By Cindy Boehlke and Steve Hochstadt / HPC
Hardly anyone thinks replacement windows look better than original windows on historic homes. But when homeowners look at old wood windows, they often think that they need to be replaced for energy efficiency. Contrary to popular belief, little energy efficiency is realized from modern double-pane or triple-pane windows, compared to original wood windows with simple storm systems. Even when real wood frames are chosen, the quality of wood is inferior. America’s older buildings were built from lumber from the ancient forests, where trees grew slowly and straight. With up to 30 growth rings per inch, this clear and dense wood is superior in stability and decay resistance to today’s commercially available lumber. Lumber companies now plant and harvest genetically altered trees, which reach maturity in 15 years or less. With only 3 to 5 growth rings per inch, this material is less stable and more prone to decay. Plantation-grown material is less effective in holding paint, as it expands and contracts at a much higher rate. These new glass units have an expected life of 25 years or less, unlike your windows which might already be 100 years old. Too often, ancient high-performance lumber gets replaced with inferior plantation-grown material. The cost of new windows is rarely justified. Brandon Thiele, the founder of Chicago Energy Consultants says, “The money that you would typically spend on that is typically better spent on sealing air leaks and increasing insulation levels.” We recommend refurbishing original wood windows. Use weather stripping, replace missing glazing, check that weights work on sash windows and wax the channels in which sashes slide if they stick. If there is damaged wood, restore it. Most people are surprised to find that just below the surface of a seemingly unsalvageable piece of wood is quality wood, sound and bright as the day the house was built. Inspecting with an awl or a penknife will allow one to “see” beneath the wood surface. In many cases, the decayed or damaged wood is only near the surface. Your old house will appreciate the attention.