How to soundproof windows on a noisy London street, from quick fixes to acoustic glass

London is loud. Buses on the High Road, the night tube, sirens, aircraft on the approach to Heathrow and Saturday nights outside the pub. For most homes, the window is the weakest point in the wall for noise, and the good news is that it is also the easiest to improve. This guide goes from free fixes to the upgrades that make the biggest difference.

The short answer

To soundproof a window: first seal every air gap, then upgrade the glass. The most effective options are a double glazed unit with acoustic laminated glass and panes of different thickness, or secondary glazing fitted with a wide air gap behind the existing window. Triple glazing alone is aimed at heat, not noise.

Why windows let noise in

• Air gaps. Sound follows air. A window that does not pull tight onto its seals, or an open trickle vent, lets more noise through than thin glass does.
• Thin, identical panes. Two panes of the same thickness vibrate at the same frequencies, so some sounds pass straight through.
• A narrow gap between panes. The small cavity in a standard unit does little against the low rumble of buses and lorries.

Step 1: free and low-cost fixes

1. Close the paper test gaps. Shut the window on a strip of paper. If it slides out, adjust the hinges and keeps: see how to fix a uPVC window that won't close.
2. Replace worn gaskets. Hard, shrunk rubber lets sound through. See how to replace window seals.
3. Deal with the vents. Close trickle vents at night, or fit acoustic vent covers, which still let air in. More in trickle vents explained.
4. Sash windows: fit brush pile and new beads so the sashes stop rattling. See draughty sash windows.
5. Soft furnishings such as heavy lined curtains reduce echo in the room, though they do little against noise from outside.

Step 2: upgrade the glass

Option	How it helps	Best for
Acoustic laminated glass in a new sealed unit	A special interlayer damps vibration	Busy roads, keeping the existing frame
Panes of different thickness in the unit	Each pane blocks different frequencies	A cheaper step up from standard units
Secondary glazing	A wide air gap and a separate pane	Main roads, rail lines, period and listed homes
New windows with acoustic glass	Tight new seals plus acoustic units	Frames past repair
Triple glazing	Mainly better insulation	Heat loss, modest noise gain only

Acoustic sealed units can usually be fitted into the frames you already have, the same way we replace a misted unit, so the window does not have to come out.

Step 3: secondary glazing for the worst noise

For a bedroom over a bus route, or a flat by a railway, secondary glazing is usually the strongest answer. A slim second window is fitted inside the existing one, leaving a wide air gap between the two. It suits period homes too, because the original window stays untouched, which matters in conservation areas. Our secondary vs double glazing guide compares the two in detail.

Worth knowing: noise improvements are about the weakest point. Acoustic glass in a window that does not seal, or a perfect window beside an open vent, gives disappointing results. Fix gaps and glass together.

Which room first?

• The bedroom facing the road. Sleep is where noise costs most.
• A home office facing the street.
• The room under a flight path, where secondary glazing usually helps most.

Get advice for your street

Every road is different: the rumble of a bus route needs a different answer from late-night voices outside a bar. Send us a photo of the window on WhatsApp and tell us what the noise is, and we will suggest the right glass for the frame you have, or book a free survey. Or call 07915 903485.