Sliding sash windows originated in Europe in the 13th Century however calling them windows was perhaps a bit of a stretch as in this period they were no more than vertical sliding wooden shutters. 300 years later, by the end of the sixteenth century they had evolved into a form we would recognise today as a beautiful traditional timber sash window.
The original windows of this period consisted only of vertical shutters with sliding timber. 16th Century sash windows were also glazed and were able to slide horizontally. It was around the mid 17th Century that the original design was superseded in France, with the French introducing vertical sliding sash windows. It has been noted that these windows were safer to use in staircases and passageways, as opposed to the casement windows that open inwards and could cause impediment to the residents of a building.
It is believed that throughout the post restoration age after the aristocracy returned from France, that the sophisticated style of the upright sliding sash window moved across the Channel towards England. The Queen Mother, Henrietta Maria, was believed to receive the first installation of a fully glazed vertical sliding window. This is believed to have occurred after she returned from France along with her staff, of which there were French joiners, and this influenced the refurbishment to the London based Somerset House. Years later, it was Ventrolla who renovated these very windows.
The improvement to the sash windows, including the introduction of the counter balance, cannot be pinpointed to a particular time exactly and there are many theories about this. Some believe it was first invented in England, where it progressed from the inventive vertical slider, into one that was glazed with 250mm x 250mm glass. With the addition of the solid glazing bars (40mm or more), the windows were extremely heavy and difficult to open.
The counter balance feature was believed to have been initially used for doors and this is supported by the documented evidence “Office of Works Account 1663”. It revealed that lines and weights were fitted to different doors in the buildings at Whitehall. It didn’t take long for this system to transfer over to include its use in sash windows. The documented evidence also reveals that Thomas Kinward, Master Joiner, made changes to the sash windows of the Queen's private apartment, by installing pulleys and lines to the sash windows in 1669, at Whitehall, although no specific mention of any counter weights has been noted.
The sash windows that were installed to the property belonging to the Duke and Duchess of Lauderdale, Ham House in London, showed confirmation that the windows were in fact, counter balanced. This installation occurred in 1672, and it was again, Thomas Kinward and Christopher Wren that placed their signatures on the accounts.
There was never any claim made to the invention of the counter balance system and there is no record of it ever having been patented. In the early development of sash windows with weights, the windows were framed by solid oak and there was a groove that had been cut to accommodate the weights. The top sash would not open and was in a fixed position, and it was only the bottom sash that opened. A short time later, there was a new development called the boxed frame. This frame was sectioned and its purpose was to hide the weights and enable them to go past each other easily.
New developments now showed that there were less panes and thinner glazing bars. When the duty on glass was removed in 1845, the price of the glass fell dramatically, and then the panes developed into larger panels, and the windows only contained two panes per sash. It differentiated the wealthy from the poor, to only have a single pane for each sash! Extra support for the glass came in mid 19th Century, when horns were introduced.
The Great Fire of London which started at the bakery of Thomas Farriner on Pudding Lane in 1666 played a surprising role in sash window design. Building regulations were drastically overhauled after the devastation in the hope of reducing the risk of fire and its rapid spread through the city.
One such regulation stipulated that timber window frames should be recessed behind the outside stone or brick facade, leading to the development of Georgian architecture which is widely held to be the most beautiful period of design.
It wasn’t just fire that pushed forward the sash windows evolution. Fashion and vanity played their part. In the space of 50 years from 1696 the Window tax and Glass tax were both introduced. The glass tax stopped anyone other than the very rich from having large panes and so the trend for multiple small panes of glass remained. A sign of wealth was to have large windows with a single pane of glass per sash!
As glass production technology advanced and the various taxes repealed, larger panes became available to everyone, this in itself lead to one of the most recognisable features of a Sash Window, the “horns”.
As the panes became larger and heavier the frame needed extra support and so sash horns started to appear at the corners to reinforce the widows. The horns were often carved in unique styles and have become one of the hallmarks of a traditional timber sash window.
Ventrolla has been well respected since renovations began in 1984 when they first opened their doors. They have been involved in the renovation and performance upgrade of many sliding sash windows ever since, earning themselves a place in modern history as the leading authority and market leader in the renovatin of original sash windows.