Windows in Indiana take a real freeze, a humid summer, and wind-driven rain. Older wood swells, sticks, then opens at the joints when it dries. Newer vinyl fogs when the seal dies and stays cloudy. A cold room next to working heat is often the sash, not the furnace. A rattling storm panel is not a plan.
An insert leaves the old frame in place, which is fine on a solid sill and a mistake on a soft one. Full-frame work opens the rough studs when the wood is mush. Some painted-shut sashes can be freed and rebalanced if the glass is still clear. Say what the sill feels like. Keep old paint dust contained if the trim is chalking.
Summer humidity shows failed seals that winter only made drafty. West and south faces take more sun and more storm wind. A window over a porch roof stays wet longer and rots the stool first. Ask how the sill is flashed and what fills the gap around the frame. Interior trim and an outside cap are part of finishing, not a favor.
Count the rooms that fail rather than every opening on the house. Subdivision vinyl often shares one age, so one fogged bath may mean more, yet report only what you see. An older main-street house may have a rotten bath window and sound front sashes. Say the town, the floor, and whether the problem is rot, fog, or a draft you can feel with the heat on.
Do not sand chalking paint through the room, and do not treat a label on the glass as the whole story of the wall. Wind-driven rain on the west wall is the opening to name first. Subdivision fog and old-town rot should not be mashed into one story. Say how many openings hurt. Call the number on this page.