Building Green: Energy Efficiency and Aesthetics From The Same Materials (Part 14)
This week's article will once again address the construction of the main house (the past few articles focused on construction of the workshop).
At this point in the construction process, framing of the house is complete and we can begin stacking the straw bales. For this task, I decided to enlist the help of some volunteer workers. Over the course of a weekend, I held a straw bale workshop. I had placed several fliers around town to announce this, and on the first day of the workshop, about twenty-five enthusiastic individuals showed up to lend a hand and to get some hands-on experience with these techniques. A workshop like this benefits everyone involved. The homeowner saves a great deal of time and money (in my case, eighty percent of the bales were placed during the workshop) because he or she is essentially getting free labor, and the volunteers receive free instruction on how to place the bales and other related skills. There is also a wonderful feeling of community when a group of people get together for a project such as this—the obvious comparison is that of an old-fashioned barn-raising. Even people with no house building experience are drawn to straw bale construction. They are intrigued by the do-it-yourself nature of these big building blocks that are actually made from wheat stems. (When wheat is grown for food or other uses, the stems are generally considered a waste product, so it's great when this material can be used as insulation in walls.) The straw bales make the walls nice and thick, and the process of stacking the bales is easily learned after a couple of hours of practice. The individual bales are placed in a staggered fashion (like laying bricks), and notches are cut wherever the corners of the bales must fit around one of the 4x4" wooden posts. This is done with an electric chain saw, which is powered by the photovoltaic panels on the roof of the workshop (discussed in previous articles). When only part of a bale is needed, a full bale can be split in half and retied with baling twine.
The bales are pinned in place with long shafts of bamboo, wood, rebar, or some other material. The pins are either placed on the outside of the bales or driven down from the top through the center of the bales. Exterior pins are the preferred method among straw bale experts but may not be permitted in your area. New Mexico, for example, requires interior pins. (At least this regulation was in effect at the time of my construction.)
Once stacked, the chain saw can be used to bullnose the corners of the bales around windows and doors. (This is really a matter of aesthetic choice, since some people prefer to leave corners sharp and angular.) With the walls now in a solid form, the interior spaces of the rooms can be experienced in terms of volume and scale. The spaces are now contained and have views visible through the openings for doors and windows.
There are only two conventional frame walls within my home. These were used for plumbing purposes, because it is not advisable to run pipes through straw bale and adobe. Any leak can cause moisture to seep into the walls, which is not good for any wall, but must be particularly avoided with straw bale. Besides, fixing any leak that does occur is a lot easier with a wood frame wall than a straw bale wall.
In my next article, I will talk about electrical wiring and more.
[This has been a guest post by Ted Owens, a green designer and filmmaker. More details on green building design and construction can be found on his website and in the Building with Awareness DVD and Guidebook. -Ed.]