Wednesday, December 24, 2008

Looking Back to Move Forward

Every owner-builder I know sings the same mantra: If I had it all to do over again, I'd do everything differently. Don't get me wrong - I love my home, and am very thankful for it, especially as "the American Dream" eludes so many. Still, it's extremely hard to learn so many new techniques and realize that you could have done everything so much better. Not bigger, not fancier...but better.

Some of you know that I attended an intensive building workshop this summer at Solar Energy International (SEI) in Paonia, Colorado. Our primary instructor, Laura Bartels, is an amazing straw bale builder and the energy behind Green Weaver, her design, consulting, and education business in Carbondale. Laura had just returned from our nation's capital, where she had been working with Builders without Borders to build an eco-friendly information kiosk at the US Botanical Garden, and deliver free presentations and hands-on workshops to get these ideas out to the public.

Assisting Laura, we had Doni Kiffmeyer and Kaki Hunter, a husband-wife design-build team who specialize in earth bag buildings in the tradition of Cal Earth's Nader Khalili, who passed this year. Between our three instructors, we learned the age-old techniques of earth-bag building (1st photo), adobe brick making (2nd photo), straw bale techniques, mixing plaster (3rd photo), and making cob (4th photo). The common element in all of these techniques? Earth, of course. This area of study is often called earthen architecture, or earthen building, which is more accurate than "natural" building.

You might wonder why trees are absent from this curriculum. It's not that timber building is un-natural. Done correctly, it can even be sustainable. For example, the spruce bark beetle plague of the Kenai Peninsula converted miles of open forest to fields of dead conifers. As the beetle worked its way southwest, the lush and verdant spruce forests that defined the region turned to a rust-red brush-stroke across the horizon. These beetle-kill spruce have provided the lumber to build our homes, and the BTUs to warm them. I used the beetle-kill timber to side my home (5th photo). But with the best of that wood used and only the rotten remaining, procuring lumber from Canada or the Lower 48 is costly on multiple levels.

The benefits of working with earthen materials are myriad, but I most appreciated that they were local, and that I could use some of these techniques with the very soil on my own land in Alaska. For example, my property consists of a shallow clay lens, and there is lots of sand nearby, too. If I ever get around to building my root cellar, I could use the clay I excavate to fill earth-bags for the root cellar walls. With plywood at $50 a sheet, and concrete blocks at $15 each, using my own soil to build the walls sounds pretty sweet.

There is a building trend sweeping the western states and parts around the world, but there's not a whole lot about it that's new. In the US, straw bale dates back to 1886, with a one-room school house in Bayard, Nebraska. Cob is known back to at least the 13th century in England. Then there's adobe: California's magnificent missions, Chapel San Miguel in New Mexico, which was built in 1620, and the magnificent towers of South Yemen. So, the natural building "trend" is nothing new, it is simply a rebirth. Check out this tour of natural buildings here in the USA.

What's particularly tricky about working with these earthen materials is that there is no magic formula. Everyone wants the perfect recipe, but there is none. It's unique to each soil type, and that goes beyond merely the moisture, sand, clay, and gravel content. Each of those elements can have different binding properties based upon the parent material (like silica), the grain size and shape (round? angular?), the elasticity of the clay component, and a variety of other properties that define how well it binds. So, there's no way around testing your soil and experimenting to get just the right consistency. What's the right consistency? Alas, that comes with experience, that magic "je ne sais quois" that only the trained hand can detect.

There's a trick when it comes to working with earthen building materials if you live in cold climates. Earthen buildings breathe. The whole mechanism by which they keep mildew from forming and critters from embedding is by moisture transfer - a concept that is completely foreign to modern building science for high-latitude regions. In colder places, buildings are designed to be very tight, to keep heat in, and to keep "glaciers" from forming on the roof and eaves. Our buildings can be so tight that indoor air quality problems arise from the lack of ventilation. Vapor barriers are built into the system to prevent any moisture movement. Of course, if the vapor barrier fails, it's just as likely that you're locking moisture into your structure. Tight, vapor-barrier construction conflicts directly with the "breathable" quality of earthen materials. If you want to build an earthen addition to your home, or add a straw bale skin to increase your R-value, you'll mate two incompatible systems - one that depends upon zero moisture transfer, and one that relies on nearly complete moisture transfer. So for now, we cannot mix these techniques without taking on a tangible risk for rot, mold, mildew and, ultimately, failure.

Oh, if I had it all to do again.....

So for 5 days, we learned the inner science of clays, plasters, coatings, pigments, stability, emerging building codes, ensuring breathability, securing bales, load-bearing versus non-load bearing techniques, and more. I left with so many ideas, and the hope that I can somehow build an earth-bag greenhouse on to the southern aspect of my home. If not that, I at least hope to build a few cob benches, like these whimsical creations in Toronto's Dufferin Park. And at City Bike in Portland, Oregon. And the inspiring design flexibility and creativity that these techniques encourage, as shown in this video tour of cob features.

Check out this cool video, where natural building architect Scott Kelly walks us through a state-of-the-art efficient, low embodied energy office building.

It's hard not to be excited about this trend in perfecting and updating these techniques that, though not quite lost, seem to have been hiding from us for the past few generations.

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