Granny Flat & Secondary Dwelling Approvals Sydney
Secondary dwelling approvals across Sydney — CDC on qualifying lots, DA for everything else. Design, BASIX, certifier coordination end-to-end.
Contact UsNSW Housing SEPP secondary dwelling rules
The NSW Housing SEPP 2021 sets the statewide framework for secondary dwellings:
| Control | Standard |
|---|---|
| Maximum floor area | 60 m² (some LEPs allow 90 m²) |
| Minimum lot size | 450 m² (some councils 300 m² in R3) |
| Minimum frontage | 12 m |
| Eligible zones | R1, R2, R3, R4 residential |
| Approval pathway | CDC (qualifying) / DA (non-qualifying) |
Cost and timeline
| Stage | Typical range |
|---|---|
| Feasibility + concept | $500 – $1,500 |
| CDC documentation + BASIX | $2,000 – $4,000 |
| CDC approval | 2 – 4 weeks |
| DA (if needed) | 6 – 16 weeks |
| Construction | $80,000 – $180,000 · 3–6 months |
Why choose giantA
- CDC specialists — 2–4 week approvals on qualifying lots
- BASIX & NatHERS in-house — both dwellings assessed together
- Experience across all Sydney councils
- Fixed-price feasibility so you know your numbers first
Frequently Asked Questions
What's the legal term for a granny flat in NSW?
Granny flat is the colloquial name. The legal term is 'secondary dwelling' — a self-contained residence on the same lot as the principal dwelling. Under the Housing SEPP 2021, secondary dwellings can be up to 60 m² (some councils allow 90 m²) and contain their own kitchen, bathroom, laundry and sleeping area.
What's the minimum lot size for a granny flat in Sydney?
Under the Housing SEPP 2021, most councils require 450 m² minimum for a secondary dwelling. Some R1/R3 zones in growth areas allow 300 m². Frontage requirement is typically 12 m. Heritage or environmental overlays may trigger DA instead of CDC.
How much does a granny flat cost all-in in Sydney?
All-in costs (design, approvals, construction) typically $80,000–$180,000. Lower end for prefabricated units on accessible sites; upper end for custom-built detached dwellings with higher-end finishes on sloping or constrained lots.
How long does granny flat approval take?
CDC (qualifying lots): 2–4 weeks approval. DA (non-qualifying): 6–16 weeks. Construction: 3–6 months. Total from engagement to handover: 6–12 months depending on pathway.
Can a granny flat be rented out separately?
Yes — secondary dwellings can be rented to non-family members in NSW. Some councils require minimum lease terms or restrict short-term rental. Check your council's DCP for specific controls on rental use.
Can I subdivide and sell a granny flat separately?
Generally no — in NSW, a secondary dwelling cannot be subdivided from the principal dwelling. It must remain on the same title. To sell separately, you need a true dual occupancy or duplex from the design stage.
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