How can I raise double hung windows in an older home that are stuck shut?
If your window has been painted shut, start by unlocking it, then carefully cut through the paint layer where the window stop meets the sash using the corner of a putty knife or a utility knife. Bump the top frame of the sash with your hand or a rubber mallet to loosen it, then try raising the window.
If that doesn’t do it, go outside and insert a flat pry bar between the sill and sash on one side of the frame. Pry upward a little to loosen it, then repeat on the other side of the frame, working each side until it raises. Once you have it open, spray a little lubricant or rub paraffin in the track on each side of the frame.
If the windows are still difficult to open and close, you may need to remove the window stop in the room and slightly increase the gap between the window stop and sash, or take out the sash and plane off the side edges until it slides easily.
Good luck with your project,