It's not unusual in more mature windows with the higher sash to be set in place, whilst the reduced sash remains operable. Pictured earlier mentioned: Sash window grooved out browse for draught proofing method. A router and 8mm straight flute cutter is used to Reduce a neat, precise groove. Eco-pleasant https://andersonapaiq.blogkoo.com/helping-the-others-realize-the-advantages-of-sash-window-draught-proofing-55449330