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Secondary Dwellings (Granny Flats)

Whilst commonly referred to as Granny Flats, NSW planning legislation identifies this development type as a Secondary Dwelling.

To determine if you can construct a second dwelling on your property, landowners are encouraged to apply for a Section 149 Zoning Certificate to ascertain if any planning  / development restrictions apply to their land parcels.  

The provisions of the State Environmental Planning Policy (Affordable Rental Housing) 2009  (ARHSEPP) nominate that a legal dwelling should already exist on the property.

Developer contributions ( levied under Section 94 of the Act ) apply to this development type.

Developments proposed on a lot that falls away from the street require access to an easement and inter-allotment drainage line for stormwater disposal. If your lot does not have access to an easement, you will need to negotiate with neighbouring properties to create one.

Subject to the design and type of construction proposed, there are a number of different approval paths an applicant may choose when proposing a secondary dwelling.

Development Applications for Secondary Dwellings

Should a proposal not meet the relevant complying development provisions, a development application may be submitted for a secondary dwelling under the provisions of the ARHSEPP.

In assessing a Development Application under Clause 22 of the ARHSEPP, the proposal must comply with the dual occupancy provisions of Blacktown Development Control Plan 2015, excluding any provisions relating car parking and minimum allotment size.

Secondary Dwellings as Complying Development

For a secondary dwelling to be approved as Complying Development, the proposal must comply with the provisions of Schedule 1 of the ARHSEPP.

Installing a Manufactured Home as a Secondary Dwelling

The installation of a manufactured home, moveable dwelling or associated structure requires both a development consent and approval as an activity under Section 68 of the Local Government Act 1993 (LG Act).

A construction certificate or complying development certificate should not be sought for the installation of a relocatable home, as a construction certificate is only required for building work or subdivision work.

The installation of a relocatable home is not the same as the erection of a building under the Environmental Planning & Assessment Act 1979. (The definition of 'building' in section 4(1) of the EP&A Act specifically excludes a manufactured home, a moveable dwelling or associated structure.)

Also, as a manufactured home and moveable dwelling fall within the definition of 'relocatable home' they must satisfy the relevant provisions of the Local Government (Manufactured Home Estates, Caravan Parks, Camping Grounds and Moveable Dwellings) Regulation 2005.

Conversion of Existing Structures (Garages) to Secondary Dwellings

In the interests of maintaining safe, healthy and amenable dwellings, Council is required to ensure the proposed conversion or ‘change of use’ of a garage, screen enclosure or awning to a secondary dwelling complies with the Class 1 (habitable) construction requirements of the Building Code of Australia.

Examples of matters to consider in determining if it is feasible to convert an existing structure are:

  • The ground floor slab of a habitable structure must be constructed in accordance with Australian Standard (AS) 2870, be at least 150mm above the adjacent ground level and the underside of the slab must be provided with a damp proof membrane.
  • The structure is to be provided with Termite Risk Management measures
  • Floor to ceiling heights
  • The walls of the building must have a minimum boundary setback of 900mm, and
  • The building must be provided with sufficient natural light and natural ventilation.

Whilst this is not an exhaustive list of the matters for consideration in ‘changing the use of a garage’ it is representative of the key matters to be considered in assessing the feasibility of the proposal and should an existing structure not meet any of these requirements, an upgrade of the existing structure would be required.

Please note:

Failure to obtain the necessary approvals prior to construction or erection of a dual occupancy or a secondary dwelling is an offence under NSW legislation, which carries heavy fines and the potential for commencement of legal proceedings in the NSW Land and Environment Court.

Any proposed development is subject to the submission and subsequent approval of a Development Application (which consists of architectural plans, specifications and associated documents.)

Should you require any additional information in relation to the above, please contact Council’s Information Centre on (02) 9839-6000.


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