How Loud Is London? A Decibel Guide for Homeowners
Typical noise levels from London's roads, railways and flight paths, what the World Health Organization says is healthy indoors, and how much each type of window actually blocks.
Last reviewed October 2026 · Written by London Secondary Glazing
Decibels are logarithmic
Every 10 dB increase sounds roughly twice as loud. A 75 dB road is not a little louder than a 65 dB street; it sounds about double.
Night is what matters
The WHO bedroom guideline is about 30 dB(A) on average. Most London main-road bedrooms with single glazing sit at 50 dB or more.
Peaks wake you up
Trains, aircraft and motorbikes create short peaks. Your window needs to cut the peaks, not just the average background hum.
Typical outdoor noise levels across London
Measured at the front of the building. Your own levels depend on distance, traffic volume and how the street is laid out.
| Noise source | Typical level | Character |
|---|---|---|
| Quiet residential back street | 45 - 55 dB | Occasional cars, footsteps, voices |
| Busy London A-road at the facade | 70 - 80 dB | Constant traffic, buses and HGVs |
| Bus route with frequent stops | 72 - 82 dB | Engine idling and braking peaks |
| Overground or mainline railway (30m) | 75 - 90 dB | Short, high peaks as trains pass |
| Heathrow arrivals, west London | 70 - 85 dB | Peaks every 60 - 90 seconds on approach |
| Night-time economy streets (Soho, Shoreditch) | 65 - 80 dB | Voices, music and taxis late at night |
Want figures for your exact street? Defra's strategic noise maps show modelled road, rail and aviation noise across England.
How much noise does each window block?
The figures below are typical laboratory sound reduction ratings (Rw). The indoor column assumes a busy road outside at around 75 dB.
| Window | Sound reduction | Result indoors |
|---|---|---|
| Original single-glazed sash (draughty) | 20 - 25 dB | Road at 75 dB becomes ~50 - 55 dB indoors |
| Standard double glazing (4-16-4) | 30 - 33 dB | ~42 - 45 dB indoors |
| Secondary glazing, 100mm cavity | 40 - 45 dB | ~30 - 35 dB indoors |
| Secondary glazing, 150 - 200mm cavity, acoustic laminate | up to 54 dB | Below 30 dB indoors |
The deciding factor is the cavity. Two panes close together vibrate as one, so standard double glazing gains little over a well-sealed single pane. Moving the second pane 100 - 200mm away and using glass of a different thickness breaks that link, which is why acoustic secondary glazing is the standard fix for London homes on main roads and flight paths.
Frequently asked questions
Want to know how quiet your home could be?
We take noise readings during every free survey and recommend the cavity and glass that will bring your rooms within healthy levels.
Related Services
Noise reduction solutions for London homes.
Acoustic Secondary Glazing
Cut noise by up to 54dB with acoustic-optimised glazing.
Flight Path Noise Reduction
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Railway Noise Reduction
Block train and tube noise for quieter nights.
Secondary Glazing London
Our complete secondary glazing service across every London borough.
Soundproof Windows
Peaceful interiors near busy roads, railways and flight paths.
Thermal Secondary Glazing
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