Sometimes, window replacement is the only option that makes sense. Below are some of the conditions for which replacement of old windows with new may be warranted.
• Rotten or broken frames. Windows are supposed to resist wind and wind-driven rain. If the wooden window sash or frames are degraded to the extent that they can’t serve this function, they must be replaced. In some cases, efforts to protect windows have done just the opposite—some paints trap moisture in wood windows and cause decay. Inadequate roof overhangs often allow repeated wetting of windows that also leads to decay.
• Seal failure. With insulated, multipane windows, seal failure is revealed by moisture between the panes. If only one insulating glass unit (IGU) has failed, just that IGU could be replaced, but with multiple failures it may make more sense to replace the sashes or windows.
• Inadequate functionality. Most of us want windows to be operable so that we can let in the cooling summer breezes. Windows that won’t open because the tracks are worn out or casement mechanisms are broken may be candidates for replacement if their components can’t be fixed.
• Substandard energy performance. In exceptional cases, the energy performance of windows may be so poor—through air leakage or heat conduction—that replacement is the only wise solution. Jalousie (louvre) windows, for example, are leaky by virtue of their design. Steel- and aluminum-framed windows without thermal breaks in their frames are notorious energy wasters due to their conductivity. And some windows may not accept weather-stripping to reduce air leakage. If you’re unsure about your window’s energy performance, consider hiring an energy auditor or building contractor to evaluate the windows.
• Lead paint. Many pre-1970 windows are coated with lead paint. When that paint can’t be safely stripped or sealed, they may require replacement. The biggest concern for exposure is when the paint is subject to abrasion from sliding action.
When wooden window frames have degraded to this degree, it’s time to consider replacement.