As well as offering full replacement sash windows and timber casement windows, we can also fit new single or double glazed sashes/casements to the existing window frames, if the frames are in good enough condition to be saved.

As specialists in bespoke timber windows for period, listed and conservation properties, we can carefully match your existing sashes/casements down to the finest detail, with slimline double glazing from just 11mm thick. 

Draught-proofing and new double glazed sash windows can reduce heat loss by at least 77% when compared to single glazing. We offer a range of specialist options when it comes to double glazing for sash windows, including acoustic glass, laminated security glass and restoration glass for the authentic heritage look.

Part replacement and draught proofing sash windows is the ideal option to improve performance as well as preserve as much of the original architecture as possible. By only replacing the moving parts, it provides the most cost-effective option while minimising disruption to your property.


  • Reduce heat loss and unwanted noise
  • Eliminate draughts
  • Ensure smooth running window mechanisms
  • Improve energy efficiency
  • Reduce dirt build-up
  • Upgrade security
  • Retain the original look and character of your period property

All our double glazed timber sash windows are handmade to order in our London factory. To speak to one of our experts about the options available, or to get a quote or arrange a visit to our showroom, please get in touch.

With Timbawood, you can always expect:

  • Choice of the finest stable timbers including Accoya, Sapele and Oak
  • Specialist glazing options including acoustic glass, laminated security glass, patterned glass and slimline double glazing that looks just like single glazing
  • Choice of profiles, horns and mouldings to match your existing windows
  • High quality hardware– High security fasteners, locks and restrictors 
  • Full factory spray finish with high performance microporous paint
  • Full perimeter draught proofing
  • Full design, supply and install service

We can also reglaze or replace windows with our thermally efficient single glazing, ‘Solo‘, which is 38% more effective at thermal insulation than single glazing.  


As specialists in period, conservation and listed properties, our traditional double glazed wooden sash windows have been approved for listed and conservation properties by planning officers and architects throughout London and the South East.

Please get in touch to speak to one of our specialists about about draught proofing and double glazing for sash windows.


Can sash windows be double-glazed?

Yes, it is possible to double-glaze original sash windows in historic properties, depending on the requirements of the planning authority. We offer a range of options including slim-profile double-glazing units, which look just like single glazing, and allow the windows to retain their original charm while gaining the added benefit of improved energy efficiency.

Do you need planning permission for double-glazed sash windows?

If you own a listed building, obtaining planning permission and consent is crucial when considering changes to features like windows and doors, including the installation of double-glazed sash windows. Stringent regulations are in place to safeguard architectural heritage.

Generally, permission is granted only when the windows are beyond economical repair, such as severe rot in the sash box. Mere age or single-glazing is not considered a valid reason for change; you must demonstrate the impracticality of repairing the original historical windows.

While converting from single to standard double glazing is usually not permitted, heritage ‘slimline’ double glazing might be acceptable for Grade 2 buildings. Any new features must adhere to heritage-appropriate glazing and closely resemble the original appearance.

Can you match the style of my existing windows?

Our skilled craftspeople, based in our London factory, specialise in creating made-to-measure sash or casement windows. To ensure an exact match to your existing windows, we use your original window as a template which then allows us to replicate the style and details of the original windows with precision.

Call us for our latest offers:

0208 893 4889

To arrange a free survey or quotation, please get in touch:

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