INTRODUCTION

The Sash Windows, with their subtle proportions and elegance, was one of the most important visual elements in buildings of the 18th and 19th Centuries. By Victorian times, they was the most popular form of window. In the past fifty or so years, their popularity declined. However with the growth of a more enlightened attitude towards conservation and growing appreciation of the craftsmanship and design that went into everyday buildings of the 18th and 19th Centuries, sash windows once more enjoy a revival.

People appreciate their aesthetic and functional contribution to the house and they are now restoring and reinstating sash windows that were removed in less enlightened days.

Origins

The origins of the sash windows have been the subject of much investigation and speculation. Until recently, the general opinion tended to be that sash windows were invented in Holland in the late 17th Century. Recently, however, valuable research work undertaken by Dr Hinte Louw, of the University of Newcastle Upon Tyne, suggests that sash windows could have been invented earlier in the 17th Century in England. Another school of thought suggest that sash windows originated in France and spread to England via Holland.

The word “sash”, derived from the French “chassis” , means frame. But, however it originated, sash windows are as traditionally British as roast beef, and have become synonymous with all kinds of Georgian, Victorian and Edwardian houses.

Sash Window evolution

Georgian Sash

By the middle of the century the familiar Georgian window with six or eight panes to each sash had become commonplace.

These very early windows have chunky timber members subdividing sashes into very small panes to suit the limited size of poor quality glass which was available at that time.

Victorian Sash

As the Georgian era gave way to the Victorian, so sash windows changed as well. Partly based on improved technology (particularly in glass), but mostly on the classic Victorian desire for embellished designs, sash windows grew more ornate.

The simple lines of Georgian windows gave way to ornate architraves, window trims and stone surrounds.From the beginning of the late eighteenth century fewer subdivisions and larger, heavier glass became common.

As large panes became fashionable old sashes with multiple small panes were sometimes altered their glazing bars removed and re-glazed with larger panes of plate glass.

Edwardian Sash

The death of Queen Victoria in 1901 ushered in the new Edwardian era. For sash windows this meant a return to the simple, clean, elegant lines of Georgian windows, but often on a much larger scale.

During Edwardian times sash windows became huge-regularly floor to ceiling heights, and five foot widths.

A trend towards larger paned, smaller paned sash windows with chunky glazing bars became popular.Often windows of this period combined multiple small paned upper sash – very often with horns – with a single or two pane lower sash.

This expanse of glass was much heavier than in the earlier windows and increased stress was put on the joints. The sash horn was developed to overcome this problem. Sash horns also evolved in their design over time. No window had horns prior to 1850.

Upper sashes from this period sometimes incorporate stained glass a feature that was to remain in vogue into the 1930s.

After reigning supreme in all types of buildings from castle to croft for two and a half centuries, the sash window finally fell out of widespread use in the 1950s.

Historical Glass

Glass technology has evolved through out the historical period with many distinct types influencing the design and development of the sash window. Crown glass and cylinder glass are two processes which were continually refined. Cylinder glass was made from blown cylinders of lass cut and rolled flat on a sanded surface. After the 1830s the length of glass which could be blown was greatly improved and thickness was reduced.

It’s distinct imperfections which are characteristic of a sanded surface, bubbles and other marks which tend to be linear. Crown glass as made from a large bubble of glass being spun out by a very skilled process to form a disc of glass producing the ripple effect characteristic of the material (though sometimes hard to spot on the finest examples).

Slimlite Double Glazed units can be heat-treated to give a subtle warp to the surface to match the crown glass of yesteryear.