In the early days, the stacked and plastered bale walls supported the load of the roof on their own (without wood posts). This type of wall construction, known as “load-bearing”, is still used to a limited extent on smaller 1-story homes. However, to achieve greater structural capacity and architectural freedom, the majority of straw-bale walls built today incorporate structural wood columns and bond beams (in various formats) to take vertical loads off the bales. These walls are sometimes called “non-load-bearing”, although the bales and plaster are still used to resist lateral loads from wind and earthquakes.
A traditional straw-bale wall assembly consists of only three things: exterior plaster, bales, and interior plaster. There are no plastic vapor barriers, house wraps, etc. The walls are naturally vapor permeable and extremely low in embodied energy. They can also help create a healthy, non-toxic indoor environment.
By the 1940s, the mass-production of cement and oil-based building materials provided an affordable, attractive housing “package” that’s still common today. Many of these homes strived to recreate the durability of natural materials like stone but used unchecked quantities of energy-intensive, toxic ingredients. Environmental awareness in the 1970s and ’80s led to a modern resurgence of straw-bale construction in the USA and worldwide. Today, there are straw-bale homes in all 50 states in the USA, and over 100 in Colorado alone. The introduction of Appendices S and R in the 2015 International Residential Code has further supported and encouraged the growth of straw-bale construction.