Double Glazing for Sash Windows in London

You do not have to rip out an original sash window to be warmer. Where the sashes are sound, there are two good ways to cut the cold and the noise while keeping the window — a slim double-glazed unit fitted into the existing sashes, or secondary glazing set discreetly behind them. Both are far less disruptive than a full replacement, and both are usually allowed on period and listed properties where modern plastic windows are not.

Slimline double glazing in the existing sashes

A slim double-glazed unit is only a little thicker than a single pane, so it can be fitted into a traditional sash where standard units will not go. We rout the sashes to take the unit, re-bead or re-putty them, and re-balance the window for the extra weight by adjusting the sash weights. From the street the window looks the same — the glazing bars and putty line are kept — but there are now two panes and a sealed gap doing the insulating. Where wanted, we can specify glass with a period, lightly-textured look.

Secondary glazing

Secondary glazing is a slim second window fitted on the inside, behind the original sash. Nothing is done to the sash itself, so it is the gentlest option of all for a listed building, and it is especially good at cutting noise from a busy London road. It can be made to slide or lift out so the original window still opens, and finished to sit quietly against the reveal.

Which is right for your windows?

It depends on the condition of the sashes, whether the property is listed or in a conservation area, and whether your main concern is heat or noise. Slim units keep everything in the original sash; secondary glazing touches nothing and is strongest on sound. We will look at the windows and tell you honestly which suits them — and if a window is not worth glazing until it has been repaired, we will say so.

Done alongside repair and draught-proofing

Glazing work goes hand in hand with a proper overhaul. It is usually done with draught-proofing, new sash cords and any rot repair the window needs, so you end up with a sound, warm, quiet window rather than a glazed-up tired one.

Free estimate

Tell us about your windows and where you are in London, and we will let you know the options and what they will cost. Please get in touch for a free, no-obligation estimate.