Building Your Own Home: The Benefits of Rammed Earth

Categories: Green Building
Posted on Thursday, March 26th, 2009 at 10:15 am by admin

My girlfriend and I often toss around the idea of buying or building our own home. We often find ourselves talking in circles about the advantages and disadvantages of each. For example, we’d like to buy an old home and fix it up because we like the idea of recycling a house, but why put all that money into something that was built without any thought toward efficiency and sustainability? We want to BEGIN with efficiency, not just tack it on. So we argue that building our own home would be cheaper and more sustainable, but then we shudder at the thought of developing previously undeveloped land. So what do we do?

We don’t want to build (or live in) an inexpensive inefficient hunk of 2x4s. What happened to building homes that would last for centuries and house generations of your family? Solid brick construction, a natural slate roof, full basements? It seems all the new developments with the ego-facades are built with the idea that a family will move in or out every 10-20 years. They’re certainly not homesteads. They’re so inefficient. They’re so toxic. They’re so … Jersey. In the grand scheme of things, they’re dressed up temporary emergency shelters. As John Abrams points out in this video, all the cathedral builders are gone. We don’t look past our own noses to future generations.

Luckily, I work at Chelsea Green and have access to a wealth of insanely great sustainable building and sustainable retro-fitting books that I can spin my head around these questions all day long. My current fancy is building a rammed earth home: sustainable, natural, durable, and cheap!

Read about how great they can be!

The following is an excerpt from The Rammed Earth House by David Easton:

There’s a certain magic one feels inside a house with thick earthen walls. It’s hard to describe, but easy to notice. Just take a step inside one on a 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 that’s a little harder to name. It’s quiet; the house feels solid and sturdy, calming, comfortable, timeless. Inside, you are reacting to the coolness emanating from the walls themselves and the buffering of ambient sounds, but inherently the “je ne sais quoi” of an earthen French country farmhouse or a California mission is actually a part of our evolutionary memory: We are hardwired to be at home in earth.

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 human tolerance for discomfort decreased, the 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 have grown up with the idea that a house is a lightweight box with walls assembled from thin sticks 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— fiberglass insulation—to fill the empty spaces inside the walls, floors, and roofs. Then as energy costs continued to increase, the industry invented another petrochemical product—Tyvek, a sort of plastic bag—to wrap around the entire house. The fiberglass insulation and wrapping 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 in which they were born. It made sense to invest in longevity if one’s 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 landfills, 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 around the building. 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. Decisions about what materials to use, whom to buy them from, and how far to transport them have an impact on the longterm 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 reconnect 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 U.S. 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 twentieth 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 percent 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. The answer may not be hard to find. 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 that are 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 groundbreaking 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, chemicalfree 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 the 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 “supertanker” 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; it’s an alchemy that I have always enjoyed. To other builders, it’s just plain hard work. But if you succumb to the magic of rammed earth, you won’t regret the effort.

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