Ultimate guide to noise insulation for windows: valuable tips & tricks

Sound gets in through the glass and round the seal.

Sound reaches a room through a window in two ways. Some of it passes through the glass itself, and the rest comes round the frame through any gap the window no longer closes. They are separate problems with separate answers, which is why a survey looks at the frame before it looks at the glass.

Two panes of the same thickness resonate at the same frequency, so an acoustic sealed unit pairs an uneven combination instead, usually a thicker or laminated sheet against a standard one. That mismatch is the principle every acoustic glass unit is built on.

The other half is the seal. Compression gaskets and a sash that pulls tight against the frame keep the sound down to the route through the glass, which gives the glass upgrade something to work with.

The noise you have decides the answer.

Traffic on a main road, a railway, aircraft overhead, a car park at closing time: they sit at different frequencies and they do not all respond to the same fix. Low, rumbling sound is the hardest to shift and wants mass and an air gap. Higher sound, voices and tyre roar, responds well to acoustic laminated glass.

It is worth telling us which one you have, and roughly when it happens. We ask at survey because it changes the glass specification, and the glass is settled at the start of the job rather than added to it later.

What changes in the room when it works.

Sleep is the thing people mention first. A bedroom on a main road that no longer wakes you at five in the morning is the change most people are actually buying, more than any figure on a specification sheet.

The glass that quietens a room usually earns its place twice. A laminated pane is two sheets bonded around an interlayer, which also makes it a safety and security glass, and the sealed unit around it is working on heat at the same time. A window specified for noise tends to come back better on warmth and security as well.

Acoustic laminated glass is the first thing we would change.

Acoustic laminated glass is two sheets bonded around an interlayer that damps the vibration rather than passing it on. It goes into an ordinary sealed unit, so it works with whatever frame you are already choosing, and it can go into a replacement window or into a new unit made for a frame you are keeping.

Obscure, acoustic, toughened and laminated glass are specification options across the uPVC and aluminium window routes, and on replacement glass where the frame is still sound. Liniar publish 35 dB of sound reduction for the flush sash window and 37 dB for tilt and turn. Those are their figures for those systems rather than ours for your opening, and the survey is where it gets pinned down.

Check what you have got before you change anything.

Start at the frame. Close the window, run your hand round the seal, and see whether the gaskets still compress and the catches pull the sash tight. A window that shuts properly is already doing part of the acoustic job.

Then look at the glass. Single glazing, or a sealed unit with two panes of matched thickness, is the arrangement acoustic glass is designed to improve on. If you do not know what is in there, we can tell you at survey.

A sound level app on a phone will give you a rough reading. It is not a measurement anyone would specify from, but it does tell you whether one room is worse than another, and that is a useful thing to know first.

The things worth trying yourself first.

Draught-proofing strip round a sash that no longer seals takes an afternoon and does more for noise than most people expect, because it closes the route that goes round the glass rather than through it.

Heavy curtains and a thick rug work on the sound already inside the room. They absorb rather than block, so they soften what gets through instead of stopping it at the window. Worth doing, and not a substitute for the glass.

None of that is us talking you out of new windows. It is the order we would do it in on our own houses, and if it gets you far enough, that is a good result.

Secondary glazing keeps the window you already have.

Secondary glazing is a second slim aluminium window fitted inside the reveal, in front of the original. Two separate windows with a run of air between them is a different thing from one sealed unit, and the air gap is what slows the sound down. A laminated glass upgrade is offered where noise is the whole reason for the job.

It is the route where the original window stays: a listed frontage, a conservation area, or a sash worth keeping. Horizontal sliders, vertical sliders, hinged, fixed and lift-out are the five styles, in white, brown or any RAL colour matched to the reveal.

We fit this and we fit replacement windows, and we are glad to fit either. Which one suits you turns on whether the existing window is staying, so that is the question to settle first.

How to choose between the two.

If the window is being replaced anyway, put acoustic laminated glass in the specification at the start and the noise is handled as part of that job. If the window is staying, secondary glazing puts a second window and an air gap in front of it and leaves the original exactly where it is.

If you like working things out yourself, price the window on our online quote tool. If you would rather talk it through, book a survey and say on the phone that noise is the reason, because that one sentence changes the glass specification.

Where to go next.

Two routes deal with noise and we fit both: acoustic laminated glass, in a replacement window or in a new sealed unit for a frame you are keeping, and secondary glazing inside the reveal. Which one is right turns on whether the existing window is staying.

Say the word noise in the first phone call or at the survey, and the glass gets specified around it rather than upgraded afterwards.