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Sash window double glazing

Preserving historic window frames

Contact us Preserving historic window frames

Sash window renovation

Window renovation
Renovate your windows instead of replacing them

We renovate old box sash windows. Thanks to new materials available; glass, sealants, modified timber, sash window restoration is a cost-effective alternative to full window replacement. It saves time, money and the aesthetics of historic windows.

The sash window double glazing and draught-proofing eliminates draughts and improves thermal efficiency and comfort.

All this work also reduces noise pollution and energy bills.

What are the main advantages of our sash window preservation solutions?

2 solutions; wooden frames restoration and sash window double glazing offer an aesthetic and economical renovation of wooden windows:

  • Sutable for Grade 2 listed properties: windows will look identical without any loss of glass surface!
  • Economical because our intervention is fast and requires relatively little raw material.
  • We only use wood.
  • A renovated and insulated window, not only thanks to double glazing, but above all thanks to several types of seals placed in a groove (professional method) in the sashes and the frame.
  • Energy savings and comfort from the very first night of the work.

Sash window preservation examples



My windows are very rotten, can they be repaired?

Wooden windows that have not been maintained for years can look so old that you might start thinking they can only be replaced with new ones.

However, in 95% of cases, this is only in appearance as it is only the faded and cracked paint, the badly degraded putty around the panes and possible rotten lower parts of the window that may be damaged or broken, but most of the wood frame is still solid and has retained all its strength and structure underneath this layer of wear.


We renovate or replace all damaged parts of the sash window, both on the sash and on the box frame where the pulley and cords mechanism is hidden. The exterior side of the window is refurbished and pre-painted.

How to clean and treat old metal window furniture?


1. Unscrew the metal parts of the window: fastener, lock keep, security hook fastener, sash lift, arm stay.
2. Brush them with a wire brush.
3. Treat the rust with rust remover or with paint remover liquid.
4. After any liquid rust or paint remover allow to dry furniture in the open air.
5. Repaint with anti-rust paint or just polish if the window furniture is made of brass.

Will my sashes take the additional weight of double glazing if they previously were single glazed?

Yes. The double glazing units are two times heavier than a single 4mm pane glazing but even old sashes can take this additional weight and still be able to operate (open and close) properly.


During the sash window double glazing process, we repair any rot and make sashes stronger as well as add more weight (Approx. 30%) to pulley mechanisms.

How to fill-in the old hole from screw in wooden windows?

1. Remove the screw that turns in the hole.
2. Enlarge the hole with a drill.
3. Glue and insert a wooden dowel into the hole.
4. Let the glue dry.
5. Cut the dowel flush with the hole with a levelling saw.

Sash window double glazing work in partnership with