Design Considerations for Pre-1940s Steel Window Rehabilitation

Steel windows are a character-defining feature of many older buildings. Single-pane, rolled steel sash windows were common in pre-1940s warehouses, commercial offices, and historic institutional buildings. But with steel comes corrosion: most older window rehabilitation project teams must contend with treatments for removing rust in-situ or off-site, options for new paint systems, and methods for reglazing, and they must consider whether the ventilator sash should be made operable again. Thermal performance and occupant comfort issues may impact the decision to repair original steel windows or replace them with new higher-performance windows.

In this recorded Building Science Live webinar, Sarah Gray and Megan Cross-Wilkinson discuss components of steel windows, materials, and details for steel window repainting and reglazing, and considerations for replica windows. They highlight three case studies that address different treatment options depending on historical significance, climate, occupancy, and project budgets.

This webinar will be of interest to architects, building owners and managers, and contractors and developers who work with existing and historic buildings, particularly buildings that are mid-rise and high-rise and that were built before the 1940s.

You’ll Learn About:

1. Common terms used for historic windows.

2. Building science principles and related issues for historic windows, including airtightness, water shedding, and thermal performance.

3. Options for rehabilitation and renewal of existing windows, including operable components, with consideration for occupant comfort and thermal performance.

4. The mock-up process to verify successful retrofit of frame joinery, reglazing seals, and repairs to operable vents.

5. How preservation and performance are balanced in three case studies:

a. Full rehabilitation of 80-year-old steel windows in a historic warehouse previously used for shipbuilding. The window rehabilitation includes removal, recoating, and reglazing in a controlled factory setting.

b. Rehabilitation of existing windows and the addition of a new interior sash to improve thermal comfort and airtightness.

c. Replacement of old windows with new replica windows.