Deep Roots, Strong Branches: Whole Tree Architecture

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Architect Roald Gundersen shaped the roof from wind-bent trees to mirror the hills of southwest Wisconsin’s Driftless Region.
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Architect Roald Gundersen and homeowner Marcia Halligan at the 81-acre Chrysalis Farm
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Tucked in a corner nook, Marcia's desk seems to grow from the support of sturdy willow branches.
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A south-facing glass wall overlooks some of the homeowners' favorite views of the gently rolling Wisconsin landscape. The windows also let in sun for natural light and passive-solar heat. Inside, a mezzanine, crisscrossed by graceful branches, anchors the home's central open space.
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In the upstairs bathroom, floors are local rock and wood milled from trees on the farm.
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In the dining room, which shares space with the kitchen, every meal comes with the opportunity for all sorts of wildlife viewing.
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Load-bearing hickory (on left) and soft maple trees (on right) weave throughout the ceiling into the room upstairs. The kitchen cabinets came from a burr oak skidded by Marcia and Steven's horses and milled at an Amish sawmill 16 years ago.
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Marcia's bed is framed with birch trees, which recall fond memories of her youth. A cedar drawer beneath provides the foundation for the mattress. She can see the river from her balcony.

When selecting trees from their southwest Wisconsin property to use in the construction of their new home, farmers Marcia Halligan and Steven Adams passed over the stately oaks and the sturdy maples, choosing instead the weak and diseased trees. They didn’t need the forest’s strongest old-growth trees for their house, built using architect Roald Gundersen’s revolutionary Whole Tree Architecture. His technique uses whole, unmilled, “Charlie Brown” trees–in this case, weedy box elders, slender ironwoods, invasive black locusts, wind-bent hickory and diseased elms–to create sheltering, graceful homes while preserving mature forests around them.

“There’s a feeling in our house like we’re in a grove of trees,” says Marcia. “There is all this tree energy. It’s very beautiful and very nurturing.”

Rooted in place

Biodynamic farmers Marcia and Steven bought the 81-acre land just outside Viroqua 23 years ago. From their first walk through the rolling woods and pastures, Marcia felt a connection to the place. “Sitting on the ground with my eyes closed, I felt my roots sinking down into this earth,” she says.

Calling their new home Chrysalis Farm, the couple moved into the drafty, 19th-century farmhouse that stood on the property. Initially built as a log cabin in the mid-1800s, the house had grown over the decades in the hodgepodge fashion of so many expansions gone bad.

Eight years ago, they began planning a new house, which they hoped would honor their spiritual bond with the earth. They researched several building styles, including round, straw bale and cob houses. Then a friend suggested they take a look at a home that architect Roald Gundersen had built with whole trees. Marcia was struck by the simple grace the wood lent the structure. More importantly, she recognized that she and Steven already had an abundance of the resource they would most need: local trees.

A new look at wood

Gundersen began building with whole trees when he returned to Wisconsin after working for three years on Arizona’s Biosphere 2, an enclosed ecological system used to study global climate change. While there, he’d come to understand the importance of building with local, natural resources.

“In Wisconsin there are a lot of trees falling down, and no one is using them,” Gundersen says. “Going to the lumber store and buying Pacific Coast lumber never made sense to me. I started to understand that we should look at how we use wood instead of just saying we shouldn’t use it. When we cut down and mill the old, wise trees that have survived many storms, diseases and droughts, they can’t reproduce themselves. We’re really taking away wisdom for the future.”

Thinning diseased, invasive and wind-bent trees is more akin to gardening, Gundersen says. And because whole trees are stronger than milled ones, he uses trees that conventional builders typically overlook. “Trees make really strong curves,” he says. “This is a whole frontier of design that machined building materials can’t touch.”

Slow, local building

At Chrysalis Farm, Gundersen walked the wooded acres, selecting each tree to serve a particular purpose. Steven is fond of hickory trees, so Gundersen used it to build his room. He filled Marcia’s room with birch, which reminds her of her childhood trips to northern Minnesota.

Gundersen’s crew built cabinets from old burr oak that had been stored in the barn for years, and a local sawyer milled willow trees for trim and pine for flooring. “Willow isn’t a hard wood,” he says. “I talked with a lot of woodworkers who had never seen this wood before, and they were surprised it has such an amazing grain. It looks like an Impressionist painting.”

Whole branching box alder and elm trees frame Marcia and Steven’s 2,160-square-foot structure; the poles framing the second floor and roof also were harvested from the land. The roof is made of wind-bent tree beams; the rafters are aspen trunks harvested from a neighbor who was replacing a stand with fruit trees. Spanning the rafters is a ferro-cement shell made from Ecolutions hemp, a vapor barrier, wire mesh and stucco. Straw bales overlaid with curved 2-by-4 wood purlins (throw-aways from a wood kiln) insulate the metal roof. “It’s strong, rigid and fire-resistant,” Gundersen says.

To harvest the wood, Marcia and Steven’s draft horse team skidded trees to the house, and a local miller used a bandsaw powered by recycled vegetable oil to rough-cut the logs into lumber. Gundersen’s crew dried the trees and lumber in a solar kiln and re-sawed wood for cabinets, trim and framing.

“It’s sort of a ‘slow food’ process,” Gundersen says. “But you’re not just building a house, you’re building a local economy. On a conventional house, about 50 percent of costs typically go to labor. On this house, the ratio was closer to 75 percent labor with 25 percent material costs. That’s an important aspect of natural building–it can be locally sourced from within the community.” 

Whole-tree architecture is also economical. Marcia and Steven built their three-bedroom home for $200,000 (about $100 per square foot for finished space)–well below the national average for a custom home (about $135 per square foot).

Straw bales and solar power

Gundersen built three of the home’s walls using straw bales and finished them with a coating colored with green sand from  the cliffs of a nearby river. The south-facing wall has passive-solar windows and a greenhouse where the soil and plants clean exhaust from the bathroom, kitchen and laundry. 

The sun, a woodstove and in-floor heating supplied by an on-demand water heater warm the home. The couple relies primarily on solar-electric power, with grid-supplied backup. They plan to be completely off the grid in the future.

Marcia and Steven’s unique home garners interest and attention from just about everyone who sees it. Recently, Marcia stopped by the post office and the clerk inquired about her house, confessing that she’d found it very strange during construction and couldn’t imagine what the result might be. But as the house grew, so did her opinion of it, and she became, in Marcia’s words, “Favorably impressed.”

It’s a sentiment Marcia and Steven hear often. “People come to visit and they never want to leave,” Marcia says. “We have open houses, and people just hang around.”  

The good stuff

• Straw bale insulation walls and roof

• Solar electric system

• Passive-solar window wall with black-locust shade balconies

• Locally harvested wood, stone, sand and straw

• Recycled windows, doors and wood

• Natural linoleum floors (Marmoleum)

• Living Machine greenhouse technology to clean exhaust from the bathroom, kitchen and laundry

• Sawmill powered by recycled vegetable oil

• Logs and trees pulled by farm horses

• Finish wood dried and milled on site

• AFM Safecoat low-VOC, water-based paint and urethane seal

• Ecosolutions hemb fabric ceiling used to create superinsulated straw bale roof

• Energy-efficient, water-saving appliances