Cost of building a granny flat

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.

Where does this pricing data come from?

All prices stated in the above article are based on FY 2016 pricing data compiled by The figures resulted from a comprehensive analysis of quotes submitted by Granny Flat Builders on the site from July 2015 to July 2016.

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 August 2016.

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