Airport Noise Contours Explained: ANEC 20-25 and Granny Flat Rules

The Australian Noise Exposure Concept (ANEC) maps long-term aircraft noise around Western Sydney International Airport and determines where NSW now allows 85 sqm secondary dwellings with attenuation. For anec airport noise contour granny flat, Updated 24 June 2026.

The NSW Government uses ANEC 20–25 for the can 2026 granny flat reversal. ABC News explains that suburbs nearest the airport remain outside the change. Tier A planning only; verify your lot on official maps.

Disclaimer: General information only. Not planning, legal, acoustic, or tax advice. Confirm contours and building requirements with NSW Planning, council, and accredited certifiers.

What ANEC measures

ANEC is a planning tool forecasting aircraft noise exposure under operational scenarios, including potential future runway configurations. It is not a single-night noise reading. Planners use contours labelled in ANEC intervals to decide compatible land uses.

The 20–25 contour identifies areas expected to experience comparatively lower noise exposure suitable for secondary dwellings when paired with attenuation measures such as double glazing specified in the can 2026 SEPP amendment.

Why contour numbers matter for housing

Noise-sensitive development faces tighter controls in higher contours. The 2020 Western Parkland City SEPP ban on secondary dwellings targeted areas where forecast noise conflicted with new bedrooms and living areas.

Restoring granny flats inside ANEC 20–25 reflects a judgment that attenuated 85 sqm dwellings can meet indoor acoustic standards while higher contours remain restricted.

Suburbs excluded despite nearby LGAs

Luddenham, Bringelly, and Badger’s Creek sit closest to WSI and stay outside the reversal even though surrounding LGAs like Penrith and Liverpool include eligible parcels elsewhere. Postcode alone does not predict contour placement.

Fairfield’s Horsley Park includes properties under the 20 ANEC corridor where council advocated for restored rights, per Fairfield City Council.

Attenuation in plain language

Attenuation measures reduce sound energy entering living spaces. Double-glazed windows and compatible construction details help meet indoor criteria tied to airport planning. Acoustic consultants and certifiers assess whether proposed designs satisfy requirements for your contour and dwelling size cap.

Do not copy standard granny flat kits from non-airport zones without acoustic review.

Relationship to general NSW granny flat rules

Housing SEPP secondary dwelling standards still form the baseline statewide framework explained in our NSW CDC vs DA guide. Western Parkland City SEPP airport overlays add constraints or, in ANEC 20–25, restored permissions.

How to check your land

Use NSW Planning spatial tools and council pre-lodgement meetings. Ask explicitly: ANEC contour, underlying zone, secondary dwelling permissibility, CDC eligibility, and acoustic conditions. Written answers beat assumptions from neighbour anecdotes.

ANEC versus measured aircraft noise

ANEC contours are planning forecasts, not a guarantee of how loud your lounge feels on opening week of Western Sydney International Airport operations. They help regulators decide compatible land uses years ahead. Indoor acoustic standards attached to the can 2026 reform aim to keep bedrooms within defined sound levels even when outdoor exposure is higher.

Why 20–25 is not “silent”

Lower contour bands still experience aircraft noise; the policy judgment is that attenuated smaller dwellings can meet indoor criteria suitable for sleeping and living areas. Higher contours remain restricted because forecast exposure is too great for new noise-sensitive housing without unacceptable indoor outcomes.

Acoustic engineers and certifiers translate contour maps into glazing specifications, ventilation compromises, and construction details. Copying standard granny flat details from non-airport suburbs risks failed certification or expensive redesign.

Working with council and certifiers early

Fairfield, Penrith, Liverpool, Camden, and Wollondilly councils each run pre-lodgement processes with different wait times. Bring contour screenshots, lot dimensions, and preliminary sketches to those meetings before signing building contracts.

Baseline statewide rules remain in our NSW granny flat rules guide. Airport overlays add a mandatory extra layer on eligible lots only.

Professional reports you can need

Some councils or certifiers request acoustic assessment reports demonstrating indoor levels for proposed dwellings in airport contours. Budget for qualified acoustic consultants early rather than treating glazing as a standard window upgrade. Reports can reference ANEC bands, dwelling size, and construction types specific to your design.

Flight path updates and map revisions

ANEC contours can be revised as Western Sydney International Airport operations mature and flight paths stabilise. Landowners who qualified in 2026 should not assume maps stay static for decades. Subscribe to NSW Planning airport updates and council notices if you own long-term in contour-affected LGAs.

Future map changes can affect resale disclosures even for existing approved dwellings. Document the contour evidence used at approval time.

Frequently Asked Questions