Is My Property Suitable For A Granny Flat?


The simplest way to build a granny flat (up to 60m2) is through the Affordable Housing Scheme.  Your plans can be approved by a Private Certifier within 14 days as a Complying Development, without the need to go through the Council’s DA process.

Your property needs to meet the following criteria to be able to achieve approval through the Affordable Housing scheme for a detached granny flat.   If it doesn’t meet these criteria, you may still be able to build an attached granny flat or you may be able to have your plans approved through the Council DA process.


Site Requirements


1.  Granny flats are permitted in the following development zones that will be in your local council's LEP:



a.     Zone R1 General Residential

b.     Zone R2 Low Density Residential 

c.     Zone R3 Medium Density Residential 

d.     Zone R4 High Density Residential 

e.     Zone R5 Large Lot Residential (via development application only) 

f.    Equivalent zones for the local council area. A guide to the equivalent zones is available here.

2.  Your property size must be at least 450m2.

3.   Your property must be at least 12m wide at the location of the Granny Flat.

4.   A Battle-axe block must have an access way of at least 3m wide.

5.  Maximum floor space including: upstairs, downstairs, granny flat, garages, carports, awnings & Patios:

a.     Up to 330m2 for a block 450-600m2

b.     Up to 380m2 for a block 600-900m2

c.     Up to 430m2 for a block 900m2 +

6.  The setbacks from the boundaries must be: 

a.     3m from rear boundary (or 5m if your block is larger than 900m2)

b.     .9m from side boundaries (or 1.5m if your block is larger than 900m2)

c.     If building your Granny Flat on the front of your block, the setback from the front boundary must be the average of the setbacks of the nearest two houses.

d.     There must be 1.8m between the house and the Granny Flat.  If not, fire rated walls will be required. This can easily be achieved by using brick or fire rated cladding.

e.     If your block has parallel roads (meaning a road or laneway at the front and back) the setback is still 3m unless the nearest road to the flat is deemed as a classified road in which case the setback is 9m or the allowable setback as set out by the local council. (whichever is the lesser)

Note: A two story granny flat or addition over a garage is possible but may require larger setbacks from the boundaries.

7.  The maximum height of your granny flat will be 3.8m high (measured from lowest natural ground point to top of roof).

8.  Your property must have 25% of its surface for landscaping – garden or turf.  Half of this must be behind the main house.

9.  The granny flat must have at least 24m2 of outside entertainment space accessible from a living area.

10.  The excavation (cut & fill) for your granny flat must not exceed:

a.     1 Metre if located within 1 Meter of a boundary

b.     2 Metres if located between 1 to 1.5m from a boundary

c.     3 Metres if more than 1.5 from a boundary 

Note:  We can also build on piers to minimise excavation.

11.  Stormwater (water from the granny flat roof) must be connected to one of the following:

a.     Existing stormwater – usually gravity fed to the street

b.     An Inter Allotment drainage easement (sometimes found running across the rear of a property which slopes away from the street)

c.     If neither are available, we may be able to construct a dispersion or rubble pit

12.  Are there any protected trees on or near your property?  You must build 3m or more from the tree.  If you do have a protected tree which can’t be avoided, you can apply to the Council and may be able to remove it.

13.  You will need to go through the DA process if your property is located in:

a.     Flood zone

b.     Bush Fire Zone (Flame zone or BAL 40)

c.     Heritage or Conservation Area

Check your 149(2) Certificate to find out if any of the above applies to your property.   You may have a 149 Certificate if you bought your property recently, otherwise you can download one on-line or apply for one from your Council – usually a charge of approx. $53 applies:

Warringah Council Link 

Pittwater Council Link 

Manly Council Link 

Hornsby Council Link 

14.  A granny flat cannot be built on a property where there are already 2 or more dwellings found.  For more information please visit the NSW Government Planning & Environment Fast Track Approval Fact Sheet available here

If your property meets these requirements, plans can be drawn up for your new granny flat.   The design must follow the Australian Building Standards and have a BASIX certificate to ensure it meets the NSW Government’s sustainability regulations.  Our designers are up to date with the latest regulations and will ensure your design meets these criteria to enable a smooth build process.

You can choose one of our standard designs, have us design you a customised granny flat, or use an architect of your choice.