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Granny Flat SEPP Legislation – Everything You Need to Know

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When planning to build a granny flat, there many regulations that you must adhere to. Some are set by your local Council, and some by the Government. So, what is NSW SEPP Legislation?


The State Environmental Planning Policy (SEPP) allows all residential homeowners and property investors, with a property larger than 450 square metres (that also have a minimum 12m long street frontage) to build a granny flat.


Today I will give you a detailed breakdown of the SEPP Legislation.


DON'T PAY A FORTUNE FOR YOUR GRANNY FLAT. Find out how to deal with council and build a granny flat for the lowest cost possible. Learn More.

And to make it easier! I will discuss how the SEPP Legislation can work for you when building your granny flat.


I will list what changes have been made to SEPP, and how these can benefit you.


Detailed Breakdown of the SEPP Legislation


The State Environment Planning Policies (SEPPs) are environmental planning implements which evaluate planning issues in NSW.


The SEPP aims to take power away from local Councils, in order to;

  • Prevent certain types of development in an area
  • Allow certain types of development in an area, even when the local Council forbids it.


SEPPs typically give the Planning Minister the authority to make the decisions for the types of development they relate to.


SEPP can be made for ‘the purpose of environmental planning by the State’.


To find what consent your development requires, you should:


  • First look at the zoning tables in the relevant SEPPs for your proposed area of development.


If your granny flat meets the necessary standards, it will be categorised into a development that needs (a complying development or CDC).


However, you must take note of the level of environmental assessment required. If you are located in or near an environmentally sensitive area. For example, a wetland or a bush-fire prone area. You will have different development stands you must adhere to.


You will also notice general requirements for exempt developments:


That is, some minor renovations to your granny flat don’t need approval, but there are certain provisions you must satisfy. In doing so, you can attach exempt developments to your granny flat, such as:


  • Aerials and antennas
  • Awnings
  • Balconies, decks, patios and verandah’s
  • Carports and garages
  • Driveways
  • Fences
  • Flagpoles
  • Pathways and paving
  • Privacy screens
  • Water features and ponds


How the SEPP Legislation can Work for Your Granny Flat Build


The Policy aims to provide a streamlined assessment process for complying development state-wide. As such, as long as you meet certain standards, a Council or licensed Certifier can:


  • Certify your granny flat as a complying development (CDC) without the need for a Development Application (DA).


This is certainly what most Owner Builders aim for as it will take the shortest amount of time to be approved and cost the least with council.


Generally for a CDC, the rules required to build a granny flat are that your property is:


  • Based in coexistence with another dwelling (the primary dwelling)
  • On the same title as the primary dwelling (not an individual lot in a strata plan or a community title scheme)
  • May be separate from, an extension of, or attached to, the primary dwelling.


For information on how lodge an application for a complying development, see my article:



The main benefit of using this approval pathway is that:


  • Your granny flat may be approved in a few short weeks instead of 3 months, saving time and money.


What Changes Were Made and How They Can Serve You


It is a condition of the policy that the Minister must ensure its’ provisions are reviewed at least every 5 years. On 31 July 2009, the NSW Government released the State Environmental Planning Policy (Affordable Rental Housing) 2009 (AHSEPP).


This was introduced to provide a range of planning incentives to encourage and increase the development and supply of new and diverse affordable rental housing.


As such, AHSEPP supports the building of secondary dwellings, as they are a flexible way to create a place for those who need a space of their own, such as relatives or friends.


There are no limits on rent for granny flats declared in AHSEPP.


AHSEPP further supports the development of secondary dwellings, as they have changed the regulations to:


  • Allow granny flats to be approved as a complying development (CDC)
  • Allow granny flats to be built in all residential zones, such as:
  • Zone R1 (General Residential)
  • Zone R2 (Low Density Residential)
  • Zone R3 (Medium Density Residential)
  • Zone R4 (High Density Residential)
  • Zone R5 (Large Lot Residential – with a DA only)
  • Allow equivalent zones for the local council area.


  • Please note:

AHSEPP provisions for secondary dwellings do not apply to rural zonesSecondary dwellings may still be allowed in rural zones, but this will need to be checked with your local Council. As Rural “rules” are a little different.


The next SEPP Legislation rules were released on 22 February 2014.


This saw a variety of changes to both the;

  • Exempt and Complying Development SEPP

AND (to a lesser extent)

  • Affordable Rental Housing SEPP


As a result, the Affordable Rental Housing SEPP now works more closely and in better combination with the Exempt and Complying Development SEPP.


There are a few changes that are applicable to you as a granny flat developer, some beneficial:


  • Integrated Sites are seen as One Site:

Old Rule – If you owned a piece of land which held two or more lots, the calculations for sizing and setbacks were restricted per lot.

New Rule – You can now calculate the combined lot areas, so the entire combined lot dimensions can be used to calculate setbacks.


  • Ancillary Development Attached to a Granny Flat is Allowed

Old Rule – There was a lot of uncertainty if an attached structure (i.e. a garage, shed, patio, etc.) could be approved.

Many Council’s would interpret that only ‘exempt development’ structures could be attached.

This would create issues for the builder, as it meant, for example, only a 20sqm, 3m high shed could be attached.

New Rule – You can attach complying development ancillary structures (garages, carports, sheds, etc).

These can be attached to a 60sqm granny flat.

They just must comply with general SEPP legislation i.e. landscaping, adequate drainage and reasonable heights.


  • Granny Flats and Ancillary Developments are Allowed Closer to Parallel Roads

Old Rule – Granny flats or their attachments were not allowed closer to a parallel road than its two nearest dwellings.

Meaning, if you wanted to build a granny flat in your backyard, its’ rear setback was the same distance as your neighbouring houses.

New Rule – Now, a granny flat or its ancillary developments rear setback is 3m.


  • Conversion 

Old Rule – There used to be a restriction on lot size (450sqm).

New Rule – You can now convert part of your main home into a granny flat.

The alterations to your house must be internal.

The only external modification may be an entrance to the granny flat.

But, as the changes are made to the primary home, there are no restrictions on your block size.


The next changes, the State Environmental Planning Policy (Exempt & Complying Development Codes) Amendment 2017, were released on 16 June 2017.


The difference between the old and new codes is in relation to their format instead of any significant changes to their actuality. The format is changed by the way of diagrams and tables. This is an attempt to deliver more clarity and simplify the development standards.


However, whether it resulted in better developments that accounted for the property’s features is yet to be seen.


The next changes were released in 2021, and are called the State Environmental Planning Policy (Housing) 2021.


New provisions are in Chapter 3 – Diverse Housing; Part 1 – Secondary Dwellings.


This is a good section to read if you live on bush fire prone or flood affected land, as it will specify your site requirements, and how they are different from general requirements.


These new development standards apply to all flame zones apart from the BAL-FZ.


And if building in a flame zone, you must:


  • Meet all development standards in the Planning for Bush Fire Protection.
  • Not be on land that is any way associated with grasslands.
  • Be on property that either has uninterrupted access to a public road, or a road that is looked after by Council, and built within 200m of this road.
  • Have water supply on the property that is either reticulated or suitable for firefighting.
  • Have your gas installed and looked after in accordance with AS/NZS 1596:2014; The storage and handling of LP Gas.
  • Have all gas cylinders a minimum of 10m from flammable materials, and more.


More about building in a flame zone the requirements can also be read about in our article Granny Flat Fire Rules – Understanding Fire Separation.


New developments standards for flood control lots are:

  • Complying development cannot be carried out on flood storage areas, floodway’s, flow paths, high hazard areas or high-risk areas, as certified by either the Council or a professional engineer.
  • The building cannot cause a habitable room in the new dwelling to have a floor level lower than the minimum floor level.
  • If part of the granny flat is built at or underneath the flood planning level, it must be made from flood compatible materials.
  • The granny flat must be able to endure the forces that flood waters exert, and also any debris and buoyancy, at levels that can be read about in the Flood Risk Management Manual.


For more advice, if you are planning on building in a flood zone, you can also read our blog, Granny Flat In A Flood Zone? Here Is What To Do About It.


And further new requirements are under Schedule 1 – Complying Developments for Secondary Dwellings.


This is a good section to look at if planning on building, as it refers to numerical controls, such as the below.


Lot requirements:


  • For all properties except battle-axe lots, a street frontage of at least the below is necessary:
    • 12m for lots between 450sqm to 900sqm.
    • 15m for lots between 450sqm to 1500sqm.
    • 18m for lots larger than 1500sqm.
  • For battle-axe lots, an access laneway of no less than 3m wide and 12m by 12m.


Maximum site coverage allowed of all structures on site:


  • The main home, the granny flat, and all ancillary structures on site must not exceed the below:
    • For sites 450sqm to 900sqm – 50% of the properties area.
    • For sites 900sqm to 1500sqm – 40% of the properties area.
    • For sites greater than 1500sqm – 30% of the properties area.


What are not counted as ancillary structures in the above when calculating site coverage are:


  • Access ramps.
  • Awnings, blinds or canopies that may be on the outer wall of a building.
  • Verandahs, balconies, decks, patios, terraces, or pergolas that are connected to the main home or granny flat and are not enclosed by a wall that is greater than 1.4m in height above the floor level.
  • Eaves.
  • Driveways.
  • Farm buildings.
  • Fences or screens.
  • Pathways or paving’s.
  • Rainwater tanks that are joined to either the main home or granny flat.
  • Spas or swimming pools.


Maximum floor area allowed for both your principal dwelling and granny flat:


  • The floor area of the granny flat must not be greater than 60sqm.
  • The total floor area of the main home, the granny flat, and all attached ancillary structures must not exceed the below:
    • For properties between 450sqm to 600sqm – 330sqm.
    • For properties between 600swm to 900sqm – 380sqm.
    • For properties larger than 900sqm – 430sqm.


Building heights and setbacks, which can be read about in our article here how to calculate, as these have not changed.


Landscaping and principal private open space areas, which can be read about in our blog here, as these to have not changed.


Next, they talk about how deep you are allowed to excavate on site when building a granny flat:


  • Measured from existing ground level, you can excavate to the maximum depth of:
    • 1m if located no greater than 1m from any boundary.
    • 2m if located between 1m to 1.5m from any boundary.
    • 3m if located greater than 1.5m from any boundary, or
    • 1m only, if the land is classified as Class 3 or 4 on an Acid Sulfate Soils Map or located within 40m of a natural body of water.


Finally, they talk about fill, how deep you are allowed to fill when building a granny flat. This is 1m only, measured from existing ground level.


Further Information to Find Out More About the SEPP Legislation



For further enquiries you can also:

  • Call: (02) 9228 6111
  • Email: housingpolicy@planning.nsw.gov.au

From Planning NSW for example.


Or, if all else fails, walk into your local Council or give them a call.




The State Environmental Planning Policy (SEPP) aims to provide a more efficient and simplified policy for complying development state-wide.


It takes authority from the local Councils, and by doing so, SEPP;

  • Prohibits some types of development in certain areas
  • Still allows some types of development in certain areas, even when the local Council bans it.


There have been several updates to SEPP over the years, which have worked in the favour of developers.


SEPP now lets’ every residential homeowner or property investor in NSW build a granny flat, as long as;

  • Their property is larger than 450 square metres
  • They have a minimum 12m street frontage, though this may need to be larger, depending on the size of your block.


It has been recognised that throughout NSW there is a strong need for affordable housing. This was shown in figures that had over 47,000 people on waiting lists for suitable accommodation in February 2010.


So, a lot more leniency on the development of granny flats has been allowed. They are seen to be a flexible way to create a small home for those who need a place to stay. Such as your relatives or friends.


Granny flats are now allowed to be built in most residential zones, with no limit on rent prices (depending on which state you are in). In NSW there are no restrictions.


You can even now attach complying development ancillary structures to your granny flat, including; Garages, carports and sheds, allowing for more space.


Have fun designing your granny flat – abide by the regulations of SEPP and then your imagination is the limit.