Duplex Architects Sydney

The Evolution of Duplexes in Sydney

Duplexes, as we know them today, have a relatively recent history in Sydney. While multi-unit dwellings existed in various forms throughout the city's past, the modern duplex only emerged as a popular housing option in the mid-20th century.

Many of the original duplexes were more practical with rudimentary designs reflecting the functions of their era. Modern duplex designs and materials can create beautiful homes that look and function almost the same as any new high-end home.

Currently, there are three standard types of duplex configurations: side-by-side, front-rear (attached) and upstairs-downstairs. The third type is designated as a Class 2 building under the NSW Design and Building Practitioners Act 2021, requiring a Class 2 registered architect. All types can be single or 2-storey duplex designs subject to specific Council height/ shadowing/ setback guidelines etc.

Several factors contributed to the rise of duplexes in Sydney:

• Population Growth: The city's expanding population created a demand for more housing options. Duplexes, with their potential for higher-density living on a single lot, offered a solution to meet this need.

• Land Availability and Affordability: As land prices in Sydney increased, building duplexes became a more efficient way to utilise available space, split the land cost between two dwellings and, for developers, to maximise returns on property investments. Building duplexes can be a highly profitable way to optimise a single lot and increase property value.

• Rental Income: Duplexes offer the potential for rental income, providing a source of passive income or helping to offset mortgage payments.

• Lifestyle Benefits: Duplexes can offer a more affordable housing option compared to detached houses, while still providing privacy and a sense of community.

• Changing Lifestyles: The shift towards smaller household sizes and the growing acceptance of multi-unit living make duplexes an attractive choice for many.

• Feels More like a House than a Unit. Unit living normally entails communal parking and multi-storey buildings, whereas a duplex feels more like a home, often allows on-site parking, and, usually, is less-expensive than a detached house.

• Cost-Effective New Home: You can knock down your old home, build a smaller new home, and use the profits from the other duplex sale to reduce your overall costs. At the very least someone is buying half your land so that money comes back to you for the development. 

• Councils Have Become More Supportive: As large house blocks have become less fashionable, and Councils are pushed by State Government to increase densities, duplexes are an increasingly desirable option. Standard house blocks with older homes in popular areas can be re-developed as a duplex, increasing the rates a Council receives while needing no extra real infrastructure (roads, electricity, public transport, etc). This change has opened the door for well-designed duplexes to be built on suitable sites and create great outcomes.

• Having Family Close By: Well-designed duplexes allow family members to live next door to each other for convenience and safety, while preserving household space and privacy. Some families have no rear fencing, combining their backyards for further connection. 

• Clever Design: Architects who embrace the benefits of duplex design can create some amazingly functional and beautiful spaces. Clever use of available light (courtyards, positioning), awareness of neighbour privacy (directional shades, window heights), modern materials, insulation and engineering, along with mid- to high-level materials, produce a luxury look and feel. 

Recent Regulatory Changes

The landscape of low-rise and duplex developments in NSW is evolving, with recent regulation changes aimed at promoting diverse and well-located homes. These updates are essential for developers and homeowners looking to navigate the duplex and dual occupancy market successfully.   

Key Changes

• Streamlined Approvals: The NSW Government has simplified the approval process for dual occupancies and semi-detached dwellings, particularly in Zone R2.

• Emphasis on Diversity: The government's policy seeks to diversify housing options in areas with good access to amenities and services.

• First Stage Implementation: The first stage of these changes has already been implemented, focusing on low and mid-rise housing.

• Upstairs-Downstairs: This duplex configuration type is designated as a Class 2 building and subject to Class 2 regulations under the NSW Designers and Building Practitioners Act 2021.

What This Means for Duplex Owners and Developers

These changes present a significant opportunity for those involved in the duplex market. The streamlined processes and emphasis on well-located, diverse housing make it an ideal time to consider duplex developments.

Key Considerations

• Stay Informed: Keep up to date with the latest changes in planning laws.

• Consult with Experts: Work with experienced Architects and planners.

Focus on Location: Take advantage of the emphasis on well-located homes.

• Land size and zoning: The rules change from Council to Council; however, generally, you will need R1 or R2 zoned land and some Councils have extra flexibility or requirements. You will need to have enough land to meet regulations, and, of course, the space to build two homes with sufficient soft landscaping to fulfill Council requirements. 2-storey duplex designs can be used effectively where the land space is limited, whilst single storey might be preferred on larger sites to help with Accessibility concerns, reduce stairs and they’re often cheaper to build.

• Local Regulations: Duplex designs must comply with local zoning laws and building codes, including boundary setbacks, privacy concerns, shadowing of neighbours, 7-star NatHERS or PassiveHaus compliance and BASIX, amongst others.

• Architectural Style: The chosen architectural style should complement the surrounding neighbourhood and reflect the owner's personal preferences, including budget.

• Layout and Functionality: The internal layout should be designed to maximise living space and provide comfortable and functional living areas. Driveway positioning is important, as is an awareness of natural light sources.

• Common wall practicality. All duplexes will have at least one common wall, even front and back duplexes separated by a garage. Consideration needs to be given to noise reduction as well as fire separation. 

• Outdoor Space: Adequate outdoor space, such as courtyards or balconies, is essential for enjoying the benefits of duplex living.

The suitability of a location for building a duplex depends on various factors, including:

• Zoning Restrictions: Some areas may have restrictions on duplex development while other Councils encourage it. Even if zoning allows, higher-density suburbs with smaller blocks, like Surry Hills, might be unsuitable for duplexes, or there are better build options. Whereas, on the Northern Beaches, as an example, the area’s typically larger lots and views / outlooks can easily accommodate a duplex and sharing the views makes sense. 

• Proximity to Amenities: Consider the proximity to schools, shops, transportation, and other amenities, as some Councils allow increased density within 800 metres of a train station. 

• Land Prices: Land prices can vary significantly across different suburbs in Sydney.  You need to be aware of the build costs plus additional consultants, Council fees, etc to avoid over-capitalising, if this is a concern to you.

• Liveability outcome. Whilst some developers might build a duplex just for financial return; ideally, the amenity of all the occupants should be considered. A well-designed duplex will ensure that both houses enjoy light-filled open spaces, privacy and comfort.

The process of building a duplex typically involves the following steps:

1. Land Acquisition: Confirm the zoning and minimum land sizes with a Town Planner and/or Architect, then purchase a suitable piece of land.

2. Design and Planning: Create a brief and work with an Architect to develop the duplex design. The architect will produce the required drawings to submit to Council and obtain the necessary approvals.

3. Construction: Hire a builder to construct the duplex. Any good builder can build a duplex; you just have to make sure their insurance covers the scope of your build.  Ideally, they will have duplex experience around planning efficiencies for building two houses at once and understand fire standards, as there is a fire separation wall required for duplexes. At Archisoul we have many good builders on our books, tried and proven, and we can assist with finding the right ones for you. If needed, we can manage the whole process to the handover of keys.

4. Completion and Settlement: Once construction is complete, the duplex is ready for you to obtain your Occupancy Certificate and move in, or proceed to sale. If selling one or both is your plan, you can start the marketing well before the house is complete.

The cost of building a duplex can vary widely. It is essential to obtain accurate cost estimates from builders and architects to get a realistic idea of the total project cost. As a rough rule-of-thumb for a quality build you could assume $5,500 m² (incl. GST) for the building, say $2,200 m² (incl. GST) for the driveway and basic landscaping, and add 20% on top for Council fees, Architectural drawings/ project management, consultant fees, etc. $4,400 m² might be achievable for the build cost assuming modest materials, appliances, design, and an easy block.

Some Sydney suburbs might also be a little cheaper due to reduced labour cost or competition, and of course some higher. Difficult site access, steep blocks, cantilevers, fire zone materials, flood mitigation, etc can all increase the costs. In some cases, modular home construction can reduce costs and build time.

Additional Considerations

• Dual Occupancy: If you plan to occupy one unit of the duplex yourself, consider the potential impact on your lifestyle and privacy.

• Strata Title: Duplexes are typically sold as strata title properties, which means that the owners share responsibility for common areas and maintenance costs.

While the term "duplex" implies two attached dwellings, configurations can vary widely. The common duplex design types are:

• Side-by-Side: This is the most traditional layout, where the two units are built side-by-side, sharing a common wall. Typically, car parking or a garage is at the front.

• Front-Rear attached: In this arrangement, one unit is situated behind the other, often with a shared driveway or courtyard.

• Top-Bottom (Upstairs-Downstairs): This involves a stacked design where one unit is built above the other. Parking can be in front or with a driveway to the side leading to rear parking. Some Councils don’t like Top-Bottom, and this format also falls under the Class 2 requirements, meaning Class 2 registered Architects/ Certifiers/ Engineers/ Builders, etc must be used throughout the process. Fortunately, Archisoul Architects are duplex designers and also Class 2 registered.

• Attached via a Common Structure: The duplexes may be connected by a common wall, attached garage or breezeway. If not, they are typically viewed as secondary dwellings rather than duplexes. This distinction is important, as it can impact zoning regulations and other legal requirements.

Beyond the financial advantages of maximising land value and potential rental income, duplex living offers several lifestyle benefits:

• Community and Connection: Duplexes often foster a sense of community, as neighbours may share common spaces or interests.

• Affordability: Compared to detached houses, duplexes can be a more affordable option, especially in high-demand areas.

• Privacy: While sharing a wall with a neighbour, duplex occupants still enjoy a reasonable degree of privacy.

• Flexibility: Duplexes can be designed to suit various lifestyles, from single individuals to families.

• Local Zoning Regulations: Ensure your duplex design complies with local zoning laws, which may limit the number of units allowed on a lot or specify minimum lot sizes.

• Design Aesthetics: Choose a design that complements the surrounding neighbourhood and reflects your personal style.

• Energy Efficiency: Incorporate energy-efficient features to reduce utility costs and environmental impact.

• Accessibility: Consider accessibility features to accommodate individuals with disabilities.

• Maintenance and Strata Fees: As a duplex owner, you may be responsible for maintaining common areas or paying strata fees.

At Archisoul Architects, we specialise in creating innovative and functional duplex designs that meet your specific needs. Our team of experienced architects can assist you with:

• Design Consultation: We will work closely with you to understand your vision and goals for your duplex project, assess the Council requirements and ensure that your budget is suitable for the scale and outcome you desire. We can also assess whether it is a Class 2 building. Side-by-side configurations, currently, are not, but there are moves afoot to designate all duplexes and semi-attached homes as Class 2 buildings.

• Professional Advice: Your project will require many decisions along the way, from the initial duplex format, parking, land restrictions, energy-efficiency goals, materials, custom build or modular, which engineers/consultants are better/ more responsive, whether to tender out the build or not, etc. We have 28 years’ experience and will be by your side throughout the process, sharing our lessons and contacts.

• Concept Development: Our architects will create initial design concepts that incorporate your preferences and requirements in balance with the Council and site constraints. You get to choose the preferred design options.

• Permits and Approvals: We'll handle the necessary permits and approvals to ensure a smooth construction process.

• Building Supervision: We can also oversee the construction process to ensure it adheres to your design and budget, as required.

Duplexes offer a versatile and rewarding housing option in Sydney. By carefully considering the various factors involved and working with experienced professionals like Archisoul Architects, you can create a duplex that meets your needs and provides a valuable investment for years to come. 

Our team of skilled architects can assist you with every aspect of your project, from initial design concepts to builder tendering and build supervision. We are committed to providing high-quality designs that exceed your expectations while meeting your specific needs and budget.

Make contact today and let’s start the conversation.