Building with Straw Bales
We started over 15 years ago, designing and building our first straw bale home. Along the way, there have been the obvious jokes as to the big bad wolf blowing our house down. Coyotes, bears and deer have come near, but so far, no wolves. We are not Three Little Pigs. We are a family of four, embarking again on a straw bale adventure of building sustainably, one that we are hoping to share with others.
This time, our creative energy, help from family & friends has resulted in a ‘green’ artist residency and retreat space made out of straw bales. There are ecological, energy efficient, and economic reasons to build with straw.
Aside from the beautiful aesthetic of the rounded walls, deep window seats and the organic look of a building with bales, benefits also include using a natural, healthy, renewable and completely biodegradable material. The big thick walls translate to quiet, peaceful places.
There are two basic styles of straw bale construction:
- load bearing (Nebraska style) and
- non-load bearing (called infill)
We have used the non-load bearing style with the straw bales wrapping the post and beam. The bales are then covered with wire mesh strung tightly and the bales sewn to provide greater stability and strength. The last stage is the most time consuming of straw bale building and this is the plaster. The bales can be covered in plaster, cement stucco or other similar materials. We have used plaster for Hidden Creek.
We bought the straw bales from a local CSA farm in nearby Creston, B.C., reducing our carbon footprint that comes from transporting construction materials long distances, a key concern of green-building advocates. A short ferry ride brought the bales back to Nelson.
Using straw and lime plaster provides an alternative to health-threatening paints, glues and toxins embedded in manufactured building materials used in conventional building. Straw bales, unlike hay bales, contain no nutrients to attract pests.
Straw needs only one season to grow and needs little energy to produce. Straw bales result in super insulated walls that offer between R-43 to R-48 (twice to three times) the insulation of typical frame wall systems. This reduces the life cycle cost of a straw bale house and results in big energy savings. For our previous home in Fernie, B.C. we were in an energy efficiency study with Canada Mortgage and Housing Corporation (conducted by straw bale builder and consultant Habib Gonzalez) and were found to be 38% more efficient than the same size house conventionally built. The interior plastered walls of our house increase the “thermal mass,” which helps to maintain a constant temperature within the house.
Plastered straw bale walls have been proven to be a fire- safe envelope with a typical 2 hour fire rating. According to treehugger.com, engineer and straw bale advocate Bruce King, paid for an insurance-required test of fire resistance of straw bale walls,whereby “workers fired up a super-hot gas furnace next to a wall stuffed with straw in hopes of calming skittish insurers, bankers and building inspectors who have been reluctant to embrace big buildings insulated with bales of dried grasses.” The test wall satisfactorily withstood over two hours of 1,700-degree heat and the following hose-down.
Using straw as insulation can reduce construction costs by allowing the owner builder to build a large portion of the house, thereby reducing labour costs from specialized workers needed to build a house. Depending on choice of siding, type of insulation and interior wall finish, using straw has the potential to reduce material costs as well. Applying a reduce and re-use mentality to the entire building, allows one to make financial decisions that brings costs down.
Straw bale building brings friends and family together for bale raisings. Just like old fashioned “barn raisings”, we have held a straw bale raising for each home, which is a wonderful tool to teach others about sustainable building methods. The raisings promote a fun, hands-on, empowering, community experience. To see details of how to build with bales and incorporate green building methods into your home, visit www.dreaminggreen.ca