Matching Window Details with Precise Historic Casing

When it comes to historic architecture, true-to-era window exteriors are of paramount importance. Now it’s possible to replicate these historic details down to the millimeter.

January 17, 2022

Whether designing new buildings that honor a specific historic aesthetic or rehabilitating century-old structures by replacing windows, architects specializing in historic styles know that it’s all about details, details, details. And those details all reside in the intricate exteriors of true-to-era buildings and homes.

“Being as close as a 32nd of an inch away is important,” said Jim Pelowski, an architectural expert at Marvin. “The closer you can come to hitting those critical dimensions, and not reducing the daylight opening, the better. Sometimes you will drive by a building or a residence, and you can tell they replaced the windows because the daylight opening looks a lot smaller.”

To maximize these daylight openings, windows in historic projects benefit from clad exteriors that meet strict guidelines from the National Park Service. They do this by matching original window sightlines (the amount of window frame that you see when looking directly at the window). Marvin’s historic solutions team continues to push the limits of what is possible in historic accuracy and developed an historic casing that virtually replicates original historic window casing details. Pelowski describes window casing as a sort of “cap” for the jamb of double-hung windows, single-hung windows, and round-top windows.

“We have this unique option that provides us with much closer detail to what’s in most existing wood window applications,” Pelowski said.

This means that double-hung, single-hung, and round-top windows can be clad with the most historically precise exterior to-date.

Achieving Historic Precision 

Double-hung windows from the 1920s, which are prevalent in historic architecture across the U.S., drove the development of this newest historic casing solution, which is virtually identical in casing widths.

“The historic significance of the building dictates how close you must get to the original,” said Bill Boyd, Senior Product Manager at Marvin. “This historic casing solution takes the detail to another level. With historic windows it’s about proportions. We developed a solution to address each pain point, where there is loss of daylight opening due to sightlines, and we’ve lined up close. The farthest we are off is 3/32 of an inch.”

The visual below reveals the closeness of the new historic casing overlayed with a 1920s original window. The black lines represent the Ultimate Double Hung G2 window with historic casing, and the red lines show the outline of an original 1920s double-hung wood window.

“What's really nice and about this is that it caps the window perfectly, so you get the sightlines, which is very important to historic projects,” Boyd said. “If you’re a historic architect, your first objective is to rehabilitate that window. But if it cannot be rehabilitated, it must be replicated. The building owner also wants a window that has better performance, thermally and structurally. That’s where this historic casing can deliver.”

Durable Materials that Replicate Original Details

Replicating historic details in the overall appearance of the window casing is important for historic projects, but so is the material and performance of the window. After all, if a building is undergoing rehabilitation, the goal is to restore it and keep it pristine for as long as possible.

The historic casing for the Ultimate Double Hung G2 window is made of extruded aluminum, which is about the thickness of a quarter. Aluminum that’s extruded allows for more detail and is far more durable than roll-form aluminum. In fact, it can be used in different climates and regions throughout the country.

“Our performance levels don't change from our base units, so you can use this on commercially rated windows performance,” Boyd said. “This is a great solution for coastal environments with historic roots, like Savannah, GA. You can use this historic casing and replicate the look you’re going for.”

Built to withstand weather and the test of time, the casing is factory-installed in double-hung, single-hung, or round-top windows and is ready for on-site installation for a range of historic projects.

“What’s really interesting about this solution is that we've been able to make aluminum look like wood,” Pelowski said. “It really resembles what an existing wood window that's 100 years old would look like. We can recreate that appearance in aluminum-clad, with a wood interior."

Unlimited Customization for Any Project

Historic projects run the gamut in terms of styles and the details therein. That’s why exterior clad options cannot be one-size-fits-all. The historic casing comes in 19 colors, plus custom colors, and is available in four common shapes with the option to create custom shapes, as well.

The image below shows four common shapes used in historic window casings: two-inch flat casing, Ridgeland casing, two-inch BMC casing, and Thornton casing.

When it comes to mulling (when two windows are joined together), there are no restrictions on what is possible. So, for architects specializing in historic projects, the smallest of details is possible to create, or recreate.

Historic styles in new projects and restoration projects produce buildings and homes that tell a story. Now, with clad options that more closely than ever resemble original wood character with precise exterior details, the future of historic projects is infinite, and can tell countless stories with historic accuracy. Find an expert to discuss these historic solutions.

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