The Box Sash Workshop

If you look at any traditional Georgian, Victorian, or Edwardian building today, the chances are that it will incorporate timber box sash windows. Vertical single and double hung sliding box sash windows came into wide spread use in the later half of the 17th century, before that period most windows would be casement windows with the glass held in place by lead.

The development of the timber box sash window went hand in hand with the improvements within the glass making industry. Leading up to the 17th century only the wealthiest of home owners could afford "crown glass" or "quarries" as they were known. Early box sash windows of the second half of the 17th century were bulky affairs with wide glazing bars and muntins to support the thick crown glass panes available at the time.

With the development of cylinder glass in the 18th century, glass became cheaper to buy, thinner in size, and was also available in larger sizes. This allowed for more elegant frames and sashes, which in turn promoted an elegant light filled and classic elevation to the building.

Of course as glass panes became larger, more strength was required to support the weight of the sashes, and around the middle of the 18th century horns or "joggles" became a feature, offering more support at the meeting rails.

All double and single hung box sash windows work in the same way. Each sash slides vertically within the box frame, they are counter balanced by lead or cast iron weights via sash cord and pulleys.

As a great number of period houses are either listed or in conservation areas, care must be taken and advice must always be sought from the conservation officer of the local district or borough council, he or she will be able to offer a wealth of advice on conservation and restoration.