When Tammy Heesakker and Gregory Russo's real estate agent first brought them to see a modest, low-slung house on a hill in Norwich in 2015, the renter was practically camping in the living room and the place was falling apart.

"It was in a mad state of disrepair," Russo recalled. Nevertheless, he recognized the look of the 1961 house: poured-concrete floors, built-ins, narrow hallways that opened to a lofty living space with high clerestory windows. It looked like a house designed by celebrated 20th-century architect Frank Lloyd Wright.

"I was a fanboy," Russo explained. Now a radiation oncologist at Dartmouth-Hitchcock Medical Center, he grew up with a poster of Wright's Fallingwater in his bedroom. Years later, he and Heesakker visited that iconic western Pennsylvania residence while living in Philadelphia.

The couple were living in Boston when they saw the Norwich house. Suspecting that the real estate agent had misidentified its architect — she had named someone they'd never heard of — they searched online and discovered it was designed by Allan J. Gelbin. A Wright acolyte, Gelbin apprenticed at Wright's home studio at Taliesin East in Wisconsin from 1949 to 1953; he subsequently oversaw the construction of several Wright-designed homes and opened his own practice in Connecticut in 1957. (Wright died in 1959; Gelbin, in 1994.)

An address cross-check with the Gelbin archives at the Art Institute of Chicago confirmed that Gelbin designed the 2,100-square-foot, three-bedroom Norwich house for Walter and Sylvia Stockmayer and their two teenage sons. The Stockmayers had engaged Gelbin on the recommendation of their friend Lucille Zimmerman, whose 1951 Wright-designed house in Manchester, N.H., they admired.

Faced with such historical importance, Heesakker and Russo decided to take on the Stockmayer home's rehabilitation. White River Junction architect Daniel Johnson guided the multiyear project, and Heesakker, who works in technology licensing at Dartmouth College and was then running her own consulting business, became the general contractor. She and Russo flew to Chicago to study the Gelbin archive's correspondence, plans and documents in person before launching their project.

Their efforts won a 2022 Modernism in America Award of Excellence from Docomomo US, a nonprofit dedicated to the documentation and conservation of the modern movement. The house is now listed in the national and Vermont registers of historic places.

In early June, the house was filmed for inclusion in the forthcoming 2023 documentary New England Modernism: Revolutionary Architecture in the 20th Century by filmmaker Jake Gorst. His films have examined the midcentury architecture of Long Island and Southern California, as well as period architects such as Albert Frey and Andrew Geller.

Vermont state architectural historian Devin Colman, who wrote the award nomination, noted in it that the Stockmayer house is "architecturally significant as a very rare and well-preserved example of Usonian design in Vermont." Usonian houses were Wright's compact and affordable version of his Prairie style and the progenitor of ranch-style houses in the U.S. The name comes from the acronym for United States of North America.

The nomination continued, "It easily could have been considered a tear-down, given its poor condition, small size, and valuable property, but fortunately the current owners ... saw its potential."

Heesakker and Johnson, principal and founder of Watershed Studio Architecture, recently gave Nest a tour of the house. Approached from the side via a carport, the long, low structure is built into the hill with the rear length sunk into a four-foot bank and the south-facing front side overlooking a stunning view of the Connecticut River Valley. On leafless days, Mount Ascutney is visible.

Rescue efforts started with the unique roof, which is flat with an asymmetrical central gabled portion — that is, one angle of the gable is longer and lower than the other. The couple replaced the asphalt-and-pebbles construction with a rubber membrane edged with metal.

Inside, the "compression and expansion" typical of Usonian houses, Heesakker noted, is expressed in the way the narrow hallway paths lead from the front door to the open-plan dining and living areas and an office beyond a partial wall. Wright's organic architecture favored natural materials, so the walls are made of dark golden-hued cypress wood in wide boards punctuated with narrow battens, all horizontally oriented to emphasize the shape of the house.

Other walls in the living area are made of red brick manufactured in a nearby Vermont town, according to Gelbin's papers. He designed the decorative arrangement of cypress boards spanning the space between the top of the kitchen wall and the peaked ceiling — an eye-catching construction that Heesakker described as sculpture.

A light sand-colored, pebbly plaster completes the indoor wall materials — except for glass, which is everywhere: a wall of plate-glass panels stretching across the front façade; windowed gable ends; an office corner, where two windows meet à la Fallingwater. More light filters through two skylights.

Asked whether it was accurate to call the house Wrightian when Gelbin was the architect, Johnson opined, "You wouldn't recognize how Gelbin's style is different from Frank Lloyd Wright's. Even Wright's designs weren't entirely done by him; his apprentices did them."

Johnson's own work is influenced by the organic architects, particularly Finnish midcentury master Alvar Aalto; his interest in "light, landscape and materials," he said, echoes theirs.

In the Stockmayer house, Gelbin's original elements, restored by Heesakker and Russo, are all around, including the built-in cypress couch with new, custom-made cushions; the hanging Wrightian wood dining lamp and wall sconces with new fiberglass-paper shades; the original red Micarta kitchen countertops; and cypress cabinet boxes with new cypress doors stained to an exact match.

The couple's biggest intervention is invisible. The house's main source of heat, aside from a substantial brick fireplace, is radiant copper piping buried in a terra-cotta-colored concrete floor that's scored in a four-foot-square grid. The heated floors had failed in the primary bedroom and bath, so Johnson supervised the floors' dismantling and the installation of new pipes that travel from the central boiler room over the top of the kitchen and down through the walls.

"It was either that or having to dig a hole underneath the house to run them through," Russo said, noting the house's slab construction. New interior floors were poured using Wright's favored technique — applied color hardener rather than integral color with as close a match as possible.

"They were very rigorous and passionate about the house," Johnson said of his clients, adding that only one part of the project, the primary bath, went beyond restoration to renovation. Describing the bathroom as dark and outfitted with a tub that wasn't original, the architect came up with the idea of expanding the floor plan to include an attached, Gelbin-designed brick planter outside the bathroom window. The house's footprint thus remained unchanged while enough interior space was gained to install a shower.

Now that it's summer, the Stockmayer house owners can enjoy its most Wrightian feature: the way outside and in meld through the continuation of the concrete floors to a wide outdoor patio edged with gravel. (Heesakker and Russo actually spent a summer with a wheelbarrow and sieve, rescuing the original gravel from the weeds rather than having it dug out and replaced.) Heesakker's gardens expand down the hill, and Russo's poured-concrete benches — a pandemic hobby — dot the yard.

"The house gets twice as big in the summer," Russo declared.

The Stockmayers provided the impetus for Gelbin to come to Vermont; he subsequently designed and built four more homes in the Green Mountains between 1961 and 1975 — including his own, a short drive down the hill from the Stockmayers'. That one, the Allan Gelbin House (1973), is on the Norwich Historical Society's popular midcentury walking tour.

The twice-a-summer offering (exteriors only) began in 2017, when director Sarah Rooker researched and mounted a Norwich midcentury modern architecture exhibition at the society. (The Stockmayer House is not on the tour because it's not within walking distance.)

Colman recalled seeing the Stockmayer house shortly after Heesakker and Russo had completed their project. "After restoring the underslab hot-water heating system — like, who does that? — and seeing everything they'd done, I thought, Amazing," he recalled.

"I didn't get the sense they were necessarily looking for an iconic house to restore," Colman continued, "but I think they're the type of people who take the time to understand and learn about things, and once they realized they had something special, they were able to switch their thinking from Here's a rundown house that we're going to renovate to Here's an important work of architecture that we need to restore.

"They're the accidental preservationists," he added.