Fortunately, the straw bale building community is remarkably open source, freely sharing ideas, successes, and failures across states, provinces, regions, and countries, so good ideas catch on and not-so-good ideas fade away.Because of this broad cross-pollination we have much greater awareness of many different successful ways to build with straw bales—laid-flat, on-edge, or on-end, in any number of framing systems, with a variety of lateralforce resistance systems (shear walls). More and more builders are using bales stacked on-edge because there’s an improvement in R-value per inch, and the walls are not quite as thick—a good solution in urban areas where small lot sizes constrain building size. Many builders are turning to structural designs that simplify construction, and have developed efficient ways to address once time-consuming aspects of the straw bale wall assembly. In short; building with bales has matured since the revival of the late 1980s.  

Quite a lot of seismic, thermal, and fire resistance testing was done around twenty years ago, has been supplemented since, and much of that is now well known among designers and builders. We have a much better understanding of the building science of how these structures perform.

Probably the biggest game changer has been the International Residential Code’s Appendix S Straw Bale Construction. Code jurisdictions can adopt it, and even where they don’t, building code officials, designers, and builders alike can look to it for guidance. CASBA members played key roles in the development of this code, worked on it for a decade, and we were able to print the entire code in the book—most convenient!

On the near horizon we’re seeing prefabricated straw bale panel buildings. Already in Europe (England, France, Germany) there are three, four, and five story straw bale buildings make with prefabricated panels. This approach holds some promise to lower labor costs and speed construction.

Advantages depend on what you value. If you value

• spending your dollars locally to use a non-toxic, low-embodied energy, annually renewable building material that sequesters (stores) carbon,
• the aesthetics of thick-walled construction and hand-crafted plaster finishes and the resulting benefits of more stable interior temperatures,
• better indoor air quality,
• sound dampening walls,

…then building with straw bales holds a lot of advantages!  

But these advantages come with trade-offs. If you don’t particularly value these things, e.g. you’re not as concerned with what’s in or on your walls or where it came from so long as it performs as designed and meets your budget goals, or you don’t see your house-building decision in the context of making a significant difference in the world, or you don’t want to trade-off interior living space for thick walls, or you have had your heart set on a house with a parapet roof (nothing to shelter the walls from rain) since you visited the ruins of one in the American Southwest, then you may not view straw bale construction as holding any advantages.  

While builders may have a preference for the types of straw they use (wheat, rice, barley, oats, rye, et. al.) the building code doesn’t differentiate between them so long as the bales meet minimum density and maximum moisture content requirements. They must be at least 6.5 lbs. per cubic foot, and no more than 20% moisture content at the time they are placed in the wall. I have used rice, wheat, and barley straw; all of them produced well insulated, tight buildings. Each of them has trade-offs. Rice straw has more silica so it’s somewhat more resistant to moisture degradation, but it’s also harder on tools and can be very dusty. Wheat straw can have a rougher, scratchier surface because of the way it’s baled, so many wear long sleeves when handling it.  

In my experience any of the straw types can be used in any of the bale orientations in the wall, or in any of the load-bearing or post-and beam framing systems. In other words, the type of straw doesn’t influence the design or construction method.

The more important issue with building-quality bales, in addition to being dry and dense, is that they are not made of straw that has been flail chopped or partially shredded by a rotary combine harvester. When you cut the strings these bales disintegrate into short straw pieces—which makes them difficult to resize and notch. Look for a supplier who uses older style cylinder and straw walker combine harvesters because these machines damage the straw the least. Bales from this kind of baling equipment will separate into distinct “flakes” when the string s are cut.

I’m reading two questions here, and both are important to address. The book doesn’t really get into either. The first has to do with why some people build with straw bales, and others don’t. This was a panel discussion subject at CASBA’s recent conference, because many of us are frustrated that more people—even those who approach us wanting to build with straw bales—end up going in a different direction.   It’s a complicated subject, and there isn’t a consensus on this answer, but it ultimately comes down to what they value. There are a lot of reasons build with straw—we cover many of them in the first pages of Chapter 1 Why Build with Straw Bales?: plastered straw bale walls create beautiful spaces, provide a sense of security, possess great insulation and thermal mass characteristics, use a building material that is often locally abundant and annually renewable, which also has the lowest embodied energy of any building material, and stores carbon more efficiently than any other building material, is natural and non-toxic, and highly fire resistant, and can create super energy efficient structures if thoughtfully designed and carefully built. Generally, the more of these reasons that potential clients embrace—the more these reasons resonate with them, appeal to them, or align with what they value—the more likely they are to build with straw. Some people feel so strongly about these personal and societal benefits that they are willing to make compromises and sacrifices around building size and design features in order to live in a house made with plastered straw bale walls. We might call them “early adopters” even though the straw bale building revival began over thirty years ago.

On the other hand, if potential clients are interested in building with straw bales but only if it costs less than other methods of construction, or only if they don’t need to compromise on the building design to better suit the straw bale walls, there’s a pretty good chance they’re going to build with something else.

The second, broader reading of your question has to do with how we make building with straw bales “normal” instead of “novel.” To get there, we need to make it easy to build with straw bales—much easier than it is today (which is much easier than it was twenty years ago!).  

We overcame a huge barrier when the International Residential Code’s Appendix S Strawbale Construction became available in 2015. A decade in the making, it has been adopted by a half dozen states and cities in the U.S., and is available for adoption by building code authorities anywhere. Where it hasn’t been adopted it can be used under the code’s Alternative Materials and Methods of Construction section. We need more code jurisdictions to adopt Appendix S!  

Finding experienced builders is a huge barrier. I field calls from all over Oregon and much of California from people looking for a builder—there aren’t any where they live, and they aren’t up for a do-it-yourself adventure. I suspect this problem extends far beyond Oregon and California. That may explain why there are a lot of straw bale owner-builders. Until more mainstream builders include straw bale construction in their “tool chest” of green building options, there are going to be comparatively few straw bale structures built each year. Recent developments in prefabricated straw bale panel systems—available in parts of Canada, England, and Europe—hold a lot of promise because conventional builders are already familiar with SIPS and other prefabricated construction techniques.

We also need wider availability of accurate information about how these buildings perform, and how to build them. CASBA’s book is the most recent of many books about building with straw bales that seeks to de-mystify straw bale construction, and we hope it demonstrates the adaptablity of this remarkable building system.  

Part of our challenge is that the defining component of a straw bale building is a locally produced, widely available by-product of the agricultural industry. The supply is quite distributed, which has a lot of appeal, because grain crops are grown just about everywhere. But it also means that straw bale building—or building anything with straw (lights-straw-clay, blown-in-straw, etc.) doesn’t have an industry sponsor like conventional building materials (think Portland Cement Association of America, or the petroleum and chemical industry folks behind all sorts of foam insulation products, or the many timber industry associations that pour financial resources into research, development, and marketing). Building with straw has a few non-profit groups like CASBA advocating on its behalf; gaining mindshare has been a slow process, but every year more and more people recognize the connection between their environmental footprint and how it impacts the world we all live in.

Approximately 40% of all energy used in North America goes into heating, cooling, and operating buildings. Nearly 10% of all energy used in North America goes into the production and transportation of building materials. Wow! Each year, almost 50% of all the energy consumed in North America is related to buildings we live in or work in. Many straw bale buildings are so energy efficient that they are Net Zero in their energy consumption and contain far less embodied energy than similar energy efficient conventional buildings. We have the ability to reduce how much energy we pour into and use to operate buildings, yet every day it seems we learn of an even more urgent need to reduce greenhouse gas emissions or face irreversible consequences! What’s up with that?

Upton Sinclair wrote “It is difficult to get a man to understand something when his salary depends upon his not understanding it.” I often paraphrase this to “It is difficult to get a society to understand something when it’s lifestyle depends upon not understanding it.” We all have “life style” expectations shaped by the society we live in—what we eat, how we dress, how we travel from place-to-place, what we purchase, the size of our homes, what we think of as “comfortable” or “convenient.” These are the “norms” we live by—and we cling to them even as we have the power to change them.

My hope is that a rapidly emerging awareness of our individual impacts will make us re-think many of these norms, and realize that straw bale buildings (or super energy efficient buildings made with any carbon storing building materials) are one important facet of a much larger approach to living a truly sustainable life on this planet.