Traditional sliding sash

Gallery captions: Bishop Burton Conservatory, Anlaby House Estate, and the Morritt Arms Hotel dining-area bay windows and doors.

Sliding sash windows are manufactured to order, for replacement of period and heritage designs or for new builds. The page said the sashes meet British Standards for strength and weather resistance and have calculated U-values to match building regulations.

Weight-assisted sashes are the lead-weight and pulley windows found on heritage properties. The page said the windows follow the original bars, curves, horns and dimensions, and can take slimline double glazing so a conservation-area replacement can meet planning rules.

Spring-assisted sliding sash

A spring-balance opening was described as a lower-cost alternative to lead weight and pulley, with little visible difference, and without dropping the detailed recreation of an existing sash.