More on the history of the rising sash window

Sliders of one sort or another have been with us since the dawn of time. Unglazed openings were shuttered with wood boards, and a sliding version survives to the present day as the horizontal Yorkshire Slider. As glass became available, solid boards were simply replaced with frames, and further improved over time. Simple, economical, and uncomplicated.
The invention of the rising sash will almost certainly have been prompted by the fashion among the wealthy for Palladian-style buildings where window openings are taller than they are wide. This style was introduced in the late sixteenth century but was not widely adopted. It became fashionable in the late seventeenth century, during Robert Hooke's lifetime. But whether he, or some unknown but enterprising joiner conceived the idea of counter-balancing the sashes with weights concealed in cased boxes, we may never know. The story is further confused by the fashion, from time to time, to give houses complete make-overs, throwing out the old and replacing with new. (So what's changed?)

There are clues, though, when dating a particular window, as styles and construction techniques changed over the years. This is not an exact science, however, as alterations, copies and even the possibility of downright fakes all have to be taken into consideration.

In general terms, the early sash windows were constructed with solid, plain glazing bars, perhaps relieved by a slight bevel, glazed with hand-made 'cylinder' glass. It is these imperfect panes, with their inevitable undulations, pits, and reams, that give old windows a sparkle when seen from afar, as the light is caught and scattered.

Initially the window frames were generally inserted directly into the structural opening to leave the cased box completely visible from outside. This feature on its own is not a sure sign of antiquity, as an old-ish window may be inserted in a new-ish building in just the same way. However, the cased box hiding the weights is a bulky item and it must have soon occurred to a builder that concealing the box in a rebate built into inside face of the (solid) brick or stone wall would greatly increase the amount of light for a given structural opening (and, also, solar gain on a sunny winter's day in an era without central heating).

Over the years, architects and their joiners competed to improve their designs over those of the neighbours. Frames became lighter, and glazing bars became elegantly moulded and ever slimmer, culminating in the slender lambs-tongue profile which is the ultimate development of the ovolo mould. (Many modern replacements, of course, can be instantly spotted from the far side of the room by the rounded moulding at the junctions, where the ovolo was applied by a power-router after the frame was assembled. Ugh!)

As technology produced ever-larger panes of glass, glazing bars became fewer in number, (except where they were used for purely decorative purposes) shown by the proliferation of Victorian houses with but a single vertical glazing bar. By the turn of the century glass was available in large rolled or drawn sheets, and many elegant sash windows of the early 1900s have no glazing bars at all, relying on delightful proportion for their merit, and decoration, if any, being provided by arches and
curves in the main structural components. The chief driver of this process being, as always, first-cost, bringing a fine product to the mass market.

The aim of the designer is generally to achieve the most pleasing balance of proportion and economy. Ostentatious display may be recognised in the inappropriate proliferation of glazing-bars and arched rails used simply to demonstrate the wealth of the client. Wherever you look, you should be able to recognise these features. In general, the rising sash window forms a major part of our British architectural heritage, and deserves every effort to preserve and improve it for the benefit of future generations.

Useful links:
www.supasash.com
www.rugbysash.co.uk
http://forum.expertexpert.com
www.roberthooke.org.uk