There’s a kind of magic to living in houses with thick earth walls. It’s hard to describe, but easy to notice. Just take a step inside one on some hot summer day and you’ll feel it immediately. It’s cool of course – everyone knows adobe houses are warm in the winter and cool in the summer – but there’s something else to the feeling, a little harder to put your finger on. It’s quiet, feels solid and sturdy, calming, comfortable, timeless. Physically you are reacting to the radiant heat or coolness emanating from the walls themselves and the buffering of sounds, but inherently the “je ne sais quoi” of a French country farmhouse or a California mission is actually a part of our evolutionary memory. We are hardwired to be at home in earth. Why resist it?
The idea of what makes a house has changed as much over the millennia as what a house is made of. Long ago shelter was, well, shelter. Then, gradually it evolved. As man’s tolerance for discomfort decreased, his desire for features like warmth, spaciousness, and eventually style, increased. At first houses were made of whatever was available, usually raw earth and raw wood. Over time, a range of manufacturing processes were developed for modifying earth and wood into other shapes and forms. Fired bricks and clay roof tiles are made of earth. Cement, concrete, stucco, and sheetrock also have their roots in Earth, since each is the result of mining and processing minerals. The timber industry has progressed from hand-hewn logs to sawn boards to framing lumber and now even to wood chips glued back into the shape of boards.
Most Americans today have grown up with the idea that a house is a lightweight box with walls assembled from thin sticks then covered on both sides with even thinner skins. (Some societies think of this as a tent.) The floors and roofs are also built of sticks with equally thin skin coverings. As energy costs increased, builders started using an expanded petrochemical substance to fill the empty spaces inside the walls, floors, and roofs. Then as energy costs continued to increase, the industry invented another petrochemical product, this one a sort of plastic bag to wrap around the entire house. The fiberglass by Johns-Mansville and the Tyvek® by Dow Corning are intended to reduce heat loss through the building elements. The image this conjures up for me is of wearing a fiberglass sweater encased in clear plastic wrap. This is a far cry from the magic of thick earth walls.
Not that long ago, houses were built to last for generations. People actually lived in a house long enough to think of it as home. People died in the same house where they were born. It made sense to invest in longevity if your children, grandchildren, and even their grandchildren would be living there. Times have changed of course, and in our fast-paced world few of us expect to die in the same city we were born in, let alone the same house. This doesn’t mean, however, that we can’t still appreciate the special qualities of a house built solidly enough to last for several hundred years.
Think of the savings in natural resources that would result if today’s houses were built to last longer. We could reduce the need to demolish houses and bury them in the landfill, and we wouldn’t need to harvest and process virgin resources to rebuild them. A structure constructed of solid materials, whether earth, brick, concrete, or stone, requires a larger investment on the front end, but as the generations roll by and stick houses roll into the landfill the environmental benefits are expressed in healthy dividends. Over time a building settles into its site, creating a sense of attachment and belonging. Trees and shrubs grow to maturity. Successive occupants make their individual contributions to the personality of the house.
This book is about building a house for longevity. It’s about a shift in attitude that takes into consideration the effects our choices have on future generations. The decisions of what materials to use, whom to buy them from, and how far to transport them each has an impact on the long-term health of the planet. Even though you may one day move out of the house you have built and away from the garden you nurtured, the attitude of building for the future can benefit everyone.
The techniques described in this book are compiled from thirty years of experimenting with ways to build houses that grow out of their landscape. I’ve been on a personal mission to re-connect people with natural materials and resources available on site. The material I am drawn to is raw earth. Most of this book deals with techniques for how to build using earth, primarily rammed earth.
In the mid 1970s, I was making plans to build my own house. Since I had far more time and energy than I had money, using a free resource, earth, for building the walls seemed logical. I had come across articles about the use of soil and cement by the US Army Corp of Engineers during my studies in the civil engineering department at Stanford in the late 1960s and I had even conducted some small testing of soil-cement. In terms of load-bearing walls, however, I had no knowledge of any earth wall system other than the sun-dried adobe bricks used to build the California missions. When I was young, my family traveled to all the missions, teaching us about California history. I remember how those big, shady, cool buildings felt inside. Perhaps it was those early impressions that inspired my life’s work.
I discovered rammed earth while looking for more information on adobe. What I found were dozens of old articles about this other method for building earth walls. As it turned out, the rammed earth technique had enjoyed widespread popularity during the first half of the 20th century. I obtained copies of the current information – Ken Kern’s The Owner-Built Home and Australian George Middleton’s Build Your House of Earth – and many other old publications dating as far back as 1780. What I read, that moist soil compacted directly into movable forms yielded immediately load-supporting walls, seemed too good to be true. As an industrial engineer, I was always working toward increasing efficiencies, and with no sticky mud, no waiting for the bricks to dry, no mortar to mix, and no bricks to lay, rammed earth seemed like a big improvement over adobe. I calculated rammed earth would use one-fifth of the water, one quarter of the mixing time, and less than 2% of the drying time. Then I asked myself the question, if this technique is so much more efficient than adobe, why isn’t it in wider use?
Thirty years and a million cubic yards of moist soil later, I’m still asking myself the same question. For one thing, rammed earth is a lot of work. As labor costs rise, labor saving systems dominate the building industry. The trend is for lighter weight elements, quick to assemble and as close to finished in the factory as possible. The goal is to reduce the on-site labor costs and decrease the total number of days spent from ground breaking to owner occupancy. The problem with this method of building is that with the primary emphasis placed on speed of construction, decisions of what materials to use and where to buy them tend to be driven by the bottom line rather than by the more important criteria of sustainability and environmental responsibility.
Ever since the 1970s, there has been a segment of the architectural community and the home buying public that has remained committed to environmentally responsible solutions, but it was small in size and limited in voice. The manufacturers of building materials had no financial motivation to improve their products, either to reduce the chemicals that went into them or the energy expended in processing them. As this book is going to press, however, a strong resurgence of interest in green building methods and materials is underway. Judging by the articles in architectural magazines and trade journals, it is apparent that energy conservation, chemical-free materials, natural light and ventilation, and CO2 reduction are now on the A-list of design guidelines. Judging by the advertising in these same publications, it is patently obvious that industry senses a tremor in the force. Is it the realization that global warming is not a myth or is it that one day we really will run out of oil? Are there sufficient profits to be made in the green building movement to initiate a change of course for the “super tanker” that is the construction industry?
Unfortunately there is limited opportunity to capitalize on earth construction. Raw earth is, after all, practically free. The process of converting it into finished walls presents a few opportunities for mechanization and hence profits, but not many compared to manufactured houses. It is yet to be determined what role thermal mass can play in mass-produced housing. If economics favor longevity over speed, the tortoise over the hare, then perhaps earth, be it ever so humble, will at last have its day.
Converting raw earth into human habitat possesses a beautiful simplicity, a kind of alchemy that I have always enjoyed. To other builders, it’s just plain hard work. If you succumb to the magic of rammed earth, you won’t regret the effort.