When a granny flat cannot go through as complying development, usually because the lot is under 450 square metres, the land is a flood control lot or bushfire prone above the code limits, the site is heritage affected, or a setback or siting standard cannot be met, it needs a development application to council and a Statement of Environmental Effects (SEE). The SEE has to show the secondary dwelling is permissible under Chapter 3 of State Environmental Planning Policy (Housing) 2021, that it sits within the 60 square metre floor area cap (or the larger percentage the LEP allows), that it meets the council’s DCP controls for setbacks, private open space, privacy and landscaping, and that the constraint which ruled out the CDC has been dealt with by a proper report. Done well, a granny flat DA in Sydney usually takes 2 to 4 months.
Key takeaways
- Secondary dwellings are permissible with consent under Chapter 3 of the Housing SEPP on land where dwelling houses are permitted, with a maximum floor area of 60 square metres or the percentage of the principal dwelling set by the LEP, whichever is greater.
- The complying development route generally needs a lot of at least 450 square metres and a site free of the code exclusions; outside that, the granny flat goes to council as a DA.
- The Housing SEPP contains non-discretionary standards, including that council cannot require additional parking for the secondary dwelling, but the DCP still applies to setbacks, open space and privacy.
- The constraint that forced the DA (flood, bushfire, lot size, heritage, trees) becomes the centre of the SEE and needs its own specialist report.
- A secondary dwelling cannot be subdivided from the principal dwelling, and the SEE should say so.
Why the CDC route fails, and what it means for the SEE
Most granny flats in Sydney are approved by a certifier as complying development under the Housing SEPP, described on the NSW Planning secondary dwellings page. The certifier has no discretion: the lot, the siting and the building either meet every standard or they do not. The common reasons they do not are set out below, and in each case the SEE has to carry the assessment the certifier could not make.
| Why the CDC is not available | Where we see it | What the SEE and DA must include |
|---|---|---|
| Lot under 450 square metres | Older subdivisions in Fairfield, Cabramatta, Lakemba, Granville and Auburn | A DCP assessment showing open space, landscaping and setbacks still work on the smaller lot |
| Flood control lot | Penrith, Hawkesbury, Fairfield, Liverpool, Canterbury-Bankstown, Central Coast lowlands | Floor levels against the flood planning level, response to the LEP flood clause, sometimes a flood report |
| Bushfire prone land above the code limits | The Hills fringe, Wollondilly, Blue Mountains, Hornsby, parts of the Central Coast and Lake Macquarie | Bushfire assessment under Planning for Bush Fire Protection 2019 with the bushfire attack level and AS 3959:2018 construction level |
| Heritage item or conservation area | Parramatta, Windsor, Camden, Campbelltown, Newcastle inner suburbs | Heritage impact statement, design response in materials and siting |
| Setback, height or siting standard not met | Narrow or irregular lots anywhere | Justification against the DCP objective for each departure |
| Tree removal or building within a tree protection zone | Cumberland, the Hills, Ku-ring-gai, Lake Macquarie | Arborist report to AS 4970-2009 |
If you are not sure which side of the line a site falls, our DA or CDC pathway advice answers that before design money is spent.
Permissibility under the Housing SEPP
The first section of the SEE establishes that a secondary dwelling is permissible. Chapter 3 of the Housing SEPP permits secondary dwellings with consent on land in a residential zone, or another zone where dwelling houses are permitted, provided there is a principal dwelling on the lot and the secondary dwelling is the only one. The SEE cites the chapter, states the zone under the LEP (for instance R2 Low Density Residential under Fairfield LEP 2013 or Penrith LEP 2010), confirms the principal dwelling is a dwelling house, and confirms there is no existing secondary dwelling or dual occupancy on the lot. It also notes that the SEPP prohibits subdivision of the secondary dwelling from the principal dwelling, which owners sometimes do not know when they buy the site.
The floor area cap and how it is calculated
The Housing SEPP caps the floor area of a secondary dwelling at 60 square metres, or the percentage of the principal dwelling’s floor area that the LEP nominates, whichever is greater. Most Sydney LEPs adopt the 60 square metre figure. The SEE must show the calculation to the SEPP definition, with the exclusions (such as a patio or carport) applied correctly. The plans, the SEE and the BASIX certificate under State Environmental Planning Policy (Sustainable Buildings) 2022 must carry the same figure. A granny flat drawn at 62 square metres is not approvable, and the SEE cannot argue it.
The non-discretionary standards
The Housing SEPP sets out standards that, if met, council cannot use as grounds for refusal, including the floor area cap and that no additional car parking is required for the secondary dwelling. The SEE should list each and state that it is met, because some DCPs still carry parking controls for granny flats that pre-date the SEPP. Everything else, such as setbacks, private open space, privacy and landscaping, remains a matter for the DCP and for merit assessment under section 4.15 of the Environmental Planning and Assessment Act 1979.
The DCP controls that still apply
Most Sydney DCPs have a secondary dwelling chapter, and the planner works through it in the usual way. The SEE should present a compliance table for:
- Setbacks from the side and rear boundaries, and from the principal dwelling where the granny flat is detached.
- Private open space for the secondary dwelling and, importantly, for the principal dwelling, which must not be left without any usable yard. On small lots in Fairfield and Cumberland this is the control that decides the DA.
- Landscaped area for the whole site after the granny flat is built, calculated to the DCP definition.
- Height and form, with single storey the norm and two-storey or above-garage forms attracting a closer look at privacy.
- Privacy between the granny flat and the neighbours’ yards and windows, and between the two dwellings on the site.
- Access from the street to the granny flat door, usually a path of a minimum width along the side of the principal dwelling.
- Stormwater, with the discharge point identified and on-site detention where council requires it for the additional roof area.
The numbers differ between Fairfield City Wide DCP 2013, Cumberland DCP 2021, Liverpool DCP 2008 and Central Coast DCP 2022, and they change, so take them from the current DCP.
The constraint report at the centre of the DA
Whatever ruled out the CDC now becomes the main event. On a flood control lot in Emu Plains, Chipping Norton or Milperra, the SEE sets the finished floor level against the flood planning level, addresses the LEP flood clause and, where council requires it, refers to a flood report on the effect of the building on flood behaviour. On bushfire prone land in Kellyville, Silverdale or the Blue Mountains, the bushfire assessment under Planning for Bush Fire Protection 2019 gives the bushfire attack level, the asset protection zone and the construction standard, and the SEE summarises it. On a heritage site the heritage impact statement does the same. The SEE should not repeat the specialist report; it should point to it and state the conclusion in one or two sentences a planner can quote.
Frequently asked questions
Can I build a granny flat on a lot under 450 square metres in NSW?
Not as complying development, but often yes by development application. The Housing SEPP permits secondary dwellings with consent on residential land, and council assesses the smaller lot on merit against its DCP. Private open space for both dwellings and landscaped area are the controls that usually decide it.
How big can a granny flat be in NSW?
The Housing SEPP caps the floor area at 60 square metres, or the percentage of the principal dwelling’s floor area that the LEP allows, whichever is greater. Most Sydney LEPs use the 60 square metre figure. Patios and carports are generally outside the calculation but the definition must be applied carefully.
Does a granny flat need extra car parking?
No. The Housing SEPP provides that council cannot require additional parking for a secondary dwelling. A DCP control that says otherwise is overridden by the SEPP, and the SEE should say so.
URBA prepares the Statement of Environmental Effects for granny flat DAs on the small, flood-affected, bushfire prone and heritage sites where the CDC route is closed, and our secondary dwelling planning service covers the pathway check first. Send us the address and the section 10.7 certificate and we will provide a fee proposal.