In 2009, the Heritage at Risk campaign on conservation areas raised the loss of traditional windows as a cause for concern, stating that unsympathetic replacement of windows and doors represented the number one threat to our heritage and affected no less than 83% of conservation areas.
Careful consideration should be given to the replacement of any windows in a conservation area. One such consideration and area of debate amongst conservation departments is the glazing bars or astragals as they are sometimes known and if a ‘stick on’ replica glazing bar should be accepted.
The History of the Glazing Bar
From the 16th century glazing was most commonly divided by lead in the form of diamond shaped leaded lights. From the 17th century onwards rebated timber glazing bars began to be used with the developments in the manufacture of glazing and as larger and clearer sheet glass became available. Glass was fitted into a bed of putty and pinned into place using glazing ‘sprigs’, more putty was applied to weatherproof the joint between the glass and the bars before it was painted.
Glazing bars reached their greatest elegance and refinement between 1785 and 1825 where glazing patterns in sash windows began to take the design of six over six but always in proportion with the building façade.
Early glazing bars were often around 40mm thick to support the fragile glazing of the time and were ovolo moulded in shape, as glazing improved and became lighter thinner glazing bars were introduced some as thin as 12mm and lambs tongue and gothic designs were founded.