Steps To Calculating The Cost Of A Granny Flat


Do you need the perfect granny flat solutions? Are you considering extending your home to have more living space? Do you want a home office space? Or does a family member need an independent living space? If you answered yes to any of these questions, you probably considered building a granny flat. The next question is cost. And the table below offers a realistic estimate of what you can expect in terms of the price range when building a granny flat. 

Granny Flat Style  Price Range
A single-bedroom granny flat   $150,000 – $200,000
A two-bedroom granny flat   $250,000 – $300,000
A three-bedroom granny flat $300,000 – $350,000
A two-storey granny flat    $280,000 to $320,000

What is a Granny Flat?

Don’t get it twisted; a granny flat isn’t some boring living space created purposely for a grandmother. A granny flat is a self-contained, detached living space built for independent and complete living. Of course, you can build a granny flat for your ageing family member, but you can also build it as a home office or a living space for private use. You can build a granny flat as a simple, low-budget living space to rent out as an extra income stream. Regardless of the purpose behind your granny flat, it should be detached from your main home and have its own outdoor space. 

What does it cost to build a granny flat?

Now that you know what a granny house is, it’s time to talk about how much you can expect to spend on it. The actual cost will depend on some things. First, why you want to use the flat will determine how much you will spend. Secondly, the quality of materials you use combined with the flat style or design will also affect the cost. 

Custom-built granny flats vs. flat packs vs. kits

Regarding design or style, granny flats come in custom-built kits and flat packs. And you can choose any of them, depending on your preference. However, kits and flat packs are pre-cut and will limit you in window sizes and doorways. A custom build has no limits, but you may have to spend more, depending on your preferred design. 

Sizes and Price Ranges

  • 1 bedroom ($150,000 – $200,000)
  • 2 bedrooms ($250,000 – $300,000)
  • 3 bedrooms ($300,000 – $350,000)
  • 2-storey ($280,000 – $320,000)

Other costs to consider – inclusions + exclusions

You can expect to spend on other expenses such as landscaping, certification and council costs, plumbing and electrician works, labour, certifier costs, etc.  

Do I need council approval to build a granny flat?

Subject to set criteria, you can build a granny flat without needing traditional council development approval. However, you must ensure that your building meets all required development guidelines. Doing this will help you legally own your granny flat without the council getting directly involved.

Will a granny flat increase the value of my home?

A granny flat can add value to your property with its extra living space and amenities. You can also turn it into an extra source of income by renting it out to tenants. However, the size, location, construction quality, and design can determine how much extra value your property will get.  A granny flat is always worth it. And when compared to your potential investment returns and benefits, their prices are relatively low. The most important thing is to work with an experienced and trusted builder to ensure that you get value for money. 


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