Text of introduction for Design of Straw Bale Buildings

The oldest known straw bale structure in the world reached the century mark in
2003, an anniversary of both sentimental and technological significance. The historic
Burke house in the little town of Alliance, Nebraska (United States) would
not necessarily catch your eye as an architectural wonder, or even oddity, yet its
presence there is intimately connected to the book in your hands. Had that modest
little home and many like it not survived to this day, then straw bale construction
might never have caught the skeptical interest of a few builders, this book’s
authors, or the public at large.

Those first straw bale structures in the Sand Hills of Nebraska were built by European
settlers entering the area from the 1800s onwards. Having few other means
to shelter themselves, they were driven by necessity to improvise; there was little
stone or cement, the sod was often too sandy to cut or too valuable as cropland,
and most of the available lumber was what little had come on their wagons. Using
the newly invented horse-powered baling machines, they bundled the grasses
that surrounded them, stacked the bales to form walls, and applied mud plasters
inside and out. Many of those homes still exist in good shape, as do a few more in
other parts of the world where baling machines had appeared over the subsequent
decades. This was the birth of a promising and completely new building technology,
yet with roots in various historic forms of earth and straw-based construction
that were widespread in Europe. Nonetheless, as the Industrial Revolution spread
in the form of railroads and modern building materials, interest in straw bale
construction faded.

In the 1980s the American West witnessed a revival, initially sporadic, generated
by some obscure published articles and the scattered efforts of a few architects and
owner-builders. In 1989, some of those latter-day pioneers gathered in Oracle,
Arizona to play, collaborate, and imagine how best to build with bales; a few
newspaper articles followed, interest blossomed, and the straw bale revival suddenly
was and still is exploding in size. As more architects, engineers, inventors,
and builders began to try this new material, a variety of styles and techniques
began to emerge. There are now straw bale health clinics in Mongolia and China,
wineries in Australia and California, a prince’s palace in Saudi Arabia, a post of-
fice in New Mexico, a Buddhist monastery in New York, retail stores, schools,
police stations and high-end luxury homes in California, and thousands of houses
of every style all over the world. Field experience and laboratory experiments
have taught some basic lessons that will be articulated in this book, but straw bale
construction remains very much a developing technology. As is the case with
any building material, there is no “right way” to build independent of climate
and rainfall, soils and earthquake hazard, building usage, and architectural style.
There are many right ways to build with straw bales – and many wrong ways.
Many bale building techniques, first rediscovered almost entirely from a short article
by Roger Welsch published in the book Shelter1, were inherited from the first
Nebraska settlers. Steel or wood pins driven down through the bales to stabilize
them, for example, were codified in the first modern straw bale guidelines. But
“pinning” is no longer thought to contribute strength or be worth the trouble, and
has been largely abandoned. In any event, publicity fueled popularity, and to this
day public interest worldwide has stayed well ahead of engineering knowledge
about straw bale structures.

The explosive rise in interest has resulted in thousands of built straw bale structures
throughout the globe, and a small and increasing number of books on the
subject. (For more general discussions of straw bale construction, and access to a
wealth of photographic images, see the Resources section at the end of the book.)
To date, however, there have been relatively few resources to help architects and
engineers design straw bale structures to endure the driving rain, humidity, extremes
of hot and cold, fire, wind, and earthquakes that routinely cause the early
demise of buildings of all types around the world. In responding to the question
“How will this building perform?” we have relied mostly on intuition and anecdotal
evidence.

Now, with the completion of many tests in recent years, we have a much clearer picture
of how straw bale buildings behave under the normal range of stresses that affect structures.
This book is a review of all those tests and of the anecdotal knowledge gained over a
hundred years (particularly the last fifteen). It is also a studied effort to digest and present that
knowledge in a way that can be of practical use. This is architecture and construction at its
most elemental: we try things out, we make mistakes, we learn, we adapt, and we thus build
our knowledge of how to build. It may be that an architectural straw bale vocabulary will
emerge as our understanding of the material evolves – just as it did with stone, wood, structural
steel, and reinforced concrete – and the intent of this book is to lay down a rational foundation
on which to develop the architecture of straw bales.

The re-emergence of straw bale construction over the past fifteen years has occurred
within a particularly hospitable environment, in the United States and
around the world. Green building in general has become a commonplace term, referring
to the design, construction, and maintenance of buildings that are careful
in the use of material, human, and energy resources to create shelter, with great
regard given to protecting not only the building occupants but also the local and
global system of life from which those resources are drawn. Green building means
building with the welfare of future generations, not just this one, and not just human,
in mind. Straw bale construction, by virtue of being unusual and photogenic
– and thus the star of innumerable media pieces – has been the introduction for
quite a few people to the wider concerns of green building for healthy interior
environments, energy efficiency, and waste reduction. It is also a classic example
of what has been dubbed Industrial Ecology, i.e., the idea that one industry’s waste
can be another’s feedstock. What the farmer throws away, the builder turns into
warm, durable houses.

The Internet has also been key to the growth of straw bale construction, as the
sudden ubiquity of Web access has made it astonishingly easy for the nascent straw
bale community – for lack of a better word for a very loose-knit worldwide group
of inventors, builders, scientists, architects, and engineers – to communicate, collaborate,
and learn from mistakes. And, as straw bale construction remains almost
completely in the public domain, there is little protection of secrets or glossing-
over of mistakes. Quite in contrast with other building technologies that are
jealously guarded, the non-proprietary nature of straw bale building – with a few
exceptions – has kept innovation, refinement, and failures out in the open for all
to learn from.

Finally, it bears mentioning that straw bale construction is perhaps the most visible
part of a revival of interest in “natural” building, generally understood to mean use
of minimally-processed materials with roots in historic or indigenous (i.e., pre-
Industrial Revolution) ways of building. Before fossil-fueled engines enabled us to
move any material anywhere in the world, and to make building materials themselves
from oil, we had to build with what was at hand. The extraordinary range
of styles and material uses that evolved over the centuries is being rediscovered
for the ingenuity and experience that went into them. (See, for example, Built by
Hand2.) What are routinely derided as “mud huts” and “grass shacks” often, if not
always, turn out to be very effective means of shelter (as architectural conservators
the world over already know). The adobe buildings of the American Southwest,
the lime-plastered timber-frame houses of medieval Europe, and the Roman concrete
monuments, to choose just three examples, have all proven themselves to be
in many ways superior to the “modern” structures that now surround them. Thus,
building professionals who have taken an interest in straw bale construction have
been startled to discover that there is so much to be learned from the old ways
– that we have very nearly thrown out the baby with the bathwater in abandoning
everything old in favor of anything new. Perhaps the preeminent example
is what we’ve learned about the interrelationship of moisture and buildings. We
invented plastic sheeting and then figured we could shrink-wrap our buildings to
keep all the water out – and ended up trapping it in and getting great mounds of
mold. Ditto with cement plaster, which has been applied to ill effect over historic
earthen buildings around the world, and which can cause – and hide – moisture
degradation in wood-framed walls. Slowly we’re re-learning what our ancestors
had always understood: buildings get wet no matter what you do, so in your design
and construction, always provide a means for them to dry out. In the case of
straw bale construction, for example, this knowledge of the old ways has led to favoring
vapor-permeable earthen and lime plasters over more brittle cement-based
plasters, while utilizing modern steel or plastic reinforcing meshes and fasteners to
deal with earthquake forces.

This is not to suggest an anti-technology or neo-Luddite view of building so
much as to point out that, as with all other domains of life, it’s worth knowing a
bit of history. The most effective way of building any particular project employs
not so much primitive or modern, but appropriate technology. ( John F.C. Turner
best defined this by saying, “Truly appropriate technology is technology that ordinary
people can use for their own benefit and the benefit of their community
that doesn’t make them dependent on systems over which they have no control.”)
As the easy availability of fossil fuels decreases with the attendant rise in fuel costs,
there will inevitably be a trend towards building with what is near at hand. We
won’t return to “mud huts” and “grass shacks”; we’ll simply learn to be smarter in
the way we build, and we’ll eliminate the very concept of waste.

This book may be unusual just for advancing our engineering perspective on a
hitherto obscure building material: straw bales. It is also somewhat unusual for addressing
several engineering properties under one cover, i.e., structure, moisture,
durability, fire, and thermal insulation. This is reflective of the fact that a plastered
straw bale assembly is structure, insulation, air barrier, finish, and fire resistance
all in one – as opposed to most building materials, which typically perform only
one or two of the requisite functions of a building enclosure.
The book is also organized to reflect an emerging development in the way buildings
are thought about and designed. The past several decades have seen increasing
specialization in the architecture and engineering professions, spawned in large
part by rapidly increasing proliferation of and knowledge about building methods
and materials. A moderately large or complex project may have design architects,
project architects, landscape architects, construction administrators, disability access
specialists, lighting and energy consultants, interior designers, and engineers
of every stripe: structural, mechanical, electrical, civil, acoustical, etc. Each specialist
addresses his or her own aspect of the design, theoretically under the watchful,
knowledgeable, capable, and all-seeing eye of the project architect. Sometimes
the system works; sometimes it doesn’t. This is not said as a criticism of architects
so much as to point out that without some form of capable and holistic overview,
the designed building may not function as intended, or even fail outright. Those
who design with straw bales are generally aware of this, and thus have discovered
and embraced both collaborative design – working and communicating as a team
from start to finish – as well as the emerging body of knowledge known as building
science, which comprehensively considers the effects of temperature, moisture,
vapor, air flow, and structural stresses – along with aesthetics – in designing a
building enclosure or detail. You get the big picture, or you get problems: good
design is important, yes, but a pretty house that cracks, leaks and rots is no longer
pretty.

This is intended to serve as an engineering guidebook. It has been written as
much as possible to be accessible to any building professional, or even layman, but
will inevitably have sections that are obscure without an engineering background.
Nevertheless, in contrast with many other engineering texts, no problem-andanswer
sections are provided. More importantly, the book offers few cookbook
formulas that might delude the reader into a false sense of design confidence. It is
simply not yet possible to comprehensively delineate a prescriptive way of designing
or building with straw bales, if in fact it really is with any building material.
The technology, as mentioned, is still rapidly developing, so we have focused on
identifying rules where they have become clear (“Keep those bales dry!”). Otherwise
our aim is to present underlying principles by which the reader can work
out site-specific building challenges. Common sense, and a knowledge of local
culture and climate, have always been and will continue to be the overarching
guidelines for any building designer.

In the hundred years since straw bale building was first pioneered, the basic technique
has remained as straightforward as stacking the bales and plastering both
sides. Our knowledge of the material properties of these walls has blossomed in
tandem with the extraordinary revival of the past fifteen years, and we now are
now equipped, at least roughly, to design for any conditions. That there are enormous
environmental and energy-conserving benefits to straw bale construction is now without
question, so any strategy to move the construction industry towards a sustainable course
must allow for and encourage this intriguing new building technology. This text offers to
designers and builders a sound scientific and common-sense basis for exploring and
contributing to the development of plastered straw bale architecture.