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Options for replacing divided lite historic windows?

11/15/2023

One of the most challenging aspects of window rehabilitation projects is the use of true divided lites, as this method poses several difficulties that can compromise the thermal integrity and structural efficiency of the frames.

These difficulties include issues with temperature transfer, higher glass costs, increased glazing and labor costs, poor load deflection, and reduced structural integrity. Furthermore, the traditional process does not allow for the standard 1/8 inch spacing between the glass edge and spacing bar, which can lead to inconsistent sightlines, exposed spacers, UV light damage, and seal failure.

SCW3000 Series / simulated divided lite fixed windows / Springfield Technical Community College Student Learning Common

To overcome these challenges, it is recommended that a simulated divided lite system be used for historic window replacements. This approach uses applied grids to replicate the historic design of the original windows, maintaining the historic integrity of the building. The dimensions of the simulated divided lite system can be adjusted to match the exact requirements of the building, achieving sightlines of 7/8 inch or narrower.

Unlike the true divided lites method, the spacer is not exposed in the simulated divided lite system, reducing potential whistles or rattles. Most importantly, the frame is thermally broken, the insulating glass is not compromised, and the limited glass perimeter reduces air and water infiltration, making this system much more energy efficient. 

The critical features of a historic window replication include:

  • Accurate sightlines
  • Custom-matched profiles
  • Ability to replicate existing elements (i.e. projecting vents)
  • Duplication or original muntin grid design
  • Energy efficiency
  • Performance and sustainability

An example of a successful historic window replacement project is the transformation of the 170-year-old historic Springfield Armory into Springfield Technical Community College’s new Student Learning Common. Today, the building is an accessible, sustainable, and vibrant part of campus life, housing administrative offices, a student commons, student services, a health center, a café, study spaces, a library, and a campus bookstore, featuring over 550 fixed frame SCW3000 Series windows, demonstrating the effectiveness and viability of simulated divided lite systems in historic window replacements.

If you’re considering reusing a building, contact us for a quote and learn more about St. Cloud Window’s historic aluminum doors and windows.

At St. Cloud Window we know every project begins with a challenge or an idea of what a building might be. We bring that vision to life with our distinctive design aesthetics, precision performance, and design-to-delivery support. Learn more about how our products can deliver on your design objectives and site requirements here. Then, check out our full line of historic replica and acoustic window products, and get in touch for more details about any of our high-performing commercial window products.