended duplex site will be in and speak with your building designer, and your builder, to ensure your design and build meet the regulations of your zone.

Do I need council approval to build a duplex?

The approval of some properties in NSW can be fast-tracked by the private Complying Development pathway. If you find your property isn’t eligible for this, you would need to obtain development approval from the council.

What are the common issues that may arise during the duplex approval process?

Duplex approval pathways can be more complex and therefore take longer than a single occupancy home. Fortunately, NSW’s housing reforms considered this, and have put in measures to keep up the much-needed housing supply.

To fast-track the process, development applications for duplexes can be approved by a private Complying Development Certificate (CDC). However, getting this approval comes with its own unique set of rules; the most important factors here are environmental. 

What is a body corporate, and how does it apply to duplexes?

A body corporate is set up to manage and maintain the common areas in a multiple occupancy dwelling, such as an apartment building. If you are acting as a sole landlord to one other property, this isn’t necessary for your duplex. If you opt for a strata title, you would instead need to set up a two-person owners corporation.

How do I find the right duplex design for my property?

For the right duplex design, consider what your intention is for the second property, and how much privacy your family will require. Explore our range of duplex property designs here or check out our designs in person at one of our display homes.