creeser Lowe's and Home Depot sell shims, which are thin wood wedges carpenters use in building things. Try wedging some of those gently in between the window and the wood.

Betty Flippin Meyer Thank you!!! I will look into those today!

creeser Hope they help. At least they'll be cheap to try. They probably aren't but like a dime a piece.

Ironwood Builders From your description, it sounds like a double hung sash, one where the bottom window lifts and has ropes that keep it in place? With type of window, a certain amount of 'wiggle' room is necessary to keep them sliding...I've restored hundreds to working order that had been painted shut. But making them tight is a challenge. We've installed traditional storm windows over historic double hung sash for weather issues (cold in Indiana in the winter). That may be one solution, though most of the aluminum storm window fabricators have gone out of that business and shifted over to replacement window installs. There are interior storm panels available they tend to use a magnetic strip for keeping the window in place and Lexan or polycarbonate for the clear panel. I've not used them. One cheap alternative may be to pack foam strips into the gap and not open the window. None of these suggestions address security... The best security measure for a double hung is to drill a 3/16" hole at the interior of the parting strip (where the windows overlap) and insert a cut off 16 penny nail. Enough to slow someone down...all windows are subject to break and enter crimes.

Betty Flippin Meyer Thank you! That is an issue also. There are no storm windows on the outside of house so trying to control air leakage has been a challenge too. Plastic helps but doesn't control it all. Very OLD windows and yes they have the rope pulley sytem. Thank goodness I will be moving in a couple months. A year here has been a very valuable experience! Thanks for your help!

Linda Some of the more expensive double hung windows have adjustable window stops. Instead of being nailed on, the stops are held in place with screws through a slotted washer inserted in the stop. So, in the spring, you would loosen the screw and pull the stop away from the window and in the fall you would reverse that to tighten up the stop and keep the window from rattling. Adjusting those was part of the ritual of swapping the storms for the screens.

For a temporary fix try taping over the opening where the pully for the lower window comes through the side of the window. Buy some cheap caulk, either clear or white depending on the window, and calk every gap you see. Also, check to see that the windows are actually closed; sometimes they get racked and don't actually go up and down all the way. You may need to take a rubber mallet or a board with a hammer and give them a good whack to get them to shut completely.