For existing Timber Joinery, the Insert service is an ideal solution and a very popular option for both plaster and timber weatherboard homes. The existing timber frames including facings, sills and internal architraves will remain, and the balance of the window is removed including sashes before being replaced with a new insert window. 
This is a very efficient option to retain the  look of existing character of the window but giving you the option of either retaining the same configuration or changing it to suit your lifestyle.
The new inserts are sealed around the edges and any mullions removed from the internal sills will be patched and sanded ready for you to paint.
Browse the AGP Glass Double Glazing Brochure to explore your double glazing options.

Where the existing windows are no longer fit for purpose or a new window is required, Twin City can manufacture an extensive range of doors and windows to suit your home and lifestyle.
Utilising a number of suitably qualified tradesman, Twin City can replace a single window or a complete house lot as you require; with the added benefit of disposing the old joinery to ensure a seamless transition to your new double glazed joinery.
Retaining the configurations or completely changing the window layout are options you will be able to consider.
A thermally broken frame is also worth considering if you want to maximise the thermal performance.