NSW planning resource · $19

NSW Granny Flat (Secondary Dwelling) Compliance Check

Pre-lodgement check for NSW granny flat DAs. Catches the BASIX-plan mismatches, setback breaches and DCP roof-form gotchas that get owner-builders refused.

Owner-builders, homeowners, building designers and certifiers running secondary dwelling DAs through any NSW council.

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What's a 'secondary dwelling' under the Housing SEPP?

The formal NSW planning term for a granny flat is 'secondary dwelling'. They're governed by Chapter 3 Part 1 of the State Environmental Planning Policy (Housing) 2021, with the numerical standards in Schedule 1 of that SEPP. Permitted in residential zones (R1, R2, R3, R4, R5) where the LEP also permits a dwelling house, a secondary dwelling can be detached, attached, or contained within the primary dwelling.

The Housing SEPP caps the secondary dwelling floor area at 60 square metres OR 25% of the principal dwelling's total floor area, whichever is the greater (per cl 5.4(9) of the Standard Instrument LEP — see Chen v Auburn City Council [2015] NSWLEC 1379 for the parking-exclusion test). The lot must be at least 450 sqm if the secondary dwelling is detached.

The post-2024 SoE Order changed everything

Before 1 July 2024, NSW councils typically negotiated with applicants. Errors at lodgement could be fixed during assessment. After 1 July 2024, the Statement of Expectations Order capped average DA determination times at 115 days (dropping to 85 by July 2027) — and councils now refuse non-compliant DAs in days rather than amend them.

A real granny flat DA we audited (Canterbury-Bankstown DA-357/2026, 20 Dennis Street Lakemba) was refused 17 days after lodgement. The refusal letter explicitly cited the SoE Order: 'we are not able to offer opportunities to make changes to your proposal'. The reasons: BASIX commitments (hot water rating, ceiling fan, window dimensions) not visibly shown on plans; rear setback 900mm vs 3m required; combined roof with alfresco vs DCP requirement for separate roofs.

Each one of those is a small pre-lodgement design decision. Each one became a refused $4,000+ DA. Pre-lodgement compliance checking is now the difference between an approved DA and a refused one with no recourse short of an LEC appeal or full re-lodgement.

What the check covers

Our Granny Flat Compliance Check assesses 28 standards across 7 categories — every numerical threshold in Housing SEPP Schedule 1 plus the DCP residential standards that vary by council and the BASIX cross-check that catches the #1 refusal trigger.

Lot eligibility — primary dwelling on lot, residential zone (R1-R5), 450 sqm minimum, one secondary per lot
Floor area — 60 sqm cap (parking excluded), or 25% of principal dwelling per cl 5.4(9)
Setbacks — 3m rear minimum (Sch 1 cl 3(10)), 0.9m side minimum, building envelope plane
Privacy and overlooking — habitable-room separation, screening, 1.5m+ sill heights
Solar access — 3 hours 9am-3pm 21 June to neighbours' POS
BASIX cross-check — hot water rating, ceiling fan locations, window dimensions, all visibly shown on plans
Heritage / bushfire (BAL-29 max for CDC) / flood / acid sulfate soils exclusions
Stormwater drainage — connection to primary dwelling system
Parking — 1 additional space typically required
DCP gotchas — separate roof requirement for granny + alfresco (Canterbury-Bankstown DCP 2023 Ch 5.2 etc.)

The two pathways

Where every Housing SEPP Schedule 1 standard is met AND the lot isn't excluded (heritage, BAL-FZ bushfire, flood-storage), the secondary dwelling can go through the Complying Development Certificate (CDC) pathway — issued by a private certifier or council in 20 statutory days.

Where any standard is breached or the lot is excluded, the proposal goes through the Development Application (DA) pathway — merit-based council assessment under Section 4.15 of the EP&A Act. Statutory determination times under the SoE Order: 115 days reducing to 85 days by July 2027.

The Compliance Check tells you which pathway is realistically open and what each demands.

Real example

Real refusal: Lakemba 2026

DA-357/2026 at 20 Dennis Street Lakemba (Canterbury-Bankstown). Detached secondary dwelling with covered alfresco. Lodged 24 March 2026, refused 10 April 2026 — 17 days. Reasons: (1) BASIX commitments for hot water, ceiling fan and bathroom window not shown on plans; (2) rear setback 900mm vs 3m required by Housing SEPP Schedule 1 Control 3(10); (3) combined roof with alfresco — Canterbury-Bankstown DCP 2023 Ch 5.2 requires separate roofs. The applicant submitted an amended BASIX cert; council refused anyway because the amended dimensions still didn't match the plans. Each one of these is a $19 Compliance Check away from prevention.

The statutory framework

NSW secondary dwellings sit at the intersection of state SEPP, council LEP and council DCP.

Housing SEPP 2021 Chapter 3 Part 1

Cl 49-59 — secondary dwelling permissibility, definitions, floor area cap, setback (Sch 1), parking, bushfire (cl 57), flood (cl 58), Siding Spring (cl 59), CDC pathway exclusions for R5 / basements / top-roof terraces (cl 54(1))

Standard Instrument LEP cl 5.4(9)

Total floor area of the secondary dwelling (excluding parking) must not exceed the greater of 60 sqm or 25% of the principal dwelling's floor area

Codes SEPP 2008 cl 1.17A and 1.19

General CDC requirements and environmentally-sensitive land exclusions

Sustainable Buildings SEPP 2022

BASIX certificate requirements — applicable to all secondary dwellings

Chen v Auburn City Council [2015] NSWLEC 1379

Class 1 LEC appeal establishing the parking-exclusion test in cl 5.4(9) — if the garage is specifically allocated to the secondary dwelling, it counts toward the 60 sqm cap

EP&A (Statement of Expectations) Order 2024

Made under s 9.6(9) EP&A Act. Caps DA determination at 115 days from 1 Jul 2024, 105 days from 1 Jul 2025, 95 days from 1 Jul 2026, 85 days from 1 Jul 2027

Frequently asked questions

What's the floor area cap for a NSW granny flat?

60 square metres OR 25% of the principal dwelling, whichever is greater. Standard Instrument LEP cl 5.4(9) is the source. Parking is excluded from the calculation, but per Chen v Auburn 2015, if a garage is specifically allocated to the secondary dwelling it counts toward the 60 sqm cap.

Is 450 sqm a hard minimum for the lot size?

Yes for detached secondary dwellings. Both the DA pathway (Housing SEPP cl 53(2)(a)) and the CDC pathway (cl 54(2)(c)) require 450 sqm. Smaller lots are eligible only if the secondary dwelling is located within or attached to the principal dwelling.

Can I have a granny flat in R5 Large Lot Residential?

On the DA pathway yes, on the CDC pathway no — cl 54(1)(a) of the Housing SEPP excludes R5 from CDC. R5 lots typically need to use a DA.

What about subdivision — can I sell the granny flat off?

No. cl 51 of the Housing SEPP prohibits subdivision of any lot on which secondary dwelling development has been carried out. Granny flats remain on the same Torrens or strata title as the principal dwelling. They can be rented separately but not sold separately. For subdividable two-dwelling outcomes, use the dual occupancy / LRHDC pathway.

What's the BASIX trap that catches owner-builders?

Every commitment in your BASIX certificate must be visibly shown on the DA plans. Hot water system rating, ceiling fan locations, window and skylight dimensions, fixture star ratings, rainwater tank size and connections. If the BASIX cert says 'install a 800x300 bathroom window for natural light' and the plan shows a 600x300 window, the DA is refused. The cert must also be valid (3 months from issue) at lodgement.

I lost my home in a bushfire / flood. Can I build the granny flat first to live in?

Yes. The NSW Government has a specific disaster recovery pathway: where the primary dwelling has been destroyed, you can build the secondary dwelling first and occupy it while rebuilding the main house. You have a 5-year window from the secondary dwelling's first occupation certificate. A caravan or similar movable dwelling is also permitted as a temporary alternative.

What's the most common refusal trigger?

Two things. First, BASIX commitments not visibly shown on the DA plans. Second, DCP-specific roof-form rules — many councils require the granny flat and any alfresco / patio to have separate roofs (Canterbury-Bankstown DCP 2023 Ch 5.2 explicitly). Both are easy to fix at design stage, hard to fix after refusal.

Do I really need a pre-lodgement check?

Under the post-2024 SoE Order culture, yes. A typical refused granny flat DA is $4,000+ in lost fees plus delay plus the cost of preparing a fresh application. The Compliance Check at $19 catches the same issues council would. The maths is obvious.

$19 — ready when you are

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