Fortunately, the box frames were in sound condition so were suitable for replacement sashes. We used ultra-thin double-glazed units (slimline) and replicated the period moulds so the sashes and bars looked as close to the originals as possible. During installation of the new replacement sashes, we draught proofed and overhauled the box frames. Once the weather seal was installed, draughts were eliminated and this made a significant difference in their thermal efficiency and operating performance. The rooms were now warmer and far more comfortable, saving on winter fuel bills too. The overhauled frame left the clients with effortlessly gliding sashes and dramatically increase the lifespan of the windows. The toughened glass we use as standard on both panes of the double-glazed unit, improves safety and provides peace of mind for many years to come.