Soundproofing a bedroom against night flights

If you can only afford to soundproof one room, make it the bedroom. A plane you barely notice at lunchtime can wake you at 5 a.m., and the bedroom is small enough to treat properly. This guide covers the building work. Earplugs, white noise and other ways to sleep through it are in our guide to sleeping under a flight path.

How quiet a bedroom needs to be

Two figures give a target. The World Health Organization's guidelines for Europe recommend keeping aircraft noise below 40 dB Lnight outside the home at night. For the inside, the British Standard on sound insulation, BS 8233, suggests an average of 30 dB in a bedroom between 23:00 and 07:00.

Both are averages, and at night the peaks matter more. Each plane is a burst of noise, and it is the loud moments that wake people. So count the planes as well as the decibels. At Kew Green, 10 km from Heathrow, our sample report finds 11 loud planes on an average night, and each one is a chance to wake.

How much quieter can the room get?

A UK design guide for acoustics and ventilation works through a small bedroom and shows what each set-up achieves. The figures are how much lower the noise is inside than outside.

Take a plane at 75 dB outside the window. With the window ajar it reaches you at around 62 dB. Behind ordinary double glazing with the vents open, around 53 dB. With acoustic glazing and acoustic vents, around 40 dB, and with acoustic glazing and mechanical ventilation, around 30 dB.

Treat these as a guide rather than a promise. The low rumble of a jet gets through a little more easily than the traffic noise the example assumes, and a top-floor bedroom also lets noise in through the ceiling. What the table does show is how much a shut window matters, and how much the vents matter: with the same double glazing, doing without trickle vents gains 6 to 9 dB on its own.

Start with the window

With everything shut, the window is usually the weakest part of a bedroom wall. The two options that work against aircraft are secondary glazing, a second window inside the first with a gap of 100 mm or more, and acoustic replacement windows with thick, laminated panes of different thickness. Standard double glazing does little against the low notes of a jet, and triple glazing little more. Our guide to the best windows for aircraft noise compares them.

Secondary glazing suits a bedroom well: it treats one window without replacing it, and the gap can be as wide as the window reveal allows.

Fresh air with the window shut

If you need to open the window for air, the best glazing makes no difference. The room needs another way to breathe:

• An acoustic trickle vent. A typical trickle vent rates about 31 dB, an acoustic one about 44 dB. If your window has a standard vent, replace it with an acoustic one.
• Mechanical ventilation. Whole-house ventilation with heat recovery supplies fresh air through ducts, with no vent in the window at all, which is why the rows without trickle vents are the quietest. A sound-insulated single-room unit, the kind Germany's rules name for bedrooms in airport noise zones, is the smaller alternative.

Heathrow's insulation scheme fits acoustically rated ventilation for exactly this purpose, so that people do not need to open windows for air.

Check the noise of the unit itself. The ventilation guidance in England suggests continuous mechanical ventilation should not exceed 30 dB in a bedroom on its lowest setting, and Germany's rules for airport noise zones require ventilation units in bedrooms to be no noisier than the best current practice allows.

Trickle vents keep the air fresh but do not cool a room. In summer you need other ways to keep the heat out; see our guide to keeping cool under a flight path.

Seal the gaps

Sound goes straight through any air gap, and sealing them is cheap.

• Window seals. An opening window with good seals typically rates 3 to 5 points lower than the same window sealed shut, and worn seals let in more. Compressible rubber seals work better and last longer than felt.
• A loft hatch in the bedroom. US guidance for homes near airports counts a hatch in a bedroom as a significant leak and replaces it with a heavier board sealed all round.
• Holes in the ceiling. Gaps around pipes, light fittings and extractor fans open into the loft above.
• An unused fireplace. A chimney is a hole in the roof; a damper or a tight-fitting cover closes it.

Never block a vent or air brick that supplies air to a boiler, fire or stove; ask a heating engineer before changing one.

The ceiling of a top-floor bedroom

A bedroom under the loft is noisier than one with another floor above it, and a bedroom with a sloping ceiling in the roof is noisier still. Loft insulation helps a little: it absorbs sound bouncing around the roof space, and thicker insulation does better against low notes. But it does not block sound. That takes weight in the ceiling. In US guidance, hanging a layer of plasterboard on resilient bars raises a typical roof and ceiling from about 45 to 55 points on the STC scale, provided the screws are short enough not to reach the joists. Roof windows need a second pane at the bottom of the window well. Our guide to loft and roof insulation covers all of this.

The room, the bed and the furnishings

• Choose the quieter room. When planes pass on one side of the house, rooms on the other side can be up to 10 dB quieter. If you can, sleep on the side away from the flight path, with a floor above you rather than the roof.
• Move the bed away from the window. Noise is loudest close to the outside wall, so an inside wall is quieter.
• Soften the room. Carpet, heavy curtains and upholstered furniture absorb sound inside the room. A Canadian design method allows about 4 dB between a hard, bare room and a very soft one.
• Close the bedroom door. If other rooms face the flight path or have poor windows, a solid door with seals keeps their noise out.

On a budget: what to do first

1. Keep the window shut while the planes fly, and seal it. Renew worn seals and adjust the catches so the window closes tightly.
2. Sort out the air. Fit an acoustic trickle vent or a quiet ventilation unit, so the window can stay shut all night.
3. Add secondary glazing to the bedroom window, with as wide a gap as the reveal allows.
4. Seal the ceiling. Deal with the loft hatch, gaps around fittings and any open fireplace.
5. Rearrange. Move the bed to an inside wall, or swap to the quieter room.
6. Then the bigger jobs: a heavier ceiling under the roof, and acoustic replacement windows if secondary glazing is not possible.

Before paying for any of it, check whether the airport will. Some schemes are aimed at bedrooms in particular: German airports must pay for insulation of bedrooms in the night zone of their noise area, including ventilation units, and Heathrow's scheme covers windows, ventilation, loft insulation and ceilings. Our guide to airport noise insulation schemes explains who qualifies.