If your windows predate about 1950, the wood itself is likely to be valuable and now scarce old-growth wood, which is denser, more rot- and warp-resistant, and holds paint better than modern, plantation-grown wood. Additionally, if a component is damaged it can be repaired or replaced without having to replace the entire window.
While historic windows have all this going for them, they are often the first elements people look to change when trying to improve their home’s energy efficiency. Fortunately, the decision to retain historic wood windows needn’t get in the way of improving the efficiency of your home.
Conserving your historic windows also can be far better for the environment. By repairing and weatherizing your existing windows, you are keeping their valuable material out of landfills and new materials are not required to manufacture new windows.
The repair and weatherization of traditional windows can either be completed by a professional or by the homeowner. If completed by the homeowner, repairs can be done at a much lower cost, since most of the expense of window repair is derived from labor, not materials.
These are recommended publications on how to repair your wood windows:
- Working Windows: A Guide to the Repair and Restoration of Wood Windows (Terry Meany, 3rd ed. Guildford, CT: The Lyons Press, 2008)
- Save America’s Windows (John Leeke)
- National Park Service’s Preservation Brief #9, “The Repair of Historic Wooden Windows”
Be aware that older homes (prior to 1978) may have lead paint. Before digging into repair projects, including window repairs, make sure to learn how to work lead-safe:
- EPA’s “Healthy Indoor Environmental Protocols for Home Energy Upgrades”
- National Trust for Historic Preservation’s Lead Safety page
The simplest ways to gain more energy efficiency from historic windows are to add weather stripping to the sash, make sure that the sash lock holds the meeting rails tightly together, and to caulk the window’s interior and exterior casing to stop air leaks.
Storm windows, which can be affixed to either the exterior or interior of a window, offer additional energy savings. Much like traditionally-constructed cavity walls, snugly fitted storm windows create a void that slows the transfer of heat. In contrast to double-glazing, this technique allows the original windows to remain intact, while providing added insulation and significantly reducing air infiltration.
Adding a storm window to a weather-stripped historic window can achieve essentially the same, and sometimes better, energy performance as a new insulated dual-pane window. Besides providing thermal insulation, storm windows have the added benefit of providing sound insulation as well as protecting the original window from the elements.