The windows in our apartment are atrocious. The landlord put new windows in a few years ago, but apparently didn’t bother to apply weatherstripping or caulk where the sashes meet the inside of the wood frame.
Since we’re just renting, I bought some 3/4 weatherstripping and the plastic insulation sheeting to seal up the windows this winter. Last year, I only used the plastic, and there were a few instances where the wind actually came through the gaps on the side of the windows and tore the plastic away from the tape. Thus, the weatherstripping this time
It’ll be a project to put everything up (there are 8 windows in the front sunroom alone), but it will be worth it when it comes to the heating bill!