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Cost of building a granny flat

Last updated: 7th Jun 2019 → Articles  →  Cost & Pricing Guides  → Cost of Building a Granny Flat Australia

The average cost of building a granny flat is $50/hr. However, depending on your specific project requirements, the price of the job can jump to as high as $67.50/hr. Very cheap and basic pre-fabricated granny flat kits can cost as low as $10,000, excluding the cost of hook ups and professional installation from a qualified builder which will generally add at least $30,000 to the total project price, while custom granny flat homes will usually range over $120,000. 

Average values for standard 1 bed, self contained granny flats will generally range in price between $50,000 – $100,000 in Australia, including the cost of standard fittings and professional construction from a builder and licensed trades.

Where does this pricing data come from?

All prices stated in the above article are based on FY 2018 pricing data compiled by The figures resulted from a comprehensive analysis of quotes submitted by Granny Flat Builders on the site from December 2016 to December 2017.

Real Granny Flat Jobs Recently Completed on

DA approved outbuilding to granny flat conversion
James from Sydney paid $55,000 for a DA approved upgrade to existing outbuilding to granny flat, new driveway, gate and water tank.All documents already submitted to PCA for CC.
DA approved outbuilding to granny flat conversion
Arnold from Lurnea paid $12,000 for the construction of a granny flat kit home, approximately 49 square metres in length.

Factors to be considered in building a granny flat

Even though granny flats are generally considered inexpensive housing, the actual cost of building it will still be based on a variety of factors. Builders usually make several considerations including:


While granny flats are typically designed to be small spaces, they don’t have to always be like that. If the space on the property is big enough, a granny flat can have as many as three to four bedrooms. These will cost more because they will take more time and more materials to complete.


Granny flats have both standard and custom-made designs. Standard ones can come in prefabricated kits for easier installation — this makes them easier on the budget as well. These kits are usually for one to two-bedroom granny flats. Meanwhile, custom-made designs are still popular, but you’ll have to spend more money on them.

Additional tasks

This can involve things such as earthworks. Costs will likely rise if the area needs to be prepared prior to installing or building the granny flat. Site preparation can include anything from excavation to clearing any possible obstructions such as trees, bushes, and large rocks.


Requirements for building a granny flat

Before you go ahead and hire a professional to build a granny flat in your property, you should review the necessary requirements. Qualifications differ slightly from state to state, but generally they include the following:

1. The property must have a minimum area of 450m2.

2. The property must be properly zoned as “residential”.

3. The following floor space requirements must be met:

– 330m2 for an area that’s 450 – 600m2

– 380m2 for an area that’s 600 – 900m2

– 430m2 for an area that’s 900m2 or more

4. The property must have a minimum boundary of 3m at the rear and 0.9m from the side.

5. The property must have a maximum external area of 60m2.

Pricing information correct as at December 2017.

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