Don't replace; restore!
Double-hung windows have two sashes that slide up and down past one another. Frequently, we will find a home in which the upper sash in every window has been painted shut. This has led many to believe that they have single-hung windows, however in the last ten years we have never encountered an antique single-hung window of this configuration in San Francisco.
Double-hung windows with traditional weight and pulley systems are the most durable and most serviceable type of window. These windows come apart to replace sash-cords (ropes). The double-hung design, created to facilitate easy cleaning of the outside of the glass, also allows for free air flow while promoting child safety. When both the upper and lower sashes open and close freely, a person can not only open the upper window for venting the kitchen or bath, but it is now possible to easily wash both sashes from within the building simply by sliding the two panes to different positions.
How we reapair old drafty windows that rattle varies from one house to the next and, frequently from window to window. In general, Victorian buildings here have settled, often significantly. While we have a window apart we use a hand plane to create an optimal fit along the top and bottom edges of sashes to create a tight fit and to reduce drafts. To further reduce drafts as well as street noise, we install a traditional bronze weatherstrip. As we reassemble each window, we work carefully to fit things together tightly as best possible while allowing windows to open and close smoothly.
An upper sash. This is how to repair the decayed wood in this rotted Victorian window sash; by replacing the meeting rail entirely.
Diagram of the parts of a traditional double-hung Victorian window.
This is the best way to repair a drafty arched antique Victorian window; by adding wood to the top of the sash.
A fully restored drafty antique Victorian window with traditional bronze weatherstrip.