Box Sash Detail    

The above picture shows the horn or 'joggle'. This was introduced when float glass production allowed large panes of glass to be made. Extra strength was required in the top sash lower rail to support the weight. The inside joggle (shown) is purely decorative.

The above window is double- glazed and shows the thicker bar required to hide the 'hot melt' around a double-glazed unit. We have introduced a narrower 'duplex' bar system where the traditional look is important. (see the 'glazing bars' page

We can use traditional weights for single-glazing but spiral balances are often used for double-glazing. The photo below shows that they fit where the sash cord would normally be seen

The picture below shows one of the catches that we use. This Caldwell catch locks and also pulls the front sash in tight against the brush seal between the sashes.