What Is A Granny Flat? How Do You Build One?

A granny flat, an accessory dwelling unit (ADU) or secondary suite, is a self-contained living space built on the same lot as an existing home. These units provide a flexible and cost-effective solution to accommodate the housing needs of elderly family members, adult children, or tenants. In Australia, the growing interest in granny flats has led to increased construction.  

In this blog, we’ll discuss the concept of granny flats, their design, size, regulations, and the construction process in Australia. 

The Granny Flat Concept 

The concept of a granny flat originated from the need for additional living spaces to accommodate elderly family members or relatives who require assistance and care while maintaining their independence and privacy.  

Granny flats can also be used as a source of rental income or a way to provide affordable housing options for adult children, guests, or tenants. Finding a quality flat builder is the key to building the granny flat of your dreams. 

Granny flats offer a cost-effective solution for people looking to downsize or those struggling to enter the property market. For those who work from home, a granny flat can be repurposed as a quiet home office or a creative space, offering privacy and separation from the main house. 

Design and Size 

Granny flats can be designed as detached or attached structures, with the latter being an extension of the main house. Therefore, its design should complement the existing home, respecting the architectural style, colour, and materials. Functionality, accessibility, and sustainability are critical considerations when designing a granny flat. 

The size of a granny flat can vary depending on the intended purpose, available land, and local regulations. They generally range from 30 to 100 square meters, comprising one or two bedrooms, a kitchenette, a living area, a bathroom, and sometimes a small laundry space. It should have a simple, convenient layout that is easy to clean and free of obstruction. 

Considerations When Building A Granny Flat 

Constructing a granny flat requires careful planning, design, and execution. Creating a beautiful and functional granny flat that meets all your needs while increasing property value involves the following steps and key elements:  

  • Research and Planning  

Before starting construction, thoroughly assess your property, considering the size, location, and local regulations. This is best done with expert help to fully understand the project’s feasibility and obtain the necessary approvals is beneficial so all the details are covered. 

  • Regulations 

Granny flat regulations differ across states and territories in Australia. It is crucial to check the local council’s requirements before starting construction. Apply for the necessary permits from local authorities and ensure your project complies with all building codes and zoning regulations like the following:  

Finding a quality flat builder

  • Zoning: Make sure your property is zoned to construct a granny flat. 
  • Property size: In most regions, the minimum lot size for a granny flat is 450 square meters. 
  • Maximum floor area: Each state may have its floor area limit, typically ranging from 60 to 100 square meters. 
  • Setbacks: There are minimum setbacks from the main house, side, and rear boundaries, which vary depending on the local council requirements. 
  • Parking: Some councils may require you to provide an additional parking space for the granny flat. 
  • Approval process: Depending on the size and complexity of the project, you may need to apply for a development application (DA) or a complying development certificate (CDC). 
  • Location and Size  

Choose the right spot for your granny flat on your property, factoring in privacy, accessibility, and available space. The size of the ADU should be proportionate to the main house and the lot. 

  • Hiring A Contractor  

Select a reputable contractor with experience in granny flat construction. Review their portfolio, check references, and obtain a detailed contract outlining the project scope, timeline, and costs. 

  • Budgeting 

Consider factors like design complexity, materials, labour, and permit fees when estimating the construction cost. Shop around for quotes from builders and suppliers to ensure you stay within your budget. 

  • Functionality 

Plan the layout with the end user in mind, whether for an elderly parent or a tenant. Prioritize accessibility, ease of movement, and functionality. Some aspects to consider because of aesthetics and functionality are the following:  

  • Open-plan living: An open-plan area combining the kitchen, dining, and living room can make the granny flat more spacious and inviting.  
  • Smart storage solutions: Incorporate built-in storage options, such as wall cabinets, shelves, and under-bed storage, to maximize space.  
  • Universal design: Implement universal design principles, like wider doorways, bathroom grab bars, and zero-threshold showers, to make the granny flat accessible to all ages and abilities.  
  • Energy efficiency: Add energy-efficient appliances, insulation, and windows to reduce utility bills and minimize the environmental impact. 
  • Aesthetic Appeal 

Research for a cohesive design that complements the main house and will increase the attractiveness of the granny flat. Consider materials, colours, and architectural styles that blend well together. 

  • Construction

The contractor will execute the construction process, which typically includes the following: 

  • Preparing the foundation, ensuring proper drainage, grading, and soil compaction. 
  • Laying the foundation – either a concrete slab, pier and beam, or crawl space, depending on local codes and preferences. 
  • Constructing the walls, floors, and roof framing, 
  • Installing roofing materials, such as shingles, tiles, or metal roofing,
  • Exterior finishes. Applying siding or other exterior finishes, windows, and doors. Choose exterior materials and colours that complement the area, and
  • Installing insulation, drywall, flooring, plumbing, cabinets, electricals, painting, etc. 


A granny flat is an excellent addition to an existing property because it can house a family, be leased for added income, and function as an auxiliary office. If you are contemplating building granny flats, you should be aware of the tips discussed above. By doing so, you can make informed decisions and avoid construction issues in the long run.

Khuwalid Khalid
Khuwalid Khalid
Contact at Khuwalid.khalid@gmail.com