Sash Windows
TRADITIONAL PERIOD JOINERY
History of Sash Windows
Window at St. Peter Rhodes Church, Restored by Sash Window Soltutions
Some would say that the sash window dates back as far as the 13th century. But it is generally believed that the sash window came in to existence in the late middle ages when the great defensive towers and castles slowly gave way to a more settled society that allowed the building of the great houses.
Glass was only made in small pieces up to the 1800’s. The technology did not allow for the making of larger sheets of glass. For this reason the Georgian sash window was made using many small panes rather than the bigger panes like was seen in the later Victorian times and present day.
Companies like Pilkington Glass in St Helens brought about the change to the production of float glass where large sheets of glass could be made using more modern methods of glass production as seen today.
In many of the old period houses the windows were made by setting up a workshop within the house itself. In some cases evidence can be found of the tradesman leaving his mark or initials in the sash frame.
Upkeep
Window sashes and sash frames need constant up keeping over the years. Like most things in this world they have a time when they will become not suitable for use unless maintained.
This is where with the right knowledge and the right tradesman the sash windows can be retained and saved correctly.
Sash frame repairs are carried out by carefully removing the areas of rot in the frame and carefully splicing new sections of timber frame stiles or cill in to the sash window frame.
Sash repairs can be done in much the same way. In fact the sashes can be taken away if they are very bad for full sash restoration. This results in the glass being removed, paint removed and sashes repaired, sanded and primed before being re-glazed again using the original glass from the sash. Sash windows can be very discreetly draught proofed making it more energy efficient.
Restoration
Sash window restoration, sash window repair and sash window manufacturing are more widely carried out now than in recent decades.
St Peter Rhode Sash windows before restoration by Sash Window Solutions
In the 1970’s the preservation of historic streets was not given enough thought and many areas of Georgian era towns and cities were knocked to make way for more modern buildings.
A prime example of this would be the quays in Dublin. In Fitzwilliam Street Dublin a modern office block was built where a terrace of Georgian houses once stood. The new building kept a window line that tried to follow that of the Georgian windows which still survive in the houses at each end. A great view of this can be seen on the Google Earth street scape view of Fitzwilliam Street near Merrion Square
Sash Window Double Glazing
Traditionally, the structure of the sash window has not allowed the fitting of double glazing while retaining the delicate appearance of the sash detail. The double glazed units were simply too thick. 
But in the last ten years or so different types of double glazing have come to the market.
These include slender/slim units that vary from 12mm down to just 7mm in thickness. The narrow gap between the panes in these units can have a Vacuum (in the narrowest of units) and a Krypton gas or similar in the slightly wider units.
Double glazed units can now be made fine enough to fit in to the sashes that require a traditional style glazing bar. The U-value of these units can vary from 1.1 to 2.5. This allows the more traditionally detailed sashes to successfully accommodate these new type of double glazed units.
New sash windows can be made with this in mind. Essentially the weight of the average sash increases by between 30% and 50% by introducing double glazing and so the weights must increase by the same ratio.
Where a property is under a more strict conservation listing the existing glass may well have to be kept in place for future generations.
