Phone: 02 94817443

Complying Development

In 2009, the NSW Government released the Affordable Housing State Environment Planning Policy (SEPP) which permits all residential home-owners with a property larger then 450m² (which also has a minimum 12m street frontage) to build a Granny Flat on their property if their property is considered to be complying. A Granny Flat is a self-contained small house (with a maximum living space of 60m²) which is built in the backyard of an already existing house.

With this change comes a new way of processing Granny Flat applications. Home-owners wanting to build a Granny Flat in their backyard are no longer required to obtain Council approval as long as their application meets the minimum Complying Development requirements that have been set out. For more information, click on the NSW Government Granny Flat Fact Sheet.

To save you time and stress, our Granny Flat Solutions Design Consultant can prepare and submit all the applications and documents required to the Private Certifier to obtain approval of your new Granny Flat.

If your property does not meet all the conditions required to be a Complying Development, your Granny Flat can still be approved by lodging a Development Application (DA), which can only be approved by your local Council. Once again our Design Consultant can take care of all this whole process for you and submit all the applications and documents on your behalf.

Summary of Minimum Complying Development Requirements for Granny Flats

State Environmental Planning Policy (Affordable Rental Housing) 2009


sepp1N.B. – The diagrams above show a typical residential lot and a corner lot configuration, of blocks between 450m²-600m²

Additional Granny Flat Requirements:

  • Maximum of 1 Granny Flat is permissible per lot
  • Maximum floor area permissible for a Granny Flat is 60 m²
  • Must have a 24m² courtyard space for the Granny Flat, with an area of at least 4m wide
  • Conditions may apply if building in a bushfire, flood affected or heritage area
  • For Battle-Axe blocks, an access handle of at least 3m wide is required
  • Off-street car parking for the Granny Flat is not essential

Please Note:

  • This summary has been prepared as an indicative tool to help explain the site planning requirements for a Granny Flat.
  • There are other requirements that must be fulfilled also. These are the main points to consider.
  • These requirements DO NOT guarantee approval of a Granny Flat on a property.
  • A site investigation will be required in order to determine the appropriateness of a Granny Flat on the property.
  • A Section 149 (part 2) Planning Certificate (dated 2010 or more recently) is required from your local council to ensure there are no restrictions or planning issues that affect the property.


Can I build a 2 storey Granny Flat?

Generally, the answer is YES.

The Affordable Rental Housing SEPP stipulates that Granny Flats can be built on the first floor above an existing home, as long as the height of the building does not exceed 8.5m. This also applies to building a granny flat above a garage, or building a stand alone 2 storey Granny Flat.

HOWEVER- the code stipulates that the higher the building gets, the larger the rear and side setbacks will need to be, to compensate for the increased height. Once a building exceeds 3.8m in height, then a formula applies to determine the required setbacks, as per the table below.

Lot Size (sqm) Min Side Setback Amended Side
Setback Formula
Min Rear Setback Amended
Max Rear Setback
Height <= 3.8m Height >3.8m Height <=3.8m  Height >3.8m
450-900 0.9m 0.9m + (0.25 + H/3.8m) 3m 8m max
900-1500 1.5m 1.5m + (0.25 + H/3.8m) 5m 12m
1500+ 2.5m 2.5m + (0.25 + H/3.8m) 10m 15m

H= Additional Height Over the 3.8m


Block Size is 650sqm. Granny Flat Height is 4m from natural ground at the highest point. We know that the height of the building is 200mm higher than the 3.8m, therefore the following formulas will apply:

Side Setback Formula:  900mm + 0.25x200mm = 900mm + 50mm  = 950mm side setback

Rear Setback Formula:  3000mm + 3x200mm = 3000mm + 600mm = 3600mm rear setback

NOTE: once the building reached 5.5m or higher (up to 8.5m), the rear setback can remain at 8m




We are now designing and constructing dual occupancy developments, including New Home and Granny Flat packages.

Click here for more information.


Ph: (02) 9481 7443

Or visit our SHOWROOM at:

Unit 26, 7 Sefton Road, THORNLEIGH NSW 2120