The Sash Window Consultancy claims to have come up with a solution for upgrading traditional sash windows in listed and period properties that is accepted by local authority conservation officers

In place of the usual aluminum spacer bar between the two panes of glass, the Slenderglaze sash window features a polymer spacer bar which is narrower and enables the double-glazed unit to fit into traditionally constructed window rebates without the need for timber glazing beads and stuck-on glazing bars.

The company claims the use of the spacer bar makes it difficult to detect the double-glazed unit. The cavity is filled with an inert gas to achieve the thermal efficiency needed.

Sash Window Consultancy