Sash windows are an important part of the heritage of our towns and cities. The character of many buildings depends on the retention of the doors, windows and other fittings which the architect designed for them. Keeping original features such as sash windows is also not just a question of taste. It can make economic sense because the windows were originally made from the highest quality wood available, and real estate agents agree that the retention of original features adds value to properties, and helps them to sell more quickly. This article explains how sash window restoration can increase the sale value of your property.
Single-hung sash windows were probably invented by the French, and copied by the British during the seventeenth century. After that introduction, the double-hung sash appears to have been invented in England, and it allowed much more subtle ventilation than in the older side hung casement windows which were prevalent in earlier buildings.
At first many windows were built using hardwoods such as oak, but as these woods became more expensive and more difficult to procure, they were replaced by softwood from fir and pine forests in North America and in the Baltic.
Many old windows remain in quite good condition because the original builders used high-quality heartwood, that is wood from the center of the tree. The modern practice is to use the much cheaper sapwood, which is rather inferior.
It is important in any repair or refurbishment to use the best quality heartwood, or if that is not available, to use sapwood which has been well treated with timber preservative. It is a myth that all softwood is poor quality. There are many excellent quality timbers available from managed forests in the UK, Scandinavia and North America, which may be expected to last for decades or even centuries.
When sash windows are being repaired it is possible to introduce modern improvements such as weather seals. These are fitted into grooves which can be machined into the sashes. They are both discreet, and effective at eliminating draughts and rattles.
Energy efficiency and noise intrusion can be improved by low E laminated glass, or secondary double glazing can be installed. It is also possible to install more modern locking devices to improve security, and safety for homes with younger children.
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