Straw-Bale Construction

History

I n the late 1800’s, settlers in the Nebraska Sandhills region of the USA (an area with no trees and soil too sandy for sod walls) were forced to get creative in sourcing building materials for their homes.  The arrival of the modern, mechanical baling machine made many things possible, including the invention of the straw-bale wall system.  Covering the outside and inside of the bales with plaster (stucco) protected the bales and improved their air-tightness.  Residents soon realized the high level of comfort the walls provided.  Word spread, and many straw-bale buildings were built throughout the region and the world, including the Pilgrim Holiness Church in Arthur, NE (built 1928, pictured) and the ‘Maison Feuillette’ in France (built 1921), both of which are still standing today.

By the 1940’s, 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 1970’s and 80’s 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.

How it Works

I n 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.

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