Nestling "Walden-esque" next to its north woods pond, the Gundersen home takes its aesthetic cues and its structure from its natural surroundings. |
Learning With The LandStraw Bale and Agrarian ArchitectureRoald Gundersen; La Crosse, Wisconsin This article was first published in the Fall 1997 edition of The Last Straw, a resource journal for straw-bale construction. They can be contacted at PO Box 42000, Tucson, AZ 85733.
Straw-Bale Insulated A-Frame |
Working on Biosphere 2 gave me insight into what I really considered environmentally
appropriate building. I came back to Wisconsin to explore a more accessible form
of "ecologically active" or "living" architecture than was available in the Biosphere
project. Solar greenhouses and agrarian architecture are natural points of departure as buildings welcoming life other than human. By inviting life, particularly plants and soil bacteria, into our buildings, we can clean and recycle our air, water, and biological wastes onsite while producing food, solar heat and light. Extrapolate this integration of ecology with architecture from rural, to suburban, and even urban buildings, and - I believe - we could see the dominant predacious or parasitic forms of human ecology evolve into more photosynthetic and ecologically diverse cultures. My point of departure is at America's grass roots: the family farm, a culture still alive and growing in Wisconsin. I see the solar greenhouse as the "new barn" at the heart of diverse organic farms growing crops year round. I see "sustainable" architecture in the old farm buildings throughout Wisconsin, built from locally-abundant materials. This is the work I'm building on. As with these buildings, my palette is locally-abundant rocks, dirt, sand, water and fast growing plants, primarily grasses and trees: hence poplar-pole frames and straw-bale construction... |
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In 1993 my wife and I built a straw-bale insulated A-frame near La Crosse, Wisconsin.
The 946 square foot home is built from site-harvested and peeled poplar and linden
trees. We dried and bolted the poles together into equilateral triangle frames 24'
on each side. We spaced the frames every two feet on center. Metal lathe and gypsum plaster
span between the frames, creating a ferro-cement shell over a wood frame. We mined
gold and orange-colored sands near the site to give the plaster finish a glowing
integral color. Plasterers whom we spoke to said plaster over a ductile wood frame would
crack like crazy. To date it has only hairline cracks at the eight-foot seams between
lathe sheets. |
Installation of the straw-bale insulation was the fastest and easiest phase of construction.
First, before the bales were placed, we laid a 6-mil polyurethane vapor-barrier outside
of the plaster and pole frame. We then stacked and packed the straw bales up the sides on exterior benches which are supported on the floor beams or straps attached
to the shell. The benches were also very useful as scaffolding during plastering.
The strap ends doubled as supports for the roof purlins and metal roofing. The bale
stacking took six people about five hours to place over 300 bales up to a height of
30 feet. The bales reposed into the sixty degree angles of the A-frames. It was stable
enough to climb, which we did during packing. The roof rides on the roof purlins,
away from the straw by an inch or two, providing ventilation of the straw. In my annual
inspection of the straw, it remains very dry and apparently unaffected by our humid
upper Midwest summers. I plan to monitor the humidity in the straw more rigorously
with meters. |
Thin-shell structure being constructed.Close-up of thin-shell structure underway. |
Rising stately from the site, yet still in harmony with it, the Gundersen home seems the essence of "home" and "shelter" in its northern woods surroundings. |
Dappled daylight streams through the south glazing of the A-frame structure, highlighting the peeled wood balcony and stair railing. |
Pole-frame of greenhouse, showing lithe structure awaiting bale-infill insulation. |
After dragging the trees to the site, I notched, bolted, erected and laterally-braced
the pole frames. We pneumatically stapled wound wire fencing over the north part
of the shed roof frame. We had a baling party with high school students. Bales were
stacked in straight columns in wire valleys between the poles. The wound wire held the
bales in place well, but we also had a sill plate which we packed the bales against.
The seams between bales were stuffed with straw flakes requiring most of the roof
baling effort. We then laid 2x4 roof purlins across the bales, roughly leveling them with
more straw flakes. |
A major revelation I had in working with poles was how much stronger natural wood
was than dimension wood. Wood in its natural state has its concentric fibers intact
throughout its length. In milling, lumber loses its concentric and continuous fiber
structure and is much more subject to breakage. Also, milling a 2 x 4 creates 80-90% waste,
requiring a tree of sufficient girth and age, usually no less than 40-60 years old,
before lumber can be milled. Almost all the trees we used were less than 20 years
old and two to three times as renewable. Foresters usually waste these trees in thinning
a forest. We could use this waste stream for pole-frame structures while we improve
the forest stand for mill timbers. The huge waste stream from the milling of dimension
lumber has led, in part, to the creation of glued particle- and chip-board products
that deteriorate rapidly with humidity and often release toxic formaldehyde compounds. |
"Agrarian architecture" finds its expression in the sweep of the solar greenhouse, rising in harmony with the forms of the site's natural vegetation. |
Approach to the site emphasizes the importance of the agrarian to the project, as the solar greenhouse opens up to the south sun. |