A few miles outside Boulder, Colorado, in the tiny town of Nederland, it’s still common to hear bluegrass wafting down streets that have changed little since their settlement in the silver-mining era. It’s a place where building a house can be an all-hands community effort, using materials supplied by the surrounding land, and the imperfections of a human touch are a value-added proposition.

Rob Pyatt and Heather Kahn met while working on such a project in 2000. Kahn, an artist, hired Pyatt, a builder with an art degree, when she was managing the construction of a straw-bale house in Nederland. The home was designed using traditional straw-building techniques: stacking thick bales into walls, then coating them in stucco. The result was smooth and earthy, with soft corners and hand-molded window frames. “It turned out well,” says Kahn, “all things considered. You have to go into it knowing that it’s a different type of work.”

Over the course of the project, Pyatt and Kahn began dating, and the job culminated with their engagement, which Pyatt proclaims was the best thing to emerge from the endeavor. They combined two households into Kahn’s 900-square-foot bungalow in Boulder and were married in 2002. Soon after, Pyatt entered the University of Colorado, completing an undergraduate degree in environmental design, followed by a master’s in architecture.

Compact living suited the couple—until the prospect of starting a family began to make things look smaller. With a limited budget and Boulder housing prices booming, a self-designed addition seemed like the only realistic option. But a repeat performance of the folksy Nederland project was not in the cards. Though just 15 miles away, it’s a cultural leap from sleepy “Ned” to the lively neighborhoods of Boulder, where an infusion of tech start-up chic gives the town a semi-urban flavor.

The house would be decidedly modern, they agreed. But they weren’t starting from scratch. Their tiny 1940s cottage hadn’t seen significant updates in its six decades, and the home’s age, combined with the duo’s strong commitment to executing the project sustainably, meant preserving as much of the existing structure as possible. “The foundation is such that we really couldn’t go up without doing work down there, so we just adapted what we had,” Pyatt explains.

On their larger-than-average lot, they had ample space to construct a sizable wing, but they chose instead to preserve the backyard and build a compact addition that would take full advantage of indoor/outdoor living in a region renowned for its nearly year-round sun. Inspired by traditional Southwestern courtyard houses, Pyatt designed a simple box that would attach to the original entryway, creating a partially enclosed concrete patio and outdoor dining area at the rear of the house.

With their first child on the way, the clock was ticking, but Pyatt isn’t one to cut corners. As he neared the end of architecture school, instead of trying to juggle his home-building project with coursework, he wised up and turned the former into the latter. Encouraged by his advisor, Rick Sommerfeld, Pyatt created an independent study that would earn him school credit for designing and building his family’s home. This afforded him the flexibility to research and experiment with materials and systems in order to push the envelope on sustainability.

Construction began in 2005, just after Pyatt finished advising a team of designers from the University of Colorado on its submission to the Solar Decathlon, the U.S. Department of Energy’s biennial architecture contest held on the National Mall in Washington, DC. The team took first place, winning with a design that focused on modularity and natural materials, a perfect prelude to Pyatt’s own project in progress. The small Decathlon house was made with specialized bio-based lightweight structural insulated panels (BIO-SIPS), invented by one of the team’s supervising professors, architect Julee Herdt. Working with the prefab panels was an inspiring shift from Pyatt’s early straw-bale projects toward more industrial uses of recycled agricultural by-products. He and the team further embraced the potential of farm waste by carting their creation to and from DC on trucks fueled by biodiesel.

Back in Boulder, Pyatt merged his love of straw construction with his interest in prefab systems by going to the compressed straw–panel manufacturer Agriboard Industries. “They didn’t have a thick enough panel for Colorado, so I worked with the engineers to make a prototype,” he recounts. “It’s 12 inches thick, with a higher R-value (resistance
to heat)—more similar to straw bale. Our working model is an R-38, whereas the more popular six-inch is much lower.” The efficiency of the envelope was then reinforced with recycled-cotton insulation from Bonded Logic Inc., a company known for its innovative reappropriation of discarded denim. Pyatt replaced the windows throughout the house with superinsulated panes from Alpen Energy Group, a company that produces a low-emissivity coated glass called Heat Mirror, which reflects heat back toward its source—away from the house in warm weather and into the heated interior during winter months. Alpen Energy’s glazings are customized according to the orientation of each window, notes Pyatt, “so if you have a south-facing wall, you’d want passive solar glass that lets in radiation, while western-facing glass blocks the radiation.”

The more immediate needs of the couple’s kids played a big part in considering indoor air quality. They chose low- or no-formaldehyde plywood, nontoxic adhesives, and zero-VOC paint, and staunchly avoided materials that are known to off-gas or contain toxic compounds, including carpeting on which the kids would inevitably roll around and kick up particulates. “In every instance where we had to make a decision on a product,” says Pyatt, “we would evaluate that product and look at alternatives and figure out how it would work from a conventional construction standpoint and how it would look for a new way of construction with prefab.”

On a street dominated by conventional residences, the family’s deviations from the norm attracted attention, not all of it supportive. The corrugated-metal cladding that covers a portion of the exterior stands out against the warmer wood-plank facade and in the beginning stirred some rumblings among the neighbors. “Nobody raised hell, but through the grapevine we heard that people were saying, ‘What on earth are they doing?’” Kahn recalls. “But over time it seems like the reaction is really good. And as soon as somebody walks in, they’re just in love.”

Nearly doubled in area, the 1,700-square-foot home still uses space efficiently and conservatively, accommodating Pyatt’s office and Kahn’s studio, in addition to three bedrooms and two bathrooms. There’s even room for Pyatt’s brother, Kirk, who helped build the house and moved in afterwards. “This little house feels big and open,” Kahn muses. “I wanted to be able to be in the kitchen and hear what my kids were doing, or see them outside, and just have it feel very functional and natural and cozy.”

As their two young sons get bigger, there will surely be times when cozy verges on crowded, but with luck (and a yard big enough to burn off excess energy), the boys will take as much pleasure growing up in this house as their father did in building it. “It was definitely a labor of love, and as an artist turned builder the creative aspect of design-build was a joy,” says Pyatt. “Some of my best memories will be of having a beer with my brother after a successful day building the house together.”