Decide on a simple design. A small, one story structure is ideal for a straw bale building. Incorporate a small number of windows and a main door. Too many openings can leave the structure unsteady, but incorporating a few will help the sun to passively heat the building. Choosing to leave the floors earthen will keep the structure cool in warmer weather. A shed roof design is popular for small straw bale constructions because it is easy to assemble and will help protect the straw bales from direct moisture.
Lay the foundation. Laying the foundation for a straw bale structure is similar to traditional building methods. Sometimes an intricate foundation is not needed, especially for earthen floors. Laying an earthen floor foundation begins with washed gravel, which your pour into the space. You then top the gravel with about 2 inches of sand. Next, you lay down a plastic liner and pour another inch of sand on top of it. You then take compressed earth, which contains clay, sand and compressed gravel, and push it into the space. Often times, you can complete this process with shovels and man-power, but if you want, you can employ a bulldozer.
Stack the straw bales in a running bond according to the structure design. A running bond is formed when the bales are stacked in a staggered pattern, so that they do not create a straight column with a running vertical joint, which could lead to instability. Once you are finished stacking the bales, the resulting walls should resemble a traditional, brick stacked wall. Install wood frames to incorporate windows and doors into the structure. At this point, you can also install electrical wiring and plumbing, if desired.
Apply chicken wire across the entirety of the walls, on both the inside and the outside. Staple the chicken wire into place.
Using a trowel, spread a base coat of earthen plaster onto the walls. Let the plaster dry for at least 24 hours. The plaster will need to be moistened before another layer is applied. To moisten, apply water with a sponge to a small section before application. Moistening a 5x5 feet area at a time will keep it from drying out before the second layer is finished. Repeat the process one to three more times, depending on the smoothness of the layer. The last two layers should be free of cracks.
Install the windows, doors and roof. Allow the structure to settle for at least one month before decorating or placing stress on any part of the building.