Solar Energy Facts-Straw Bale Construction

People have been using straw one way and another for building purposes for thousands of years, but it wasn't until the late 1800's that they began making bales out of hay and straw. In the treeless sandhills of Nebraska around this time, some enterprising person decided that straw bales might make a good house. There was probably a lot of trial and error involved in the first few houses that went up, but eventually they got so good at building houses out of straw bales that some of these houses are still standing-over a hundred years later!

Straw is an agricultural byproduct, much of which is burned to get rid of it. In the United States alone over one hundred million tons is burned annually, which contributes drastically to air pollution. Our solar energy facts show us that using straw in a well thought out design is a low impact resource that benefits not only the homeowner but the environment as well.

There are basically two methods of straw bale construction; post and beam, where the straw is used for infill and the roof is supported by the post and beam structure, which can be made of wood, steel, or concrete. The other method of construction is load-bearing, where the roof is actually supported by the bale walls themselves. A top plate is laid on the bale walls and secured with strapping or metal rods that go all the way to the foundation. The roof is then fastened to the top plate.

Straw bale construction can be used almost anywhere in the U. S, as long as care is taken in wet climates to assure that the bale walls be kept dry. In areas where moisture is a problem special precautions such as: roof overhangs, good foundations, and starting the bale stacks up off the ground, are good ideas. Solar energy facts tell us there are a number of advantages to building with straw, some of which are: superior insulation, soundproofing, and a certain comfort from the combination of straw and plaster. The straw itself is cheap and plentiful in agricultural areas, and the bales are easy to build with, as they are stacked like bricks and then pinned together using rebar, wood, or bamboo stakes. For added strength chicken wire or welded lath is sewn to the bales and then the walls are earth plastered or stuccoed inside and out.

The cost of straw bale construction is comparable to stick and wood, depending on the amount of labor the builder can provide. A great deal of labor is involved in the plastering of the bales. The plastering on straw bale construction is very important. The breatheability of the walls is dependent on the proper mix and application of stucco or plaster. Some people choose not to use a netting on the outside of the straw, but to plaster directly to the straw itself. When using this option, the first coat applied is a thin clay slurry which is absorbed into the surface of the straw. Three more coats follow this to achieve a final thickness of from one to three inches. There are many different recipes one can use for the plaster, which include materials such as: earth, loam, sand, lime, and cement. Many of these recipes use mostly the earth found directly on the building site, combined with lime or cement.

Renting a stucco spraying rig would undoubtedly save a great deal of labor. Some people doing this work invite a bunch of friends and relatives and have a plastering party! It's important to have someone with experience or at least knowledge of the process. Workshops are offered in many parts of the country and would be a very valuable investment in time and money for any prospective builder.

Our solar energy facts show us that straw bale construction is an extremely important resource in many areas of the country. Habitat For Humanity has built straw bale houses. Mother Earth News has had several articles on building with straw. Here are some books on the process: Serious Straw Bale: A Home Construction Guide for All Climates(Real Goods Solar Living Book) by Paul Lacinski and Michel Bergeron, Building a Straw Bale House: The Red Feather Construction Handbook by Nathaniel Corum and Jane Goodall, More Straw Bale Building: A Complete Guide to Designing and Building with Straw(Mother Earth News Wiser Living Series).