Renovations, extensions and granny flats near airports: do aircraft noise rules apply?

Resonate Consultants · 10 October 2026 · 4 min read

Aircraft noise rules are usually written with new homes in mind, but they catch plenty of smaller projects too. If you're extending, rebuilding or adding a granny flat inside an airport's ANEF 20 contour in NSW, here's how the rules are likely to apply.

Extensions and alterations

Whether an extension needs an aircraft noise assessment depends on how your council's clause is worded.

• In Inner West, Canada Bay and Georges River, the local environmental plan (LEP) clause lists "a substantial alteration or addition to an existing building" among the development it applies to.
• In Bayside, City of Sydney and Randwick, the clause applies to development in ANEF 20 and above that the council considers likely to be adversely affected by aircraft noise, without a list.
• In Sutherland Shire, repairs, renovations and minor alterations or additions are allowed as long as they don't reduce the building's existing noise insulation.

"Substantial" isn't defined, so it's the council's call. Adding a bedroom, a second storey or a new living area is the kind of work that usually brings the clause into play. A new kitchen inside the existing walls usually isn't. If you're unsure, ask the council at a pre-lodgement meeting.

The report generally needs to cover the rooms being added or altered. Ask the council early whether it also expects existing rooms to be upgraded.

Older and heritage homes

Many homes under Sydney Airport's flight paths are older houses in heritage conservation areas. Councils there want noise treatments that don't spoil the streetscape. The Marrickville DCP says so directly, and AS 2021 notes that new stand-alone windows aren't allowed in some heritage precincts. Secondary glazing fitted inside existing windows is often the answer, because it keeps the original windows visible from the street. Our guide to noise attenuation for homes under flight paths covers the options.

Knock-down rebuilds

A knock-down rebuild is a new dwelling, so the full rules for new homes apply: inside ANEF 20, expect to show the design meets the indoor noise levels in AS 2021. In some of the higher contours the type of dwelling you can build is limited too. In Sutherland Shire, for example, a dual occupancy can't be approved in ANEF 25 and above, even though a single house can.

Near Western Sydney International, the state's rule prohibits new homes inside the ANEF or ANEC 20 contour, with narrow exceptions. The exception for dwelling houses is written for vacant land where there was no dwelling, so talk to the council before planning a rebuild there. See Building near Western Sydney International Airport.

Granny flats (secondary dwellings)

A granny flat is a dwelling in its own right, so the aircraft noise clauses that apply to homes apply to it.

• Through a development application: in most council areas near Sydney Airport, a granny flat inside ANEF 20 needs to meet the AS 2021 indoor levels. In Sutherland Shire, secondary dwellings are prohibited in ANEF 25 and above.
• As complying development: complying development under the Housing Code and related codes can't be carried out on land in ANEF 25 or above, except for ancillary works like decks, garages, sheds and pools. A granny flat isn't ancillary, so it needs a development application there. In ANEF 20–25, the Codes SEPP doesn't spell out an AS 2021 requirement for granny flats the way it does for houses, so check with your certifier what they'll need to see.
• Near Western Sydney International: since May 2026, granny flats of up to 85 m² are allowed in the ANEC 20–25 contour in the Camden, Fairfield, Liverpool, Penrith and Wollondilly council areas, as long as they meet the AS 2021 indoor levels. The NSW Government's announcement mentioned measures such as double-glazed windows.

Granny flats are often small, lightweight buildings with big windows and a skillion or raked roof, which is close to the hardest combination for keeping aircraft noise out. It's worth getting the noise requirements before the design is fixed.

Changes of use

Turning a house into a child care centre, a medical practice or a boarding house can bring the aircraft noise clause into play even without much building work. Inner West's clause, for example, lists changes of use to residential accommodation, child care, education and health uses. Several councils prohibit some of these uses outright in the higher contours.

Decks, pools and garages

Work that doesn't add habitable rooms generally doesn't need an aircraft noise assessment. One exception to be aware of: Bayside's DCP requires the noise assessment for new homes in ANEF 25 and above to consider outdoor areas such as decks and pergolas.

Getting it right

For a small project, the report is usually short: the aircraft noise level at the site, the noise reduction each new or altered room needs, and the rating each window, door, wall and ceiling has to achieve. Our council-by-council guide lists the rules and links for every NSW council near an airport.

With QuietPath, you upload the drawings for the extension or granny flat and confirm the address, and a Resonate acoustic engineer prepares the report in days.