Published on: Wed, 02/03/2010 - 16:41
by Robert Roscoe
Windows generally provide trouble-free operation for 40-50 years, requiring occasional painting of outer sash and frame surfaces. Almost all windows have common components: sash that hold the glass, and frame that encases the sash. The sash is made of slender wood strips that surround the glass. The strips can be narrow—just wide enough to slide or swing within the frame, since the glass, despite its thinness, gives sufficient rigidity to the sash.
The frame is also relatively thin, since its stability is provided by attachment to the building’s structure. The traditional window frame secures the sash in place with narrow ribs, called stops, within which the sash slides, and crafted with precision so that just enough clearance is provided for operation, yet tight enough to resist weather penetration. Double-hung window units have two sashes, upper and lower, that slide up and down in separate tracks, divided by stops.
Many owners of older houses with worn and troublesome windows seem to think it reasonable to replace the existing sash with new units that would be tighter, easier to operate, and have Thermopane, or more energy-efficient double glazing. However, in most situations, even window frames that are over 100 years old are typically still solid. The frames can be retained, though occasionally sills—the slightly sloped wood member at the bottom of the unit—need repair. In order to fit original frame openings, custom sizes can be made by most window manufacturers, and the upcharge over “stock” readily-available units is not sizable.
More and more homeowners today are choosing to repair window sash rather than replacing them. Their reasons are the extra measure of authenticity, and often the cost of repair is less than replacement, especially if the original windows have multi-paned sash. Sometimes there is the visual intrigue of the wavy glass that century-old windows sometimes offer.
In St. Paul there are many window repair specialists today who can completely rebuild existing windows. This reconditioning can include weather-stripping that can make the total window unit as weather- and infiltration-tight as new units. In many cases, the deficient part of older window sash is the bottom rail that rests on the sill, affected over time by wet conditions. Those loose or deteriorated bottom sash rails can be made tight again or replaced if necessary. Although original windows are single-glazed compared to the double-glazing typical of new sash, equivalent efficiency can be gained by installing storm windows, another traditional component returning to use today.
