Secondary glazing differs to double glazing as it contains a glass pane currently being additional to an already present device, preserving money and effort. G – Ventrolla Perimeter Sealing Procedure (VPSS). The Ventrolla Perimeter Sealing System (VPSS) comprises several draught-proofing components that work collectively to seal the whole perimeter in the sash window. https://daltonlxhpy.affiliatblogger.com/87843816/little-known-facts-about-sash-windows