Here is some information about sash windows and a rough guide to date your sash windows in your property:
As it’s deemed that ‘eyes are the windows of the soul’, windows are arguably the soul of a building. Everyone needs light and ventilation, and so the technology of windows has been at the forefront of building developments, from stained glass set in lead to hinged wooden casements, sliding sashes, double glazing, and today we can make glass so strong it can be used as a structure in its own right.
As a result, windows can tell you a lot about a house’s history. The sash is perhaps the classic British window, consisting of two halves, set one above the other, at least one of which slides vertically (unless it’s painted shut!). The sash was invented either in Britain or the Low Countries during the middle of the seventeenth century, and in the UK it went on in use throughout the nineteenth century- a tradition of over 200 years. So how do you know if it’s an early or late sash window? The answer could help you to date the house. Well, there were some subtle changes along the way which offer useful clues.
How can you tell if a sash window is early (during their first hundred years of use) or late (the second hundred years)?
There are actually three ways to check if a sash is early or late. The first is to see whether the window is flush with the façade: if it is, it’s usually early.
In London, legislation was passed in 1709 which stated that windows must be recessed into their openings by at least four inches to help prevent fire spreading up the façade, and this rule gradually spread to other towns and cities.
The second clue is to see if there is a thick frame surrounding the sashes: this is called a sash box, made of hollow timber to contain the pulley mechanism. Up to the middle of the eighteenth century the whole caboodle was slotted into the straight sides of an opening in the wall. But in 1774, another round of fire legislation was passed, which said that sash boxes must be hidden in the thickness of the wall so that only the sliding sash frames were exposed to fire. Now, the builders of Bath already did this- but elsewhere, if there’s no sash box visible- it’s late.
The third clue is to check the size of the window panes. Smaller panes set in a 3 across x 2 deep arrangement for each sash tend to be Georgian, but advances in glass manufacture in about 1840 meant that larger panes could be made, and big sheets of glass were substituted so that many Victorian sashes hold just one or two panes.
Here is one mans brief history of the sash window, and why they have been such a huge sucess over hundreds of years:
Most probably sash windows were not 'invented' but developed from the simpler horizontal sliding sash (known today as the 'Yorkshire' sash).
They are supposed to have come from Holland in the 17th century. However, W Horman, in his Vulgaria, printed in 1519, writes: Glasen wyndowis let in the lyght ...I have seen many prety wyndowes shette with levys goynge up and down.
They were first used conspicuously at Chatsworth in 1676-1680 and then in 1685 at the Banqueting House at Whitehall, designed by Inigo Jones, where they replaced the original casements (i.e. side - hung) windows.
They became exceedingly popular; earlier windows were replaced with sashes, and sashes were used almost exclusively in new buildings, from cottages to palaces, throughout Britain and the colonies, until early this century.
This phenomenal 250-year success story is due to the many excellent qualities of the sash window. For instance, the opening of the window can be finely adjusted, down to a narrow gap at the top or the bottom or both, giving good control of ventilation with little danger of rain blowing into the room. A 'French' window or inward opening casement is very vulnerable in this respect, and would be quite unsuited to British weather.
The sash, being hung from each of its top corners, rather than from the side as with a hinged window, is less likely to distort under its own weight. This has several consequences. Less distortion means longer life: there are many sash windows still serviceable after 150 years or more. Imagine a 150-year-old plastic window!
Casement windows need wider components for stiffness. Larger casement windows need two lights (the moving parts) which necessarily meet side by side in the centare and so, from the visual point of view, give a strong central vertical emphasis. The wooden structure of the sash, on the other hand, can be made with thinner sections giving more light and a more delicate appearance, and could be vertically divided into three panes, harmonisng with the classical style and so becoming the principal feature of the graceful and elegant buildings of the Queen Anne and Georgian periods.
Sash windows are very much the victims of their longevity: that rattling, draughty but unopenable old window may well have functioned beautifully for the first 100 years of its life; but in refusing to die gracefully has become the victim of inexperienced tradesmen and heavy-handed DIYers. A new plastic window will need replacing entirely in about 20 years; in the same period a new sash window will probably only need new cords, if that.
Jacob butler