Free tool
Check your lot
Answer what you know. The result updates as you go, and every standard checked below links back to the NSW Government page it came from.
What this checks, and where it comes from
Minimum lot area
The lot must be at least 450 m² for a secondary dwelling under the Housing SEPP.
Source: NSW Planning — Housing SEPP, secondary dwellings · checked 2026-09-06
Minimum lot width
The lot's boundary with the primary road, measured at the building line, must be at least 12 m (for a lot of 450-900 m²), 15 m (over 900-1,500 m²), or 18 m (over 1,500 m²). A battle-axe lot needs an access laneway at least 3 m wide, measuring at least 12 m by 12 m excluding the laneway. FIXED 2026-09-12: this was previously stated as a flat 12 m for every lot size, which understates the requirement on larger lots and could show a fail lot as passing.
Source: Housing SEPP 2021, Schedule 1, cl 2(1)(b)-(c) · checked 2026-09-12
Maximum floor area
A secondary dwelling approved as complying development is capped at 60 m² internal floor area.
Source: NSW Planning — Housing SEPP, secondary dwellings · checked 2026-09-06
Permitted zones
Secondary dwellings are permitted in residential zones R1, R2, R3, R4 and R5. A council's own LEP may permit them in other zones as well.
Source: NSW Planning — Housing SEPP, secondary dwellings · checked 2026-09-06
No subdivision
A lot with a secondary dwelling cannot be subdivided. The result must be exactly one principal dwelling and one secondary dwelling on the site.
Source: NSW Planning — Housing SEPP, secondary dwellings · checked 2026-09-06
Bushfire (BAL)
A BAL rating between 12.5 and 29 does not rule out the CDC pathway, provided the dwelling is designed to AS 3959 for the applicable BAL. Above BAL-29, expect the DA pathway.
Source: NSW Planning — complying development / Housing SEPP · checked 2026-09-06
CDC determination time
A Complying Development Certificate is determined by a registered certifier or council against fixed standards, not a discretionary merit assessment, and can be issued in as little as 20 days. CORRECTED 2026-09-12: this previously said there is no neighbour notification — that's wrong. Neighbours within the notification area are still given a pre-approval notice (commonly 14 days in metro areas) and a pre-construction notice (7 days metro / 2 days regional) before work starts; only the full DA merit-assessment step is skipped, not notification.
Source: NSW Planning Portal — complying development / neighbour notification · checked 2026-09-12
Rules change. Every item above shows the date it was last checked against the source — if that date looks old to you, check the source yourself before relying on it. The items this tool deliberately doesn't guess at are listed on the compliance page.