Resilience Treatments & Strategies
Windows
Description
Openings in a wall that provide light or ventilation, filled with glass (a.k.a. glazing). Windows can have one layer of glass (single-glazed) or multiple layers (e.g. double- and triple-glazed). Individual panes of glass are referred to as lites. Lites are separated by thin strips (muntins, traditionally made of lead and called cames) or larger dividers (mullions). Windows are often character-defining features of historic buildings. Most historic windows were originally operable, although over the years many have been made fixed (inoperable) and no longer allow ventilation. Protective panels or membranes are very important for resilience, shielding lites from debris in high winds. The condition of the frame is also important because it secures the window and in another place where water can infiltrate the building.
Typical risk factor of this component:
High
Windows have very high exposure to elements such as wind and rain. They have little importance to the structure’s stability, although their failure would have some impact on other assemblies.
Typical Damages from Floods or Hurricanes
- Deteriorating window frames (e.g., rotting wood sills, rails, stiles)
- Metal lintels over windows oxidizing
- Cracked window lites
- Failing window sealant or caulking
Other common conditions contributing to vulnerability towards floods or hurricanes
- Lack of hurricane-rated protective panels or membranes
- Sealed condition between window lites and protective panels, allowing moisture to concentrate
- Untempered glazing or plate glass (a safety concern if the window breaks)
- Poor seal or weather tightness
- Inoperable windows
Resilience Treatments and Strategies
In-house
- Install protective polycarbonate (AKA Lexan®) or acrylic (AKA Plexiglas®) panels over windows that are rated to withstand hurricane-force winds. You may need professional help if you have unique windows, such as trace windows.
- Ventilate space between window lites and protective panels so that water doesn’t get trapped there; provide insect screens to prevent infestation.
- Apply safety/security window film to untempered glazing.
- Install weather-stripping to sashes of operable windows.
- Repair damaged pieces of window frame (see also NPS Preservation Briefs #9 and #13). If these need to be outright replaced, talk to an architect first. Some restoration may or may not be doable in-house.
- Recaulk window frames where necessary.
- Replace existing hardware with high-strength hardware. Replacements should be in-kind if possible (may not be feasible if the existing hardware was custom-made).
- Prepare temporary shutters and develop a strategy for securely installing them while minimizing impact on historic building assemblies.
- Restore operability to inoperable windows. Keep in mind that this improves resilience by allow post-disaster ventilation, but can conflict with some types of window protection. You may need professional help if you have unique windows. This cannot be done for some window types (e.g. trace windows).
Professional needed [type]
- Install permanent shutters (only if historically appropriate and designed to avoid impeding egress) [architect].
- Repair, coat, or replace damaged metal components (e.g., steel lintels) with similar assemblies that will resist oxidation [architect].
- Replace cracked window lites or damaged lead dividers with in-kind elements (see also NPS Preservation Brief #33) [architect, building conservator, or window preservation specialist].
- Install protective glazing over individual stained glass lites, which may require rebuilding the window assembly [architect or window preservation specialist].
- Conduct a blower door test to ascertain the building envelope tightness and reveal the leakages within the building [specialist trade].
Windows
Description
Openings in a wall that provide light or ventilation, filled with glass (a.k.a. glazing). Windows can have one layer of glass (single-glazed) or multiple layers (e.g. double- and triple-glazed). Individual panes of glass are referred to as lites. Lites are separated by thin strips (muntins, traditionally made of lead and called cames) or larger dividers (mullions). Windows are often character-defining features of historic buildings. Most historic windows were originally operable, although over the years many have been made fixed (inoperable) and no longer allow ventilation. Protective panels or membranes are very important for resilience, shielding lites from debris in high winds. The condition of the frame is also important because it secures the window and in another place where water can infiltrate the building.
Typical risk factor of this component:
High
Windows have very high exposure to elements such as wind and rain. They have little importance to the structure’s stability, although their failure would have some impact on other assemblies.
Typical Damages from Floods or Hurricanes
- Deteriorating window frames (e.g., rotting wood sills, rails, stiles)
- Metal lintels over windows oxidizing
- Cracked window lites
- Failing window sealant or caulking
Other common conditions contributing to vulnerability towards floods or hurricanes
- Lack of hurricane-rated protective panels or membranes
- Sealed condition between window lites and protective panels, allowing moisture to concentrate
- Untempered glazing or plate glass (a safety concern if the window breaks)
- Poor seal or weather tightness
- Inoperable windows
Resilience Treatments and Strategies
In-house
- Install protective polycarbonate (AKA Lexan®) or acrylic (AKA Plexiglas®) panels over windows that are rated to withstand hurricane-force winds. You may need professional help if you have unique windows, such as trace windows.
- Ventilate space between window lites and protective panels so that water doesn’t get trapped there; provide insect screens to prevent infestation.
- Apply safety/security window film to untempered glazing.
- Install weather-stripping to sashes of operable windows.
- Repair damaged pieces of window frame (see also NPS Preservation Briefs #9 and #13). If these need to be outright replaced, talk to an architect first. Some restoration may or may not be doable in-house.
- Recaulk window frames where necessary.
- Replace existing hardware with high-strength hardware. Replacements should be in-kind if possible (may not be feasible if the existing hardware was custom-made).
- Prepare temporary shutters and develop a strategy for securely installing them while minimizing impact on historic building assemblies.
- Restore operability to inoperable windows. Keep in mind that this improves resilience by allow post-disaster ventilation, but can conflict with some types of window protection. You may need professional help if you have unique windows. This cannot be done for some window types (e.g. trace windows).
Professional needed [type]
- Install permanent shutters (only if historically appropriate and designed to avoid impeding egress) [architect].
- Repair, coat, or replace damaged metal components (e.g., steel lintels) with similar assemblies that will resist oxidation [architect].
- Replace cracked window lites or damaged lead dividers with in-kind elements (see also NPS Preservation Brief #33) [architect, building conservator, or window preservation specialist].
- Install protective glazing over individual stained glass lites, which may require rebuilding the window assembly [architect or window preservation specialist].
- Conduct a blower door test to ascertain the building envelope tightness and reveal the leakages within the building [specialist trade].