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Overview
Build economical and resilient earthbag structures using simple tools and techniques.
Earthbag construction—building with polypropylene bags usually filled with earthen materials—is a versatile, easy-to-master, low-impact, and highly durable form of building, suitable for structures from houses to root cellars.
Containing over seventy-five photos and illustrations, Essential Earthbag Construction is a practical guide to this affordable method of building. Going well beyond the scope of other sources, this indispensable manual is packed with all the information you need to determine if it’s the right choice for your project, and to start building. Distilling decades of experience, research, and best practices, it covers:
- Material specifications, performance, and when and where to use it
- Pros and cons of different fills from gravel, to earth and clay, to insulative perlite, rice hulls, and volcanic stone
- Illustrated, step-by-step guidance for efficient bag filling and installation
- Details for various designs, including domes and arches
- Foundation options and seismic and stability considerations
- Finishing and maintenance techniques
- Tools and materials
- Additional resources.
Essential Earthbag Construction presents the practical guidance and best practices for both the DIYer and professional to design and build high-quality earthbag structures.
“A comprehensive, practical and inspirational guide that is both detailed and easy to follow.” —Jenny Pickerill, Professor of Environmental Geography, University of Sheffield, UK and author of Eco-Homes: People, Place and Politics
“Everything you need to know for success.” —Michael G. Smith, co-editor, The Art of Natural Building and co-author, The Hand-Sculpted House
Product Details
| ISBN-13: | 9781771422512 |
|---|---|
| Publisher: | New Society Publishers |
| Publication date: | 07/14/2023 |
| Series: | Sustainable Building Essentials , #8 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 139 |
| File size: | 16 MB |
| Note: | This product may take a few minutes to download. |
| Age Range: | 16 - 18 Years |
About the Author
Kelly Hart is a pioneering earthbag builder, author, and filmmaker. Kelly's other publications include Rolling Shelter: Vehicles We Have Called Home, and Earthbag Architecture: Build Your Dream with Bags. Kelly lives in Silver City, New Mexico.
Read an Excerpt
Chapter 1: A Brief History of Earthbag Building
Bags of sand or dirt have been used to build military bunkers or divert flood waters for over a century. They are a good choice for this because they are easy to carry to where they are needed, can be quickly filled with local material, are inexpensive and are quite effective at protecting people and property. Of course these uses are generally just temporary. Using sandbags (or earthbags, as we refer to them here) for more permanent structures has only occurred in the last few decades.
In 1976 at the Research Laboratory for Experimental Building at Kassel Polytechnic College in Germany, Gernot Minke started experimenting with ways to make housing by using loose natural materials. He found that some materials could be placed into fabric tubes and that pumice showed particular promise because it is both lightweight and insulating. At first he built simple corbelled domes in an inverted catenary arch shape, using a rotating template to help place the tubes.
In 1978, Minke's team built a vertical walled house in Guatemala, using cotton tubes that were soaked in lime-wash as a preservative. Vertical bamboo poles were placed at intervals on both sides of the filled tubes and tied with wire between them to provide stability to the wall. The bamboo was also tied into the foundation and the top beam to provide an earthquake resistant structure.
In 1984 Iranian-born architect, Nader Khalili, proposed filling bags with moon dust as a way to build shelters on the moon. He refined this idea for building on Earth by placing strands of barbed wire between the courses of bags, thus unifying the shell into a more monolithic and shock resistant structure. Khalili evolved the sandbag idea into what he called "Superadobe" by filling polypropylene bags or long tubes with moistened adobe soil that would solidify when dry.
Khalili publicized his Superadobe concept widely through various media and began conducting workshops and seminars on the techniques that he had developed, mainly at his California Institute of Earth Architecture. Based on exposure to these ideas many other people started experimenting with their own building projects. Joe Kennedy, Paulina Wojziekowska, Kaki Hunter and Doni Kiffmeyer all initially studied with Khalili, and the more general term "earthbag" building became popular.
Paulina Wojciechowska wrote the first book on the topic of earthbag building: Building with Earth: A Guide to Flexible-Form Earthbag Construction, published in 2001. This was followed by the publication of Earthbag Building: the Tools, Tricks and Techniques by Kaki Hunter and Doni Kiffmeyer in 2004.
Akio Inoue has done extensive experimentation with earthbag dome construction, both on the campus of Tenri University where he taught in Japan and in India and Africa where many other domes were built for assistance programs.
Fig. 1.1 [Insert photo: fig11.jpg]
Caption: The author's earthbag dome home under construction.
Credit: Kelly Hart
Kelly Hart (the author of this book) first began experimenting with earthbag building in 1997, after producing his video program, A Sampler of Alternative Homes: Approaching Sustainable Architecture. He later documented his experience in actually building his own home in another program titled Building with Bags: How We Made Our Experimental Earthbag/Papercrete Home.
In 1999, Nader Khalili patented his "Superadobe" technique in the U.S., despite the fact that patent law clearly states that such a patent cannot be obtained if the concept were publicized for over a year prior to the patent application.
Besides filling the bags with adobe soil, many people have successfully tried filling the bags with a variety of other materials, such as crushed volcanic rock, crushed coral, non-adobe soils, gravel, and rice hulls.
Around 2009, Fernando Pacheco, a Brazilian engineer experimented with using open mesh bags or tubing, similar to the sort of material commonly used to package bulky produce. He called his technique "Hyperadobe" and suggested that it has many advantages, such as creating a more monolithic structure and eliminating the need for barbed wire and mesh for stabilizing plaster.
In the mid-1990's various engineering tests were performed on earthbag structures at Khalili's Institute, proving the efficacy of his techniques and enabling building department approval for some specific designs.
In 2006, at the request of Dr. Owen Geiger of the Geiger Research Institute of Sustainable Building, the Department of Civil and Mechanical Engineering of the U.S. Military Academy at West Point conducted several controlled and computer-monitored tests to determine the ability of polypropylene earthbags filled with sand, local soil, and rubble to withstand vertical loads. Their written report concluded that "overall, the earthbags show promise as a low cost building alternative. Very cheap, and easy to construct, they have proven durable under loads that will be seen in a single story residential home. More testing should prove the reliability and usefulness of earthbags."
Even with these tests and many others, earthbag building has yet to be incorporated into the International Residential Building Code. Hundreds of permanent and emergency earthbag dwellings have been built all around the world, some of them quite elegant. I wouldn't be surprised if many of these earthbag homes are still standing long after their conventional counterparts built contemporaneously have disintegrated.
As an example of the robust permanence of earthbag building, all of the more than fifty earthbag structures that existed in Nepal prior to their devastating earthquake in the spring of 2015 survived with only cosmetic damage. In some instances whole villages were flattened with the exception of the rare earthbag building. This has not escaped the attention of the international aid community and the Nepalese authorities, who are now recommending that communities rebuild with earthbags.
***
Chapter 2: Appropriate Uses for Earthbags
Earthbag construction is remarkably versatile, perhaps more than any other building technique. It can be employed both above and below ground without concern for rot or degradation. It can create a thermal mass or an insulating barrier, depending on what the bags are filled with. It can be fashioned into a wide range of building shapes, from organically curvy to completely rectilinear, from domes to boxes, or combinations of all of these. It can be extremely durable, resisting fire, flood, earthquake, tornado, bullets and time. It can be quite economical, literally dirt cheap. The techniques are simple to learn and can be done by unskilled labor for the most part. The building shells are generally non-toxic, using natural materials that can be returned to the earth or recycled at the end of their useful life. Often very little wood or industrial materials are needed, so the building is environmentally benign. A simple rubble trench foundation may be all that is required, eliminating the need for a massive concrete foundation. Besides buildings, earthbags can be used to build dams, cisterns, retaining walls, and other landscaping features. What more could you want?
Of course all of the above considerations depend on good design and execution in order to expect good results. It is best to become educated about proper design principles and procedures before embarking on any project. Hopefully this book will help you with this.
Earthbag walls are usually rather thick and heavy, so this limits some possible uses. For instance they may not be the best choice for interior walls where space may be limited, where it may be necessary to run plumbing, or where there may not be an adequate foundation to support the weight.
In most climates around the world it is best for the shell of a habitable building to be insulated from the extremes of ambient temperatures in order to have a comfortable and energy-efficient dwelling. Unfortunately, most soils are poor insulators, so filling earthbags with soil has limited utility. To remedy this it is possible to either fill the bags with a more insulating material or to add a secondary insulating layer on the outside of the shell. Lightweight volcanic stone (such as scoria or pumice), perlite, vermiculite and rice hulls are all insulating materials that could be used for fill. These materials are not available in all localities, or might be too expensive for any given project, so this should be a factor in deciding whether to build with earthbags.
Fig. 2.1 [Insert photo: fig21.jpg]
Caption: Looking straight up inside an earthbag dome shows the spiraling pattern of bags closing in to cap the dome. This was a small, mostly underground dome with earthen fill situated in the desert southwestern United States.
Credit: Kelly Hart
While a wide range of building shapes are possible with earthbags there are some design limitations. In general, vertical walls are quite stable when curved, but may require additional buttressing support when they are straight. Earthbags make great domes, but should be no larger than about 20 feet (6 m) in diameter and cannot be hemispherical; catenary arches are the best dome shape to emulate. Domes need to be circular at the base so that all of the forces around them are equally balanced; otherwise there is the risk of deformation and failure. Furthermore, earthbag domes are best limited to fairly arid climates, as it is difficult to assure that the final plaster will always be water tight in wetter climates. Vaults, except for very narrow ones (less than 8 feet or 2.5 m wide) that are well buttressed, should be avoided; they are simply too unstable. Walls that have many openings for doors and windows are probably best framed with wood because there are limits to how many such openings can be placed in an earthbag wall.
Most earthbag buildings are just one story high or at most only high enough to accommodate a small loft area. It is possible to build multi-story earthbag buildings, but they need to be carefully engineered to assure safety. I would think that a basement with two additional stories above it would be the limit for any earthbag building.
Remodeling an earthbag building can present some challenges, especially in terms of cutting through existing earthbag walls for new doors or windows. If one anticipates the need to eventually remodel or add more space to an earthbag building, the best way to accommodate this is to create the opening at the time of original construction and simply fill it in with temporary earthbags so that when the time comes to cut through it is easy to just knock out the dummy bags.
Hanging heavy things on earthbag walls can present problems. It is best to anticipate this during the construction phase by incorporating provisions for attaching things in those places where this might occur. It is possible to do this later, but it might be awkward or inconvenient to do so.
A general problem with earthbag building is that you may have to jump through some extra hoops to obtain a building permit if this is required. Earthbag technology is simply too new and too alternative to have generated the necessary impetus for uniform codes to have been adopted. This means that in order to be acceptable to the authorities, any given plan may need to be signed by a licensed engineer or architect to vouch for its safety, and this can add to the time and expense of the project.
***
Chapter 7: Building Walls
Once you have established your foundation you can begin to create the earthbag walls. No matter what the fill material will be, the process of laying the bag wall is similar. The main difference is whether you will be using individual bags or sections of the long tubing, and I'll address these differences below.
Locate source of fill material
The first order of business is to source the basic fill material and have it stationed as near to the foundation as is practical. In some cases this might be a nearby pit or even an area inside the foundation where soil needs to be excavated. I have known of projects where soil was removed from a hole that eventually became a pond or underground cistern associated with the house.
If you are mixing materials to provide the appropriate fill, then you need to arrange some way to actually do the mixing. This might best be done in advance of filling the bags, or it might be done just prior to filling, possibly by another person, depending on the logistics of the process. Mixing can be done manually with shovels or with mechanized mixers such as cement mixers, backhoes or front end loaders.
Fig. 7.1 Insert photo: fig71.jpg
Caption: The fill soil for this dome project was brought to the site by dump truck and placed near where the work was being done.
Credit: Kelly Hart
If the fill material is soil, or stabilized soil, then it should be dampened enough to be able to tamp it into a solid block. This should be just damp enough that moisture does not ooze from the bags when they are tamped; you don't want mud.
Filling bags
To fill individual bags it greatly helps to have a chute or funnel of some sort that will just fit into the bags to facilitate this process. Either this or some kind of special stand that will hold the bag up and open to receive the fill will do. Both of these are described in the chapter on tools.
You can use a shovel to fill the bags directly or a small bucket that can be carried with fill material and dumped into the bag. The bucket approach becomes much more desirable as the wall gets higher and you want to fill the bags in place on the wall. A wheel barrow might be useful to have fill material adjacent to where the bags are being filled.
Fig. 7.2 Insert photo: fig72.jpg
Caption: The bags on this dome are being filled in place with buckets of soil. You can see how the bag is placed on a metal slider in such a way that it can be laid down against the previously placed bag.
Credit: Kelly Hart
I much prefer to fill the bags right where they will be placed on the wall. Unless you are a football player who enjoys carrying 100 pound sacks of soil and hoisting them onto a wall, it is easier to fill the bags incrementally in place, and this will likely save a lot of back strain. If you have helpers one person (or even a bucket brigade) can carry the fill to where it is needed while another person makes sure that the right amount of fill goes into the bag and lays the bag down into place when it is ready.
When the fill material is light weight, like volcanic stone or perlite, then it might make more sense to completely fill the bags on the ground and then carry them to the wall being built. When I built a sizable earthbag dome house using scoria as fill, I could easily carry full bags up a ladder and place them on the wall because they only weighed about 35 lbs apiece. My wife was able to help by filling up a bunch of bags and leaving them near the pile of scoria for me to carry.
Fig. 7.3 Insert photo: fig73.jpg
Caption: A short section of mesh tubing is being fitted over a chute made from cutting the bottom out of a bucket, so that it can then be placed on the wall behind.
Credit: Kelly Hart
When you are laying the long tubing there is really no choice but to fill the tubes directly where they should go on the wall; you can't effectively carry a long tube that has been filled in advance. The process of laying tubing involves first measuring how long the piece of tubing should be to complete a section of wall and adding enough extra length to be ble to close or seal each end. The end that will first be laid down can be permanently tied in a knot or hemmed with wire stitching or staples. The open end is then slipped over some kind of filling tube or chute that will allow most of the length of tubing to be scrunched up onto it.
The closed end is placed exactly where you want that row to start, while the fill material is poured by buckets or otherwise conveyed into the chute and allowed to settle all the way to the end of the bag. This process is best done by several people, with one person holding the chute and keeping it stable (sometimes with a leg that helps support the tubing at an angle as the fill descends) and at least one other person pouring in the fill material. A bucket brigade can make this process rather continuous. As the tubing at the base gets full of material the person coordinating the chute position will be stepping backwards to allow it to fall into place on the wall. It might help to have another person whose job is to precisely keep the tubing exactly where it should go so that another person can come behind with a tamper and do the final tamping. As you can imagine, a well-coordinated team could very quickly lay down a section of wall in this manner.
***
Laying bags in a pattern
One of the basic principles of laying individual bags is to arrange each bag relative to the others in the wall as if it were a brick in a brick wall with a "running bond" pattern. This means that bags are always placed over the space between the two bags beneath it. The more precisely you can adhere to this rule, the stronger the wall will be. To do this often requires smaller, half bags to be prepared to initiate or continue the pattern.
Fig. 7.5 Insert photo: fig75.jpg
Caption: The running bond pattern of this earthbag wall is obvious by the diagonal shapes made by the end of each bag. You can also see how the bottoms of the bags are exposed where the wall ends.
Credit: Kelly Hart
Another rule is that you never place a loose end exposed at an opening or at a corner where it might be vulnerable to spilling any of the contents. The sewn base of individual bags is much more secure in this situation, so when you start laying bags at a corner or an opening, always put the base outward and lay the bag down with the open end falling in the direction that course will proceed. The next bag laid down can be reversed so that the two open ends meet and will be tamped together to seal them.
Table of Contents
Acknowledgments
Foreword
Chapter 1: A Brief History of Earthbag Building
Chapter 2: Appropriate Uses for Earthbags
Chapter 3: Building Science Notes
Chapter 4: Material Specifications
Bags
Fill materia
Barbed wire and other types of reinforcement
Plaster
Chapter 5: Tools
Chapter 6: Foundations
Chapter 7: Building Walls
Locate source of fill material
Filling bags
Placing barbed wire and twine
Laying bags in a pattern
Closing the top of the bag
Using a metal slider
Tamping the bags
Placing vertical reinforcement rods
Building domes
Chapter 8: Design Considerations and Constraints
Vertical walls
Domes
Vaults
Buttresses
Bond beams
Door and window openings
Door and window bucks
Arches and other shapes
Spacing openings
Vertical reinforcement for openings
Lintels
Wall thickness
More than one story
Below-grade construction
Chapter 9: Plastering the Walls
Chapter 10: Floor and Roof Options
Slab on grade
Masonry floors
Adobe floors
Suspended floors
Roofs
Chapter 11: How to Include Utilities
Plumbing
Electrical
Heating
Ventilation
Cabinetry
Chapter 12: Strategies for Seismic Reinforcement
Chapter 13: General Budgeting Information
Chapter 14: Maintenance and Renovation
Chapter 15: Building Codes
Chapter 16: Other Uses for Earthbags
Retaining walls
Cisterns
Dams
Root cellars and pantries
Sculpture and art
Resources
Author's websites
Other websites
Books
DVDs
Workshops
Bag supplies online
Index
About the Author
A Note About the Publisher
What People are Saying About This
"A must-have book for anyone interested in natural and sustainable building. It expands the possibilities with practical and essential information on this user-friendly method of construction."
— Will Beemer, Director of the Heartwood School for the Homebuilding Crafts and author of Learn to Timber Frame.
"Kelly Hart and Dr. Owen Geiger (who wrote the very informative Foreword) probably know as much about earthbag building as anyone. Friend Kelly has always had a clear and concise way of explaining his subject, both in lectures and in his several books. I've never built an earthbag structure, although we once did a cordwood building on an earthbag foundation in New Zealand. But I wouldn't even attempt it without studying this book thoroughly and referring to it throughout the building process."
— Rob Roy, Director, Earthwood Building School and author of Essential Cordwood Building
"There is an urgent need for more sustainable homes and earthbag construction offers excellent, affordable, strong eco-friendly housing using natural and local materials. They are beautiful, comfortable and robust. This book is a comprehensive, practical and inspirational guide that is both detailed and easy to follow. Hart demonstrates that anyone can build a home, so use this book and give it a go."
— Jenny Pickerill, Professor of Environmental Geography, Universityof Sheffield, UK and author of Eco-Homes: People, Place and Politics (Zed Books)
"Who doesn't love earthbags? Only people who don't know about this most versatile of earthen building techniques, suitable for building inexpensive low-impact homes on most parts of the globe. With just a pile of dirt, some bags, barbed wire, a tamper and a few basic tools, you can build an earthbag dome, retaining wall, or root cellar. For over 20 years author Kelly Hart has been experimenting and promoting simple DIY ecological building techniques, especially via his excellent web sites. Distilling both his own hard-won experience and the combined wisdom of the rapidly-expanding worldwide earthbag network, Hart delivers a thorough, detailed and readable guidebook that tells you everything you need to know for success with this potent technique."
— Michael G. Smith, co-editor, The Art of Natural Building and co-author, The Hand-Sculpted House