Architect Brian Fuentes designed Boulder’s first pop-top with a straw-bale wall for JP and Julie Boylan. The home’s entire north wall is made of straw. Photo by Erik Paulsrud Photography

This earth-plastered Golden home features wood-frame construction with straw-bale in-fill, which is often easier to permit than a load-bearing straw-bale structure. Photo by Johnathan Heneka, courtesy Fuentes Design

Straw-bale construction perfectly complements the shapes of Southwestern adobe-style architecture. Photo by Pam Moser

Straw-bale walls can prove challenging in kitchens with built-in cabinets. To span gaps between the cabinets and the wavy straw-bale walls, JP and Julie Boylan created a backsplash with a Moroccan-style waterproof hand-plaster technique called Tadlakt. Photo by Erik Paulsrud Photography

Deep, reflective window wells are a nice perk of straw-bale walls. They also allow space for growing plants. Photo by Erik Paulsrud Photography

straw-struck

Straw-bale houses are not only energy efficient and a greener solution, they’re fun to construct, with good old-fashioned work parties coming together to raise the bale.

By Tyera Eulberg

Children anywhere can tell you: Never build a house from straw. It’s flimsy, thin, and for those who opt for such a quick, simple solution, a gruesome end (in the belly of the Big Bad Wolf) surely awaits. But after you glimpse the straw-bale houses popping up locally—like the sprawling hacienda in Longmont or the off-the-grid two-story in downtown Boulder—you too will likely clamor, “Little Pig, Little Pig, let me in!”

Like jazz music and baseball, straw-bale construction is an all-American invention, originating in Nebraska’s Sand Hills. Settlers there found little lumber or suitable sod for house walls. When the horse-driven baling machine rolled into the region in the 1870s, it turned loose straw into solid building blocks. The settlers stacked the bales and coated them with mud or plaster to make sturdy, weatherproof walls. (That first Little Pig just needed a baler.) As soon as railroads came through, Nebraskans began building “real” homes with the steady supply of brick and timber, and the straw-bale tradition faded away. In the 1970s, home builders interested in sustainable techniques rediscovered straw bales. Popularity has grown ever since, and as it turns out, straw—a much-maligned building product—may be the greenest, sturdiest wall material available today.

Tony Delcavo stumbled across a straw-bale building book a decade ago. A self-proclaimed “tree-hugger,” Delcavo liked the idea of building with a waste product; from their Douglas County property, he and his wife, Pam Moser, could see the smoke of farmers burning off straw in late autumn every year. Delcavo also wanted off the grid, and straw’s insulating power fit perfectly into his plan. Straw rates at R-45 to R-50, compared to R-15 for typical drywall with fiberglass or cellulose sheets. So the bales, with lots of so-called thermal mass, would retain Delcavo’s passive solar heating more than twice as well.

The couple’s 9-year-old straw-insulated house has exceeded their expectations. “It’s comfortable and the temperature is very stable,” Delcavo says. On hot days, they close up the house and, because the straw absorbs cool air at night, it feels like air conditioning. Plus, a pleasant side effect is the near-silence inside the house, as straw insulates from noise as well. “The quiet is an amazing thing we didn’t think about,” Delcavo says.

Old-Time House Raising

For Moser and Delcavo, the next best thing to living in their straw-bale house was building it. One weekend in late fall, about 30 friends and family came over to help stack bales. By 1 p.m. on Sunday, the walls were done. “It was great fun,” Moser says. “There was kind of a competition about who could get the straightest wall.” Those that aren’t so straight are still sturdy, and offer proof of everyone who chipped in.

Because straw walls are just bales upon bales stacked like bricks, their simplicity means anyone can build this type of house, with a little professional guidance. Indeed, community work parties erect the vast majority of straw-bale walls. In addition to personal acquaintances, people can find willing workers through the Colorado Straw Bale Association (COSBA) based in Boulder. COSBA advertises projects on its website and helpers usually show up in droves. “A lot of people work at desks, and straw bales offer you the opportunity to stand back and look at what you’ve built in one day,” says Mark Schueneman, COSBA executive director. “It’s contagious.” The association also offers straw-bale resources (everything from architects to farmers with bales to sell) and teaches straw-building workshops worldwide.

Builder Garrett Mundelein hosted four weekends of workshops when he put up his two-story straw-bale home in Louisville. Attendees learned the best ways to hoist and stack the 60- to 80-pound bales, how to cut half-bales for window frames, how to plaster, and more. Mundelein’s first-floor walls went up in four hours. “It was a community thing, like a barn-raising,” he says, but also an organic way to pass on the techniques of straw building. “Everyone who has a straw-bale house is open to sharing their experiences and how they built it. It creates a connection.”

But straw-bale owners can be over-proud, Mundelein says wryly. “We all feel we’re experts, because we’ve built one. Beyond the belief that building with straw is the right way of doing it, everybody is very attached to the specific way they built their house.”

One frequent point of contention is whether the straw bales should bear the weight of the roof and higher stories. Most straw-bale homes are “post-and-beam,” echoing conventional building with wood framing for the walls. The bales slide in between for insulation and wall thickness. But bale stacks can also be load bearing. Mundelein used “essentially no lumber” in his house to reduce the amount of new resources used in construction.

On the flip side, structural engineer Jeff Ruppert of Boulder’s Odisea LLC, which has consulted on almost every straw-bale structure in Colorado, steers people to post-and-beam. “Yes, load-­bearing walls are almost twice as strong as a framed wall, but it’s different than anything anyone has ever worked with,” he says. “A load-bearing straw wall won’t be plumb or level, even if you have a bead on it. Your contractor or carpenter will hate it.” Architect Brian Fuentes, of Boulder’s Fuentes Design, agrees. “Given the minute amount of wood it takes to bring posts down to the floor where the windows are—you have a window frame there anyway—it makes sense to go post-and-beam.”

Stylish Straw

Fuentes is one of only a few architects in Boulder County (and even across Colorado) who specialize in straw-bale homes. Introduced to straw building during college in Oregon, Fuentes immediately fell in love with its environmental and social benefits, and more notably, aesthetic appeal. With plaster coating thick bale walls, straw homes lend themselves to the soft, wavy shapes of Southwestern or adobe architecture. However, “it’s also possible to do anything with straw bale that we do with stick-frame,” Fuentes says.

Several of his current Boulder projects are modern homes indistinguishable from their timber-framed neighbors. But, he emphasizes, there are better ways of doing straw bale than emulating conventional buildings. Simple structures, for example, are easier to form with the oversized straw building blocks. And unmodified bales natu­rally make soft corners and undulating walls. “So every time you put in a straight line or sharp angle, it multiplies the cost of the house,” he says.

Red Feather Development Group’s straw-bale strategy is a testament to straw’s innate simplicity and form. The Montana-based group emerged to deal with a growing housing crisis on American Indian reservations, teaching tribes to build cheap, warm houses with community labor. The group’s “best buildings so far” are all straw bale, based on traditional Native American designs. One, a round building inspired by a Navajo hogan, avoids sharp corners almost entirely. All can be built with minimal professional expertise. “Straw bale is a really simple, down-home sort of technology,” Fuentes says. “It’s straw, and you rub mud on the walls. But it’s a really high-performance product.”

And, like Delcavo and Moser, many bale builders use straw’s high insulating perform­ance as a steppingstone to a truly green home. A prime example is Fuentes’ most recent project, a 3,300-square-foot house replacing a veritable dump dating from 1911 on North Street in Boulder. Owner David Adamson, who runs Eco-Build, a natural building products company, wanted a zero-energy house—one that not only requires no extra energy to heat and cool, but also makes up for all the energy and impact that went into the building process. Waste straw, plus the century-old timber to frame the interior walls, was a good start.

But getting off the grid meant using active solar photovoltaic panels and special window glazes to maximize passive solar heating, as well as other technologies. (Adamson cataloged any new material that went into the house, with a plan to offset the carbon use by purchasing and restoring Colorado prairie land.) It also meant paying for that technology. “Bales are cheap, so on a straw-bale house, you’d like to spend less,” Fuentes says. “That was one of the issues David and I really struggled with. We were trying to reduce that cost, but we were trying to get more out of the system.”

In the end, even if you stack the bales yourself, an energy-efficient straw-bale house costs about the same as a conventionally heated, wood-framed house. But savings do accumulate in the long-term. Typical straw bale homeowners spend about $400 less per year in energy costs than owners of stick-frame houses. If you’re off the grid, you pay nothing (saving another $1,000 or more per year). But new home builders frequently dwell on the construction cost, to the chagrin of straw bale owners.

“I do get tired of people asking me if straw is cheaper,” Delcavo says. “There’s a lot of value we get from this house that you can’t put a dollar value on.” The snug, silent interior, for instance, and natural walls that offer a connection to the earth.

Like all straw bale owners, Delcavo loves to talk about his house and its virtues. He and Moser have had plenty of intrigued visitors to their straw-bale creation during the past nine years, with a good number of them going on to build their own straw-bale homes. If the conversation has to start with a Three Little Pigs joke, so be it.

After all, would Delcavo trade his straw house for one made of bricks?

Not by the hair on his chinny chin chin.

Tyera Eulberg is former assistant editor of Boulder County Home & Garden Magazine. She hoisted her first bale when she was 14, and can’t wait to raise her own straw-bale house someday.

Bale Basics
	If you’re considering building with straw, here are some things to keep in mind: Grain: the most common types are wheat, oat, barley, flax and rice. But any kind of straw (including that from hemp, spelt or whatever fibrous plant is growing nearby) can be baled and built with. Tightness: Bales must be sufficiently compressed in order to form sturdy walls. To evaluate, lift the bale by the strings. They should lift less than 6 inches from the straw, and the bale should not twist or sag. Dryness: To keep mold out of your walls, use only dry bales. Bales should look “bright,” and feel and smell dry. Pests: Walls that offer openings, nests and food attract pests. Straw covered in plaster is short on all three. Make sure bales are mostly free of seed heads (aka mouse food). Where to Get It: Ask a local farmer—most will jump at the chance to sell straw instead of burning it, and you can avoid large costs (both environmental and monetary). Some farmers will use a wire baler upon request to mak especially dense bales for building. Resources: In addition to Boulder’s Colorado Straw Bale Association (coloradostrawbale.org), many people and groups post online information on straw-bale houses. A particularly fine resource is thelaststraw.org. —Tyera Eulberg

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