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The Ultimate Guide To The Cost Of Building A Duplex In Sydney


Are you considering an investment property? Building a duplex is what you’re looking for. Not only does it offer investment advantages, but it also provides an opportunity to create extra living space. 

The housing market in Sydney and across Australia is experiencing significant growth. However, getting onto the property ladder can be quite expensive. That’s where building a duplex can make more financial sense. It’s a practical choice for those looking to invest in property.

So, if you’re considering building a duplex in Sydney, this guide will provide valuable insights into the cost aspects of the project. Let’s explore the factors that come into play and help you make an informed decision.

What is a duplex?

A duplex is a residential building that consists of two separate dwellings on a single plot of land. These dwellings share a dividing wall but have amenities, parking spaces, gardens, and entrances. This type of property, known as a dual occupancy property, can accommodate two units. Depending on the builder’s approach, a duplex may have one or two titles.

If a duplex has two titles, each unit can be sold independently. On the other hand, if there is a single title, both units are sold together. This flexibility offers various options for residents and property investors.

Many people choose to live in one unit and lease the other, while some may decide to move in with their extended family. As a property investor, you can live in one unit and rent out the other or rent out both units for maximum rental income potential.

Read more: View our duplex design in Sydney, NSW

How much does building a duplex cost in Sydney? 

Building a duplex involves various costs depending on location and specific factors. Here are some average cost estimates for building a duplex in Australia’s capital cities and territories:

1. Land acquisition

The cost of purchasing the block of land can vary significantly depending on the location. In Sydney, for example, land prices can range from $600,000 to $1.5 million, depending on the suburb.

2. Demolition expenses

If an existing structure on the land needs to be demolished, costs can range from $10,000 to $30,000, depending on the size and complexity of the demolition.

3. Construction costs

On average, construction costs for a duplex in Australia can range from $400,000 to $700,000 per unit. Factors such as the size, design complexity, quality of materials, and finishes chosen will affect the overall cost.

4. Labour costs

Labour costs for a duplex builder typically range from 25% to 35% of the total construction cost. This percentage can vary depending on the builder’s expertise and the level of customisation required.

5. Zoning and compliance

Additional costs for zoning and compliance, such as permits, inspections, and modifications to meet building codes. Costs for these aspects can range from a few thousand dollars to tens of thousands.

These are general estimates, and actual costs can vary based on factors such as site conditions, design choices, and fluctuations in the construction market.

Read more: Why a duplex could be your perfect investment? 

How long does it take to build a duplex? 

The timeline for building a duplex in Australia varies based on several factors, including project size and complexity. 

On average, the construction process can take 9 to 18 months. It’s important to note that each project is unique, and site conditions, design intricacies, and permit approvals may influence the duration.

To obtain a more accurate estimate for your specific project, it is recommended to consult with experienced duplex builders. At Provincial Homes, we can assess your design ideas, discuss the scope of work, and provide a tailored timeline based on their expertise and knowledge of local construction practices.

Engaging in detailed discussions with builders and obtaining their professional insights, you can better understand the anticipated timeline for building a duplex.

Read more: Factors for choosing the right home builder in Sydney

What are the different types of duplexes? 

Understanding the different types of duplexes is crucial when considering their construction. The specific type of duplex you choose can significantly influence construction costs and ongoing maintenance expenses. Here are some common types of duplexes to consider:

  • Side-by-side duplex: This type features two units positioned directly next to each other, sharing a common wall.
  • Front and behind duplex: In this configuration, one unit is situated directly behind another, often with a shared backyard or common space.
  • Single-story duplex: Units in a single-story duplex are separated by a vertical wall and are located on the same level.
  • Two-story duplex: This type includes units on different levels, typically with a vertical wall separating them.
  • Horizontal divide: A horizontal divide duplex consists of one upper unit and one lower unit, each with its separate entrance.
  • Triplex: In addition to duplexes, there is also the option of a triplex, which consists of three separate dwellings.

Read more: Our 10-step process from choosing a home to construction completion

How many rooms are in a duplex? 

The number of rooms in a duplex can vary based on several factors, including the property’s size, design, and intended use. While a standard duplex may have two to four bedrooms per unit, larger duplexes can feature more rooms. Here are some standard rooms you might find in a duplex:

For standard duplexes:

  • Bedrooms (typically three to four per unit).
  • Bathrooms.
  • Kitchen.
  • Living room.
  • Dining area.
  • Additional spaces like a study or home office.

For larger duplex configurations:

  • Bedrooms (number can vary per unit).
  • Bathrooms (multiple per unit).
  • Kitchens (one per unit).
  • Living rooms (one per unit).
  • Dining areas (one per unit).
  • Additional rooms such as studies, recreation rooms, or guest rooms (depending on design and size).

The specific room sizes and configurations can be customised based on the owner’s or developer’s needs and preferences as long as they comply with local building regulations. Working closely with designers, architects, and builders will help create the optimal room layout for the specific duplex project.

Read more: Our six-star commitment. Our goal is to build a home that you love and that we are proud of. 

Is duplex the same as semi-detached? 

A duplex and a semi-detached home may look alike, but they differ. In a semi-detached home, two properties are built on separate plots of land, connected by a wall and fence. Each unit is independent and has its ownership.

On the other hand, a duplex is more complex. It consists of two houses on one piece of land, considered one property. They can be sold individually, but they share a familiar title.

So, while they seem similar, a semi-detached home is like two independent houses, whereas a duplex is like two houses on one property.

Read more: Learn more about our 30 year structural guarantee

Do duplexes increase in value? 

Duplexes have shown a tendency to increase in value over time. Recent real estate data indicates that duplex properties in Sydney and other major Australian cities have experienced notable appreciation. This is further supported by specific examples, such as the case of Ms Mills and her duplex developments.

According to Realestate, Ms Mills’ two duplex developments in the suburbs have seen impressive growth in median house prices, increasing about 40% and 60% since she embarked on the projects. These figures highlight the potential for significant value growth in duplex properties.

Past trends may not guarantee future performance. Various factors influence real estate markets, and property value appreciation is not guaranteed. It is advisable to conduct thorough research and assess current market conditions before making investment decisions.

Duplexes are often sought after as dual-income properties, offering potential rental opportunities and the chance for increased rental income. The demand for duplexes with separate entrances, utilities, and enhanced privacy adds to their appeal among buyers and investors.

Data suggests that duplexes have demonstrated value appreciation. It is essential to stay informed about current market conditions and exercise due diligence when considering real estate investments.

Pros of building a duplex

Building a duplex offers several advantages for investors to consider:

  • Potential rental income.
  • Dual occupancy.
  • Property management.
  • Shared expenses.
  • Higher resale value.

Cons of building a duplex

Alongside the benefits, there are some disadvantages to building a duplex:

  • Maintenance responsibilities.
  • Tenant management.
  • Initial costs.
  • Shared walls and noise.
  • Limited design flexibility.
  • Financing considerations.

Is a duplex a good investment? 

A duplex can be a sound investment in Sydney due to its potential for dual-income streams and the opportunity to live in one unit while generating rental income from the other. Investing in a duplex in Australia offers several advantages:

  1. Dual-income potential: With two separate units, you can live in one while generating rental income from the other, ensuring increased cash flow. Additionally, in a city like Sydney, where parking prices average $804.59, you can rent out any extra parking or storage space available, further boosting your income potential.
  1. Tax benefits: Duplex owners may benefit from tax deductions, including:
  1. Property maintenance expenses.
  2. Depreciation of the building and fixtures.
  3. Tax deductions for mortgage interest.
  4. Splitting expenses for maximum deductions.
  1. Strata titling option: If the duplex has a single title, you can consider strata titling, which allows for individual ownership and sale of each unit, enhancing investment potential.
  1. Higher resale value: Duplexes often command higher resale prices due to their unique features, such as dual living capability, separate entrances, utilities, and enhanced privacy.

The success of the investment depends on various factors such as market conditions, location, and individual circumstances, so careful evaluation and professional advice are essential.

It is essential to consult with a tax professional to understand the specific tax benefits available based on your circumstances and ensure compliance with Australian Tax Law.

Read more: View our single and double-storey home locations on display

Financing options for building a duplex

When financing the construction of a duplex, consider the following options:

  1. Construction loans: Specifically for funding the building process, these loans offer flexibility and allow you to draw funds as needed. They typically have higher interest rates and require a thorough project evaluation.
  1. Investment property loans: Tailored for real estate investors, these loans offer favourable terms and interest rates. Lenders assess factors like potential rental income and property value to determine eligibility.
  1. Government grants and incentives: Research local government programs that support housing development. These may provide financial assistance or tax benefits.
  1. Home equity loans or lines of credit: If you have substantial equity in an existing property, consider leveraging it to finance the duplex construction. Assess the associated risks and obligations carefully.

Duplex legal and regulatory requirements

Building a duplex in Sydney requires compliance with various legal and regulatory obligations. Here are the key considerations:

  • Permits and approvals: Obtain necessary permits and approvals from local authorities before starting construction.
  • Building codes and standards: Follow building codes for structural integrity, fire safety, electrical and plumbing systems, accessibility, and energy efficiency.
  • Zoning regulations: Ensure the land is zoned for duplex construction and meets requirements for setbacks, building height, parking, and landscaping.
  • Heritage and conservation: If applicable, adhere to special requirements for heritage-listed or conservation areas.
  • Environmental and sustainability: Consider incorporating eco-friendly features and materials in line with sustainability standards.
  • Engage professionals: Seek guidance from architects, builders, engineers, and town planners with expertise in duplex construction.
  • Local area considerations: Consider neighbourhood guidelines and community expectations for design and aesthetics.

Looking to build a duplex?

With 30 years of experience and a team of qualified professionals, we are Sydney’s premier duplex design builder. Our award-winning designs and tailored solutions ensure your vision becomes a reality. Plus, our 30-Year Structural Guarantee provides peace of mind for your investment.

Unlock the potential of a duplex design for your forever home. Whether you prefer a single or two-storey option, we offer a wide range of flexible and profitable duplex designs at Provincial Homes. Maximise your investment with the opportunity for additional income or create a close living arrangement for a dependent.

Experience the benefits of a duplex home. Double the living space, potential rental income, and flexibility to suit your lifestyle. Contact Provincial Homes today for a free site inspection and explore their beautiful designs. Trust the experts to guide you through your duplex-building journey with confidence.

Frequently asked questions

1. What are the costs involved in building a duplex?

Building a duplex includes land costs, construction materials, labour, contractors’ fees, architects’ fees, council approvals, and additional expenses such as demolition costs or retaining walls.

2. What factors impact the cost of building a duplex?

Factors that can impact the cost of building a duplex include the property’s location, the size and design, the complexity of the construction, the availability of skilled labour, and the current market conditions.

3. How can I determine my borrowing power for building a duplex?

You can use a borrowing power calculator to assess your borrowing capacity based on your income, expenses, credit history, and current interest rates.

4. What are the advantages of building a duplex?

Building a duplex offers several advantages, including the potential for rental income, investment strategies, double the living space, low maintenance costs, and the flexibility to accommodate extended family or generate additional income through rental property.

5. How can architects and contractors contribute to building a duplex?

Architects and contractors play a vital role in designing and constructing a duplex. They ensure the property meets your requirements, complies with regulations, and provide skilled labour for the construction process.