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Hardwood double glazed sash windows

We can make double glazed hardwood timber sash windows to fit within your original box sash frame. New hardwood double glazing will increase the thermal performance of your sash windows and reduce noise pollution while maintaining the traditional character of your property.
Hardwood double glazed sashes

Is this for you?

  • Are your windows single glazed?
  • Do you want to improve the thermal performance?
  • Do you get condensation?
  • Are they old and in disrepair?
  • Do you want better sound-proofing?
  • Do you want to replace but keep the traditional character of your property?
Services hardwood double glazing


  • Replacing the sashes without replacing the boxes is a more cost-effective solution and less disruptive than replacing the whole window.
  • A double glazed sash will provide improved thermal performance, will retain heat and reduce the noise level.
  • Our new sashes will replicate the original window keeping the character and architectural identity of your property.
sash window renovation

How do we do it?

We make new timber sashes out of Sapele or Accoya, both of which are incredibly durable. We then fit into the existing boxes that we fully restore. 

Replacing the sashes without replacing the boxes is a more cost-effective solution and less disruption than replacing the whole window. 

We always take great care to ensure that the new double glazed sashes sympathetically replicate the originals, in terms of style, pane configuration and matching any horn or molding detail.  

On-site our team of window fitters will strip back the sash box frames to wood, they will repair any rot and replace hardwood cills if required. 

Then the boxes will be painted to finish coat using The Little Green Company paint. Once the boxes are ready, we will install new pulleys, new lead weights and then fit the new double glazed sashes incorporating a draught-proofing system. 

Finally, we provide new security locks and window furniture. 

If you are looking to improve the thermal performance of your sash windows and reduce noise pollution then our workshop in West London can make double-glazed timber sashes to fit within your original box sash frame. This is a more cost effective and less disruptive process than replacing the whole of your sash window.

Our skilled craftsmen take great care to replicate the style and detail of your existing sashes so that they maintain the traditional character and architectural identity of your property. The thickness of the double glazed unit that is fitted depends upon the width of your existing sash box. In most cases a specialist 12mm ‘restoration unit’ is used that encompasses an inert gas within the unit and a pane of low-emissivity glass, which reflects heat back into the room.

All of our new timber double-glazed sashes are finished with a range of traditional sash furniture and installed with the added benefits of our specialist Draught-Proof System.

Double glazing case studies

We replaced the old UPVC windows and reinstated original timber sashes to replicate the originals in this beautiful Kingston property

Thirteen new Accoya sash windows were fitted in to this beautiful period property in Twickenham as part of a full house renovation

See photos of this new double-glazed sash window project in East Twickenham by SashWise.

We installed new double glazed sash windows into this beautiful Victorian property in Teddington.

We installed new Accoya double glazed sashes into five windows into this lovely Teddington property. Increasing thermal performance and insulation. Plus - no more rattles!

We completed a new double glazing job at a Victorian house in Teddington involving installing five new double glazed sashes into the home.

SashWise fitted new Accoya double-glazed sash windows into the original sash boxes at this beautiful Edwardian detached townhouse in Hampton.

We installed 5 x new double glazed sashes into this pretty Victorian home in Kingston upon Thames.

We installed 14 new hardwood double glazed sashes into this stunning Victorian house in Kingston.

The original sash windows had been removed from this beautiful Victorian cottage in Twickenham. Our client wanted the windows changed back to their original style.

Our client completely restored the property and wanted to replace the windows with a more robust solution, keeping the original features in the windows.

We replaced the original single glazed windows in this beautiful Victorian House in Teddington with new hardwood double glazed sashes.

Client testimonials

Our other services

Georgian sash window

Full restoration

We will completely and sympathetically restore the windows, so they will look like new without losing any original features.

Sash window draught proofing

Servicing and draught-proofing

If your sash windows are jammed or broken, this service will get them working smoothly again

Hardwood sash window

New hardwood sash boxes

We can supply and fit new hardwood sash boxes complete with double glazed sash windows that replicate the originals.