Repairing and maintain existing windows maintains value and historic
character, is environmentally responsible and can be much less expensive.
Historic windows can be endlessly repaired whereas replacement windows
have relatively short warranties and once the window fails, the entire sash
must be replaced which creates an endless cycle of purchasing, replacing and
sending materials to the landfill. Manufactures often offer lifetime warrantees
but what they don’t make clear is that 30% of the time, a replacement window
will be replaced within 10 years. Many old windows are made of old growth
wood that is denser and therefore longer lasting than wood available today.
What About Energy Efficiency?
Multiple studies have shown that properly maintained windows with the
addition of storm windows, particularly interior storm windows, can be as
efficient as replacement windows, and also continue to maintain the integrity of
a building’s historic fenestration. While the exact figure will vary depending on
the type of window installed and whether or not a storm window is used,
studies have found that it could take 100 years or more for a replacement window to pay for itself in energy savings. In addition, the majority of energy loss is
through the roof so it may be more cost efficient to replace or increase attic insulation rather than replacing windows.
What Should I Look for When Replacement is Necessary and for New Construction?
• Consider using a “sash pack” that retains both the original window casings, frame and sill, rather than full, costly, replacement of these elements.
• Use simulated divided lights (SDL) with spacer bar or no muntin grills. Bars should range between 5/8” to 1 1/4”, depending on the style of the window.
• Use a mullion, to divide paired or triple windows. Mullion should be 4” to 6” in width as they are creating the appearance of an historic weight pocket.
• Windows used in walls with lap–siding or shingle siding may not use brick mould casings.
• Windows used in walls with brick or stone cladding, should use brick mould casings.
• When a casement–style window is required for a dormer to meet emergency egress requirements, but other similar dormers on the structure have
double–hung windows, a new casement that incorporates an applied grill pattern mimicking double–hung sashes should be selected as these are readily
available from multiple common manufacturers, are more compatible with the building’s existing historic millwork, and fully meet applicable code
requirements for secondary exit of a residential sleeping space.DH windows with 2 tilt sashes also meet emergency egress requirements.
• Storm windows should use blind–stops and have a meeting rail that lines up with the existing meeting rail.