When Gilbert Stanley Underwood designed Jackson Lake Lodge in Jackson Hole, Wyoming, in the early 1950s, he took multiple architectural risks. Not only did he depart somewhat from the Rustic style he had successfully used in previous National Park Service hotels, but he also softened the lodge’s bold, Modernist volumes with an unusual shadowood finish.

Consisting of concrete poured into temporary wood forms so it develops a wood-grain texture and pattern, the finish blended a human-made material with a natural appearance. It helped the lodge, part of Grand Teton National Park, mesh with the jaw-dropping mountain scenery that surrounds it while also telegraphing the building’s modern identity.

Jackson Lake Lodge was completed in 1955; one year later the National Park Service initiated Mission 66, an influential decade of Midcentury Modern design in the park system. “I think [Underwood] accomplished quite a bit by incorporating Midcentury Modernism into a natural setting,” says architect Henry Zimoch, who oversaw an exterior restoration of the lodge completed in late 2022. “Everyone who worked on [the restoration] was excited by the building—we all recognized its value as a precursor to Mission 66.”

Zimoch’s Chicago-based firm, HPZS, spent two weeks on the site in 2019 to begin figuring out how to restore the building’s distinctive surface. The shadowood concrete had held up remarkably well through decades of exposure to the area’s snowy winters, but it was starting to deteriorate. The team would have to develop a way to restore the wood-grain look directly on the building, because the shadowood finish is part of the cast-in-place concrete structure, rather than a separate siding element. In 2000 the original, acid-stained concrete had been painted over, and the team would also have to find a way to remove the paint without causing damage and apply a more historically appropriate coating.

After extensive research and testing, HPZS came up with a plan that satisfied the National Park Service and lodge manager Vail Resorts. Because of Jackson Hole’s harsh winters, the work could only be done in the warmer months: It started in April of 2022 and would have to be completed by early that October. Nelson Engineering, a local firm, would be on hand daily to manage the project.

Crews from Chicago-based Bulley & Andrews Concrete Restoration started by carefully blasting the exterior with pressurized water and fine glass particles to remove the paint. They sandblasted Douglas fir plywood panels to reveal their wood grain and then used the panels to craft forms like the ones Underwood had used to make the original shadowood concrete. Contractors removed damaged sections of concrete; secured the plywood forms to the walls and overhangs in areas that needed repair; and poured concrete into the forms, removing them once the material had set.

About 40 percent of the building’s 75,000-square-foot surface underwent the repairs, says Zimoch. Next, the painstaking process of re-coating the bare concrete began. Replicating the original acid stain wasn’t an option—the existing concrete’s chemical composition had changed over the years, and the acid would no longer properly react with it.

Luckily, a group from the University of Pennsylvania had already worked with Keim, a company that produces specialized paints, stains, and finishes, to research new coatings that would match the look of the stain. Building on their work, the project team identified a combination of products that they layered onto the concrete to protect it from moisture and highlight its wood-grain texture. For consistency’s sake, just two individual painters, working with sponges, hand-applied the final coats of a silicate glaze to the entire building.