How much quieter will my home be?

With acoustic laminated glass and an optimal cavity of 100mm or more, you can achieve up to 80% perceived noise reduction — around 54dB. The exact figure depends on the noise source and your existing windows.

Why is secondary glazing better than double glazing for noise?

The wide air gap between your original window and the secondary unit is far larger than the sealed gap in a double-glazed unit. That bigger cavity is what dampens low-frequency noise like traffic and aircraft so effectively.

What glass do you use for noise reduction?

We use acoustic laminated glass — typically 6.4mm or 6.8mm — which has a special interlayer that absorbs sound vibration. We recommend the right specification based on your noise survey.

Will it help with aircraft noise?

Yes. Secondary glazing is one of the most effective treatments for aircraft noise, which is why it is widely used near Heathrow, London City and other flight paths.

Does the cavity size matter?

Yes — for acoustic performance a wider cavity is better. Where space allows we maximise the gap between the original window and the secondary unit to get the best noise reduction.

A peaceful, quiet room beside a window overlooking a busy city street

Secondary Glazing

Acoustic & Noise Reduction Glazing

Specialist acoustic secondary glazing that cuts external noise by up to 80%. The proven solution for homes near busy roads, railway lines and flight paths — for quieter bedrooms, calmer living spaces and better sleep across London and Hertfordshire.

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A period room fitted with discreet acoustic secondary glazing

How it works

The most effective way to silence external noise

Noise travels through glass as vibration. Standard double glazing has a narrow sealed gap that does little to stop low-frequency sound like traffic rumble, train noise and aircraft. Secondary glazing works differently — and far better.

By adding an independent inner window with a wide air gap and acoustic laminated glass, the sound energy is absorbed and dissipated before it reaches the room. The result is a dramatic reduction in noise of up to 80%, transforming homes on busy roads, near railways or under flight paths into calm, quiet spaces.

Why choose it

The benefits of acoustic secondary glazing

Up to 80% less noise

Acoustic laminated glass and a wide cavity reduce perceived external noise by up to 54dB.

Tackles low-frequency noise

A large air gap targets the rumble of traffic, trains and aircraft that thin double glazing misses.

Laminated acoustic glass

Specialist 6.4mm and 6.8mm laminated panes are tuned specifically for sound reduction.

Better sleep & focus

Quieter bedrooms and home offices make a real difference near busy roads and flight paths.

Thermal gains too

The same sealed cavity that blocks noise also cuts heat loss and draughts.

Keeps your windows

All the acoustic benefit with none of the disruption of replacing original windows.

The numbers

How much quieter? Glazing acoustic performance compared

Noise reduction is measured in decibels (dB). Even small numbers make a big perceived difference — every 10dB reduction roughly halves perceived loudness.

Glazing type	Noise reduction (dB)	Perceived loudness	Best for
Single glazing (original window only)	~25 dB	Reference baseline	Existing untreated windows
Standard double glazing	~30 dB	Slightly quieter	Modern replacement windows
Triple glazing	~35 dB	Noticeably quieter	New-build properties
Standard secondary glazing (4mm)	~40 dB	Significantly quieter	General noise reduction
Acoustic secondary glazing (6.4mm laminated)	~48 dB	Much quieter	Busy roads, railways
Acoustic secondary glazing (6.8mm + 100mm+ cavity)	~54 dB	Up to 80% noise blocked	Flight paths, central London

The biggest gains come from two things: laminated acoustic glass (which absorbs sound energy instead of reflecting it) and a wide air gap between the two windows. A 100–150mm cavity is the sweet spot for acoustic performance — much wider than standard double glazing can offer, which is why secondary glazing outperforms double glazing for noise reduction even though both have two panes of glass.

Transparent pricing

What does secondary glazing cost?

Secondary glazing is priced per window, and the final cost depends on size, system type, glass specification and frame finish. The figures below are typical retail ranges for installed secondary glazing units in London and Hertfordshire — every survey we provide is fixed, written and free of obligation.

System type	Typical size	Standard 4mm glass	Acoustic / thermal glass
Lift-out / fixed panel	Small (up to 0.8m²)	£350–£550	£450–£700
Horizontal sliding	Medium (0.8–1.5m²)	£450–£750	£600–£950
Vertical sliding sash	Medium (0.8–1.5m²)	£550–£900	£700–£1,200
Side-hung casement	Medium (0.8–1.5m²)	£500–£850	£650–£1,100
Bespoke bay / angled	Per bay (3–5 panels)	£1,400–£2,800	£1,900–£3,800

Prices include survey, manufacture and installation. Frame colours, hardware finish and glass specification are all included in your fixed written quote — no hidden extras.

Volume discounts available for whole-house installations (5+ windows). Many of our customers spread payments across a 2–3 month installation programme — ask us about phased works during your survey.

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How it works