Weatherproofing Your Windows
Cut metal or vinyl v-strips to fit in the sash channels.
Cut them long enough to extend at least 1 inch beyond the sash ends when the window is closed. Cut vinyl with scissors; cut metal with tin snips.
Remove the adhesive backing and stick the vinyl in place.
Tack metal strips in place, driving the tacks flush so that the window sash will not snag on them. Flare out the open ends of the metal V-channels with a putty knife to create a tight seal with the sash.
Wipe down the underside of the bottom sash with a damp rag and wait for it to dry;then attach self-adhesive closed-cell vinyl foam to the edges of the underside. The surface must be at least 50 degrees for self-adhesive strips to stick.
Seal the gap where the top sash meets the bottom sash.
For double-hung windows, raise the bottom sash completely to the top, and then lower the upper sash a couple of inches. This reveals the lower rail, which is normally hidden. Seal with V-channel weather stripping. If the top sash is stationary, tack tubular gasket to the outside of the lower sash so that it compresses slightly against the top sash when the window is locked shut.
Apply paintable caulk around both the interior and exterior window trim. Smooth with a wet finger.