What are the Complying Development Standards under the NSW Codes SEPP for Secondary Dwellings?

These are the key development controls for residential complying developments in NSW, focusing on secondary dwellings.

All standards are drawn from the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 (Codes SEPP).

Local LEP/DCP standards are overridden by these state controls for complying development.

Development Type	Secondary Dwelling (granny flat)
Permissible Zones	R1, R2, R3, R4, R5 (must be on same lot as a principal dwelling)
Min. Lot Size	No state minimum (lot must already contain or concurrently build a principal dwelling; subdivision not allowed). (In practice often ≥ 450 m² in R2 zones to accommodate house + granny flat.)
Min. Lot Width	N/A (secondary dwellings are ancillary to a principal dwelling on the same lot).
Max. Number of Dwellings	1 secondary dwelling per lot (in addition to the principal dwelling).
Max. Building Height	8.5 m (generally same height limit as a dwelling house, whether the granny flat is attached or separate).
Max. Number of Storeys	2 storeys (if part of/attached to a two-storey house, or a two-storey detached studio). Most secondary dwellings are single-storey but a two-storey granny flat is allowable within the height limit.
Maximum Gross Floor Area (GFA) (All buildings on the lot)	60 m² max for the secondary dwelling itself (excluding any parking area). Also must not cause the total FSR of principal + secondary to exceed the LEP/Codes max (usually 0.5:1 in low-density zones).
Site Coverage / Landscaped Area	The combined development (house + secondary) must still meet the minimum landscaped area for the lot (same % as required of a dwelling house), effectively the secondary dwelling cannot reduce the landscaped area below the Code minimum.
Front Setback (Primary road)	Same as for a dwelling house: the principal dwelling + secondary structure must comply with the above front setback requirements. (Granny flats usually cannot be in front of the main house.) A secondary dwelling behind the house is fine (front setback governed by the main dwelling).
Side Setbacks (Boundary clearance)	If the secondary dwelling is a detached structure, it must comply with the same side setbacks as any dwelling house or outbuilding: typically 0.9 m min. from side boundaries (for up to one storey), and greater if two-storey or if encroaching the 45° building height plane. If the secondary dwelling is attached to or within the house, the side setback standards for the house apply (often 0.9 m for single-storey additions).
Rear Setback	A secondary dwelling at the rear of a lot must generally respect the same rear setback as a principal dwelling. Typically 3 m min if single-storey, or more if two-storey (to maintain privacy for rear neighbours). If backing on a lane, it can be closer as per lane provisions. If the secondary dwelling is in a detached outbuilding (like above a garage), the Code requires ≥ 3 m from rear boundary for a habitable structure (garages can be 0.9 m if non-habitable, but a granny flat triggers the greater setback).
Private Open Space (Principal private open space for each dwelling)	No explicit separate POS requirement for the secondary dwelling in the Codes SEPP, but practical design dictates some private outdoor space. The principal dwelling’s required open space (as above) must be maintained. Typically, a secondary dwelling has a small patio or courtyard – often at least 8–16 m² – to be functional. (If the lot is tight, the open space may be shared with or taken from the yard of the main house, but overall landscaped area must meet the minimum.)
Car Parking	No additional parking space is required for a secondary dwelling under state policy. (The rationale is to encourage small-scale housing. A granny flat can share the existing parking of the main house or rely on street parking.) Councils cannot impose extra parking for the granny flat in a CDC scenario.
Additional Design Rules / Notes	– Relation to main dwelling: The secondary dwelling can be detached, attached or internal to the primary dwelling. It must remain ancillary (cannot be separately titled). – Max 1 secondary dwelling: Only one secondary unit is permitted per lot, and it must coexist with a principal dwelling. – No subdivision: The lot cannot be subdivided to separate the secondary dwelling. – Principal dwelling standards: If building a new house and granny flat together, the principal dwelling must independently comply with all Housing Code standards (height, setbacks, GFA, landscaping, etc.), and the secondary must comply with Housing SEPP specs (60 m² etc.). – Design: The secondary dwelling should have a separate entry and be designed to maintain the appearance of a single house (e.g. if attached, ideally integrated). There are no specific style controls in the Code beyond standard BCA requirements.