Road Noise in Bedrooms: Getting a Front Bedroom Back

The number that matters is the peak, not the average

World Health Organization night-noise guidance is built around events rather than averages: individual vehicle pass-bys, a motorbike, a reversing lorry. A single-glazed sash typically gives around 25–27 dB of reduction, which leaves a 75 dB pass-by arriving at roughly 50 dB inside — well above the level at which sleep architecture is measurably disrupted.

What a bedroom specification looks like

For sleeping rooms we default to the largest cavity the reveal will take, usually 100–150 mm, with 6.4 mm or 6.8 mm laminated glass room-side. Keeping the original 4 mm pane and adding a heavier laminated one deliberately mismatches the thicknesses, which broadens the frequency range covered instead of leaving a hole where both panes resonate together.

• 100–150 mm cavity where the reveal allows
• 6.4–6.8 mm laminated room-side
• Mismatched pane thicknesses
• Compression gaskets, not just brush seals

Where the rest of the noise gets in

Once the window is dealt with, the next weakest paths are the letterbox, an uninsulated loft hatch above the landing, and trickle vents in an adjacent window. We flag these at survey. There is no point specifying 47 dB glazing next to an open background ventilator.

Ventilation without reopening the noise path

Sleeping with a window open defeats the whole install. Where a bedroom relies on the window for background ventilation we specify an acoustic trickle vent, which uses a lined baffle path to admit air while holding most of the acoustic gain.