While straw for roofing and insulation is an ancient practice, the known use of straw bales as a wall system in the US dates to the early 1900's. Straw bale homes built in 1903 are still in use in Nebraska and South Dakota. In the 30's a straw bale mansion was built in Arkansas and is in use today as a museum. Contrary to the stigma bequeathed by the first little pig, straw bale exterior wall systems have the mass, cohesion and density to ensure a long lasting solid assembly. Also, the density of the bales must be construction quality and the baling string must be polypropylene twine or wire.
Straw has low embodied energy compared to other insulating materials.
The same insulating value in expanded polystyrene will contain approximately 92,200 BTU per square foot of wall area. Embodied energy for one square foot of R42 in fiberglas batts will be approximately 23,300 BTU's3 . Straw also has a negligible waste factor for deconstruction. Straw bale buildings have two construction styles. An infill style relies on a post and beam frame to carry roof and floor loads.