Storm Windows: Comfort Without Replacing Old Windows

The most practical thing you can do for an old window is often to leave it alone and hang storm windows in front of it. Storm windows are unglamorous. They're also why a hundred-year-old sash can keep working through winters it was never built to handle.

Still air does the work

The logic is old and simple. An original wood window is one layer of glass in a frame that's already proven it can last a century. Its weakness isn't the glass. It's the thin, leaky air the assembly lets slip past. A storm window adds a second pane and, more to the point, a trapped layer of still air between the two. Still air is the insulator. That dead space does most of the work: it blunts drafts and slows the heat loss and the condensation that rots a sash from the inside.

Replacement gets sold as the modern answer, and for a builder-grade window it might be. For an original one, replacement throws out wavy old glass, wood milled from denser timber than you can easily buy today, and joinery designed to be repaired instead of discarded. A storm window keeps every bit of that and solves the cold problem beside it. The parts that make it work are small enough to overlook: the hangers that let an exterior storm sash mount and lift, the turn buttons that hold it, the clips and fasteners that let the whole thing come down in spring and go back up in fall. When one goes missing, a window stops being seasonal and starts being stuck.