This is a potted history of why some sash windows have lots of small panes of glass, were others only have just the one.
A legacy from the 17th century, the vertical sliding sash window is enjoying a resurgence of popularity in the UK and, today, is recognized as an outstanding symbol of simple and functional style. The majority of traditional sash windows are box frames in which pulleys are set and weights hung to counterbalance the sashes. A variation to the traditional weighted sash is the horizontally-sliding ‘Yorkshire’ sash which, despite the name, appears in many English counties, including Sussex, our main supply area.
In the 17th century, with glass being expensive to manufacture and only available in small sizes, an arrangement of six to twelve panes in each sash was fairly common. Over time, glazing bars became thinner and more refined and windowpane numbers often increased. This trend reached its zenith in the Regency period with beautiful and graceful window designs adorning fine townhouses across the land.
The development of plate glass affected architectural style in the mid-19th century, and many older multi-paned windows were substituted by four-paned windows while from shortly after this period, houses sported large single pane sashes of the type widely seen today.