Building a duplex is an exciting opportunity, whether you’re seeking extra income, space for family or a smart investment. However, duplex projects come with their own unique challenges. Avoiding common mistakes can save you time, money, and stress. Here’s what you need to know to ensure your duplex build is a success.
Key Duplex Mistakes & Solutions
| Mistake | Solution |
| Ignoring council regulations | Consult local experts, check requirements |
| Poor site selection | Conduct thorough feasibility studies |
| Inadequate privacy/noise | Use soundproofing, smart wall placement |
| Choosing wrong builder | Hire experienced duplex builders |
| Legal/title confusion | Clarify title type and management upfront |
Local Regulations and Approvals
One of the biggest pitfalls is underestimating the complexity of local council regulations, especially with recent changes in New South Wales (NSW). The NSW government introduced new duplex laws in 2024 and updated them in 2025 to encourage more dual-occupancy developments, making it easier for homeowners and developers to build duplexes across many council areas. Key changes include a minimum lot width of 12 metres and a minimum lot size of 450 square metres, along with a mandatory allowance for duplexes in R2 residential zones in many councils.
Ignoring these regulations or failing to stay updated can cause costly delays or even project rejection. It’s essential to consult local council guidelines and engage professionals who understand these evolving laws. Builders like Kurmond Homes, a trusted Sydney-based duplex specialist, have in-depth expertise in navigating these regulations, ensuring your project complies and progresses smoothly.
Kurmond Homes has recently updated all duplex designs to fully comply with the NSW Low-Rise Housing Diversity Code. This means our homes are not only modern and functional, but also meet the latest planning and zoning requirements, saving you time, hassle, and potential redesign costs.
Whether you’re working with a narrow lot or a tricky block, you’ll find compliant designs that maximise space, privacy, and value.
Site Selection and Design Pitfalls
Choosing the right block and designing your duplex to suit it is critical. Many first-time builders overlook site constraints such as slope, irregular shape or poor access, which can dramatically increase costs and complexity.
- Conduct a thorough site assessment: Before purchasing land or committing to a build, have professionals evaluate the block’s suitability for a duplex.
- Orientation matters: Poorly oriented duplexes can suffer from inadequate sunlight and higher energy bills. Position living areas to maximise natural light and cross-ventilation.
- Plan shared walls carefully: For bedrooms or bathrooms, sharing a wall with the neighbouring unit can create noise and privacy issues. Use staircases or non-living spaces as common walls where possible.
Kurmond Homes offers custom duplex designs tailored to your site and lifestyle, ensuring optimal use of space and privacy without sacrificing comfort or style.
Budgeting and Financial Oversights
Duplexes often come with hidden costs that catch inexperienced builders off guard. From extra site works to separate services for each dwelling, expenses can quickly add up.
- Budget for contingencies: Always allow for unexpected costs. Get detailed estimates from professionals who understand duplex builds.
- Avoid overcapitalising: While adding luxury features is tempting, not all upgrades will increase your property’s value or rental appeal. Research what buyers and renters in your area actually want.
- Don’t skip feasibility studies: Investigate local property values, rental yields, and resale potential before you start. A comprehensive feasibility study can prevent costly mistakes down the track.
Choosing the Right Builder and Materials
Not all builders have experience with duplexes. Selecting the wrong builder can result in design flaws, compliance issues and project delays.
- Choose experienced duplex builders: Look for a builder with a proven track record in dual-occupancy projects and strong knowledge of local regulations.
- Prioritise quality materials: Duplexes see more wear and tear due to higher occupancy. Invest in durable, low-maintenance finishes to reduce long-term costs and boost property value.
Kurmond Homes is a multi-award-winning family-run builder renowned for delivering high-quality duplex homes with premium inclusions as standard, backed by a six-year structural guarantee.
Utilities and Services Mistakes
Planning for utilities is more complicated in a duplex than in a single home. Overlooking this can lead to disputes and headaches later on.
- Separate services: Each unit should have its own water, gas, electricity, and internet connections. This makes future sales, rentals, and maintenance much simpler.
- Plumbing and drainage: Poorly planned plumbing especially with back-to-back bathrooms can cause noise and ongoing maintenance issues. Work with your builder and plumber to ensure efficient, quiet, and accessible services.
Kurmond Homes’ experienced teams ensure utilities are properly separated and designed for convenience and compliance, avoiding common pitfalls.
Planning for Privacy and Noise Control
Privacy and noise are common concerns in duplex living. Overlooking these factors can lead to ongoing dissatisfaction for occupants.
- Invest in soundproofing: Use acoustic insulation between units, especially in shared walls, floors, and ceilings.
- Create private outdoor spaces: Each unit should have its own outdoor area to enhance appeal and rental potential.
How To Find A Builder For Your Duplex Home
Kurmond Homes has years of experience building duplex homes and can provide initial advice on whether your land is suitable.
On the Kurmond website, you’ll find multiple Duplex designs with many façade and layout options and if these don’t suit you and your family, we’ll help you design your ideal duplex home.
To discover more about building your dream duplex, contact Kurmond Homes today or visit one of our display homes.
Conclusion
Building a duplex is a significant investment financially and emotionally. The key to success lies in thorough research, understanding the latest regulations, choosing the right professionals, and planning for long-term comfort and value.
Whether you’re building for your family or creating an income-generating property, partnering with an experienced builder like Kurmond Homes ensures you avoid costly mistakes and enjoy peace of mind. With custom designs, compliance support, and premium inclusions as standard, Kurmond takes the stress out of duplex construction.
