Noise attenuation for homes under flight paths: what's usually needed

Resonate Consultants · 10 October 2026 · 7 min read

Keeping aircraft noise out of a house is mostly about the building envelope: the glass, the doors, the roof and ceiling, the walls, and how the house gets fresh air with the windows shut. This guide covers what usually changes in a design near an airport, and why.

Aircraft noise behaves differently from traffic noise. It comes from above, so the roof matters as much as the walls. Near an airport it carries a lot of low-frequency energy, the deep rumble of jet engines, and low frequencies pass through lightweight materials more easily. That's why a window that does well against road noise may not be enough under a flight path.

Start with how much reduction each room needs

Under the Australian Standard for building near airports, AS 2021, every room gets its own target. The aircraft noise level at the site is worked out first, then each room needs to bring the loudest typical flyover down to an indoor level: 50 dB(A) for bedrooms, 55 dB(A) for other living spaces and 60 dB(A) for bathrooms and laundries. The difference is the aircraft noise reduction (ANR) that room's walls, windows, doors and ceiling have to provide together. There's more on how this works in What is AS 2021?

So the answer to "what do I need?" depends on the site and the room. A bedroom on a site with a design noise level of 75 dB(A) needs 25 dB of reduction. On a site at 85 dB(A), the same bedroom needs 35 dB, which is a very different building. Rooms with big windows, raked ceilings or lightweight walls need more from every element than a small bedroom with one window under a flat ceiling.

One thing holds everywhere: the reduction only works with windows and doors shut. An open window lets most of the noise straight in.

Windows and glazed doors

Glass is almost always the weak point, so it's usually where the biggest upgrades go. A few things decide how well a window blocks noise.

The glass

Heavier glass blocks more sound, and laminated glass (two panes bonded with a plastic interlayer) does better than plain glass of the same weight. Acoustic laminated glass uses a softer interlayer that does better again. For higher reductions, double glazing with a wide air gap, or a secondary window fitted inside the main one, is the usual answer.

Standard double glazing sold for energy efficiency is a common trap. With thin panes and a narrow gap it's built for heat, not sound, and against low-frequency aircraft noise it often does no better than a single thick laminated pane.

The frame and seals

A window is only as good as its weakest gap. The rating that counts is the tested rating of the whole window, frame and seals included, not the glass on its own. Sliding windows and doors are harder to seal than awning, casement or fixed windows, which press onto compression seals when closed.

The size

More glass lets in more noise, so the rating a window needs goes up as the window gets bigger relative to the room. A bedroom with a wall of glass facing the flight path is the hardest case there is. Sometimes the cheapest fix is a smaller window.

As a rough guide to sound insulation ratings (Rw, a single-number lab rating where higher is better):

AS 2021 itself warns that lab ratings overstate what's achieved on site, and the higher the rating, the more it suffers from small gaps and poor installation. Acoustic windows are also heavy. They need hardware and fixings rated for the weight, and secondary windows take up room inside the reveal.

Roof and ceiling

Because aircraft noise arrives from overhead, the roof and ceiling carry a lot of the load, especially in single-storey homes and top-floor rooms.

• Roof form. A pitched roof with a roof space above a flat ceiling performs much better than a raked or cathedral ceiling that follows the roof line. The roof space acts as a buffer. AS 2021 makes this point directly.
• Ceiling lining. A heavier ceiling (thicker or multiple layers of plasterboard) with insulation batts above it is the standard upgrade.
• Roof material. Tiles are heavier than sheet metal. Metal roofs often need an insulation blanket under the sheeting as well as a better ceiling.
• Skylights and roof windows. These need acoustic glazing like any other window, and a light well needs lining.
• Downlights. Recessed downlights leave holes in the ceiling, and AS 2021 warns of fire risk where downlights sit against insulation. It recommends against recessed downlights where the ceiling is close to the roof. Electrical work around insulation has to follow AS/NZS 3000.

External walls

Brick, brick veneer, concrete and blockwork walls usually perform well, and often need no upgrade. Lightweight walls, such as fibre cement, weatherboard or other cladding on a stud frame, may need insulation in the wall cavity, extra or heavier plasterboard inside, or linings mounted on resilient battens or clips so sound doesn't travel straight through the frame. Penetrations through any wall (meter boxes, pipes, vents) need sealing.

External doors

Hollow-core doors and lightweight glazed doors let a lot of noise through, mostly around the edges. The usual upgrade is a solid-core door with acoustic seals around the frame and an automatic drop seal at the bottom. Glazed doors need laminated or acoustic glass and a well-sealed frame. Large stacking or sliding doors to a living area are often the hardest element to get right.

Floors

Floors only matter when they're exposed. A suspended floor over an open subfloor, or a room built over a carport or open undercroft, is another path for noise and gets treated like the other elements.

Ventilation and air conditioning

If the windows have to stay shut to meet the standard, the house still needs fresh air. AS 2021 says ventilation should then be designed on the basis that windows and doors can't be opened, using mechanical ventilation or air conditioning that complies with AS 1668.2.

• A split system cools a room but doesn't bring in outside air, so on its own it may not be enough. A ducted system with a fresh air intake, or a dedicated ventilation system, usually is.
• Every duct or vent to the outside is a path for noise. Outdoor air intakes, bathroom exhausts and rangehoods need acoustically lined ducting or attenuated vents, and backdraft dampers where they're fitted.
• Ducts running through a roof space need detailing so noise doesn't travel along them into the rooms below.
• The system itself has to be quiet. A well-insulated house is very quiet inside, so fan and diffuser noise becomes easier to notice.

AS 2021 also notes that houses sealed up and left closed for long periods can develop damp and mould. A timed ventilation cycle helps, and the standard mentions one hour in every 24 working in Sydney.

The small gaps that undo the rest

Sound gets through any gap air can get through. Check these on every design:

• Wall vents, whirlybirds and roof vents
• Chimneys and flues, which need a damper or sealing
• Letterbox slots and pet doors in external doors
• Gaps around window and door frames, and around pipes and cables
• Ceiling access hatches

Design moves that cost little

The cheapest noise control happens on the drawings, before any acoustic products are chosen.

• Put bedrooms on the side of the house facing away from the runway or main flight path. Walls and windows that face away from the aircraft receive less noise, and AS 2021 allows for this.
• Use garages, laundries, robes and hallways as buffers on the exposed side.
• Keep bedroom windows facing the flight path to a sensible size.
• Prefer a flat ceiling under a pitched roof in bedrooms over a raked ceiling.
• Plan the ventilation and the acoustic perimeter early, so ducts and plant have somewhere to go.

Renovations and existing homes

Insulating an existing house costs more than building it right the first time. AS 2021 puts this down to harder access, odd sizes that don't suit standard materials, and the need to match what's already there. Secondary glazing fitted inside existing windows is often the most practical option for older homes, and it suits heritage houses where new external windows may not be allowed. Heavy doors and windows also need to be safe to open and close, which matters more in a family home than on a spec sheet.

What a report tells you

An aircraft noise report turns all of this into numbers you can build to. It sets out the noise level at the site, the reduction each room needs, and the minimum rating for each window, door, wall and ceiling. Your window supplier can quote against those ratings, and your certifier can check them. If the design as drawn falls short, the report says which elements need upgrading.

QuietPath reports are prepared by a Resonate acoustic engineer from your drawings. Start with the free check to see the ANEF band and the council's rules for your address.