Interámerica's Adobe Builder: Earthbuilder's encyclopedia - CD resources for adobe, rammed earth, pressed block, solar design and green. The Earthbuilder's Encyclopedia. Joseph M. Tibbits. Southwest Solar Adobe School, Bosque, NM. Adobe Fireplaces. Adobe Remodeling. Myrtle Stedman. The Earthbuilders Encyclopedia has blueprints for a fireplace and lots of tips for adobe brick fireplaces that can be easily adapted to cob. See the recommended .
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Earthbuilders Encyclopedia: The Master Alphabetical Reference for Adobe and Rammed Earth [Joe Tibbets] on quollevcomeedart.cf *FREE* shipping on qualifying. Ch"pte I. INTRODUCTION. Probably one of the first homes man lived in after he came out of a cave. wat made of eatth. To he sure, the earliest known kinds of. Download as PDF, TXT or read online from Scribd. Flag for Tibbets, Joseph M. The Earthbuilders Encyclopedia. Bosque Building with Rammed quollevcomeedart.cf
We practice a particular brand of earthbag building that prioritizes ease of construction coupled with structural integrity inspired by FQSS principles. What is FQSS? We made a list of what fosters a productive yet playful work environment. The process has to be Fun. What helps make the job fun is that it flows Quickly, as long as we keep it Simple, and the results are Solid. When the work becomes in any way awkward or sloppy, FQSS deteriorates into fqss: frustrating, quarrelsome, slow, and stupid.
This prompts us to re-evaluate our tactics, or blow the whole thing off and have lunch. Returning refreshed often restores FQSS approval spontaneously.
By demonstrating guidelines that effectively enhance the quality of earthbag construction, we hope to encourage a standard that aids the mainstream acceptance of this unique contemporary form of earthen architecture.
Throughout this work we often use synonymous terms to describe the same thing. For example, we intermix the use of the words earth, soil, dirt, and fill. They are all used to describe the magical mix of naturally occurring sand and clay, sometimes with the addition of fiber, and almost always in conjunction with some amount of water.
Our intent is to inform, educate, and inspire earthbag construction in playful layman terms using written text and step-by-step, how-to illustrations. The focus of this book is on sharing our repertoire of tools, tricks, and techniques that we have learned through trial and error, from friends, workshop participants, curious onlookers, ancient Indian nature spirits, and smartass apprentices who have all helped us turn a bag of dirt into a precision wallbuilding system that alerts the novice and experienced builder alike to the creative potential within themselves and the very earth beneath their feet.
This is the premise that inspired the imagination of international visionary architect Nader Khalili when he conceived the idea of Sandbag Architecture.
In his quest to seek solutions to social dilemmas like affordable housing and environmental degradation, Nader drew on his skills as a contemporary architect while exercising the ingenuity of his native cultural heritage. Monolithic earthen architecture is common in his native home of Iran and throughout the Middle East, Africa, Asia, Europe, and the Mediterranean.
Thousands of years ago, people discovered and utilized the principles of arch and dome construction. By applying this ancient structural technology, combined with a few modern day materials, Nader has cultivated a dynamic contemporary form of earthen architecture that we simply call Earthbag Building. Simplicity Earthbag Building utilizes the ancient technique of rammed earth in conjunction with woven bags and tubes as a flexible form.
The basic procedure is simple. The bags or tubes are filled on the wall using a suitable pre-moistened earth laid in a mason style running bond. After a row has been laid, it is thoroughly compacted with hand tampers. This provides exceptional tensile strength while allowing the rows to be stepped in to create corbelled domes and other unusual shapes Fig.
Walls can be linear, free form, or a perfect circle guided by the use of an architectural compass. Arched windows and doorways are built around temporary arch forms until the keystone bags are tamped in place.
The finished walls then cure to durable cement-like hardness. Simple, low cost foundations consist of a rubble trench system, or beginning the bag-work below ground with a cement-stabilized rammed earth mix for the stem walls. Many other types of foundation systems can be adapted to the climatic location and function of the structure.
Earthbag construction enables the design of monolithic architecture using natural earth as the primary structural element.
By monolithic architecture we mean that an entire structure can be built from foundation and walls to roof using the same materials and methods throughout.
Corbelled earthbag domes foster the ultimate experience in sculptural monolithic design, simplicity, beauty, and dirt-cheap thrills. Earthbag domes designed with arch openings can eliminate 95 percent of the lumber currently used to build the average stick frame house Fig.
Conventional wood roof systems still eat up a lot of trees. Why cut and haul lumber from the Northwest to suburban Southern California, Tucson, or Florida when the most abundant, versatile, energy efficient, cost effective, termite, rot and fire proof construction material is available right beneath our feet?
Even alternative wall systems designed to limit their use of wood can still swallow up as much as 50 percent of that lumber in the roof alone. Earth is currently and has been the most used building material for thousands of years worldwide, and we have yet to run out.
We love earthen construction in all its forms. Nothing compares with the beauty of an adobe structure or the solidity of a rammed earth wall. The sheer joy of mixing and plopping cob into a sculptural masterpiece is unequalled. Adobe is one of the oldest known forms of earthen building. It is probably one of the best examples of the durability and longevity of earthen construction Fig 1.
Adobe buildings are still in use on every continent of this planet. It is particularly evident in the arid and semi-arid areas of the world, but is also found in some of the wettest places as well.
In Costa Rica, C. Adobe is made using a clay-rich mixture with enough sand within the mix to provide compressive strength and reduce cracking.
The mix is liquid enough to be poured into forms where it is left briefly until firm enough to be removed from the forms to dry in the sun. The weather must be dry for a long enough time to accomplish this. The adobes also must be turned frequently to aid their drying Fig.
SWSA 1. They cannot be used for wall building until they have completely cured. While this is probably the least expensive form of earthen building, it takes much more time and effort until the adobes can be effectively used. Adobe is the choice for dirt-cheap construction. They can be hand-patted into the desired shape and left to dry until ready to be mortared into place. Earthbags, on the other hand, do not require as much time and attention as adobe.
Since the bags act as a form, the mix is put directly into them right in place on the wall. Not as much moisture is necessary for earthbags as adobe. This is a distinct advantage where water is precious and scant.
Earthbags cure in place on the wall, eliminating the down time spent waiting for the individual units to dry. Less time is spent handling the individual units, which allows more time for building. Even in the rain, work on an earthbag wall can continue without adversely affecting the outcome. Depending on the size, adobe can weigh as much as pounds Between turning, moving, and lifting into place on the wall, each adobe is handled at least three or four times before it is ever in place.
Adobe is usually a specific ratio of clay to sand. Steel whalers keep forms true and plumb and resist ramming pressure.
Rammed earth is another form of earth building that has been around for centuries and is used worldwide. Many kilometers of the Great Wall of China were made using rammed earth.
Multi-storied office and apartment buildings in several European countries have been built using rammed earth, many of them in existence since the early s. Rammed earth is currently enjoying a comeback in some of the industrialized nations such as Australia.
Rammed earth involves the construction of temporary forms that the earth is compacted into. These forms must be built strong enough to resist the pressure exerted on them from ramming compacting the earth into them.
Traditionally, these forms are constructed of sections of lashed poles moved along the wall after it is compacted. Contemporary forms are complex and often require heavy equipment or extra labor to install, disassemble, and move Fig. The soil is also of a specific ratio of clay to sand with about ten percent moisture by weight added to the mix. In most modern rammed earth construction, a percentage of cement or asphalt emulsion is added to the earthen mix to help stabilize it, increase cohesion and compressive strength, and decrease the chance of erosion once the rammed earth wall is exposed.
While the optimum soil mix for both rammed earth and earthbag is similar, and both types of construction utilize compaction as the means of obtaining strength and durability, that is about where the similarity ends.
Since the forms are generally constructed of wood and steel, they tend to be rectilinear in nature, not allowing for the sweeping curves and bends that earthbag construction can readily yield, giving many more options to an earth builder Fig. WANEK rammed earth is thought of as an optimum, earthbags permit a wider range of soil types.
And just try making a dome using the rammed earth technique, something that earthbags excel at achieving. Cob is a traditional English term for a style of earth building comprised of clay, sand, and copious amounts of long straw. Everybody loves cob. It is particularly useful in wetter climates where the drying of adobes is difficult. England and Wales have some of the best examples of cob structures that have been in use for nearly five centuries Fig.
Cob is also enjoying a resurgence in popularity in alternative architecture circles. They have produced some very fine written material on the subject and offer many workshops nationwide on this type of construction. Consult the resource guide at the back of this book to find sources for more information on cob. Like earthbag, cob can be formed into curvilinear shapes due to its malleability.
Unlike earthbag, cob requires the use of straw, lots of straw. The straw works for cob the same way that steel reinforcing does for concrete.
As a cob wall grows in height, the weight of the overlying cobs can begin to deform the lower courses of cob if they are still wet. The amount of time necessary is dependent on the moisture content 1. Earthbag building doesn't require any of this extra attention due to the nature of the bags themselves. So the main advantages of earthbag over cob are: no straw needed, no waiting for a lift to set up, wider moisture parameters, and a less specific soil mix necessary.
Pressed block is a relatively recent type of earthen construction, especially when compared to the above forms of earth building. It is essentially the marriage of adobe and rammed earth. Using an optimum rammed earth mix of clay and sand, the moistened soil is compressed into a brick shape by a machine that can be either manual or automated.
A common one used in many disadvantaged locales and encouraged by Habitat for Humanity is a manual pressed-block machine. Many Third World communities have been lifted out of oppressive poverty and homelessness through the introduction of this innovative device Fig 1.
The main advantage of earthbag over pressed block is the same as that over all the above-mentioned earth-building forms, the fact that earthbags do not require a specific soil mixture to work properly. Adobe, rammed earth, cob, and pressed block rely on a prescribed ratio of clay and sand, or clay, sand, and straw whose availability limits their use. The earthbag system can extend earthen architecture beyond these limitations by using a wider range of soils and, 1.
Other Observations Concerning Earthbags Tensile strength. Another advantage of earthbags is the tensile strength inherent in the woven poly tubing combined with the use of 4-point barbed wire. Rammed earth and even concrete need the addition of reinforcing rods to give them the strength necessary to keep from pulling apart when placed under opposing stresses. The combination of textile casing and barbed wire builds tensile strength into every row of an earthbag structure. Flood Control.
Earthbag architecture is not meant to be a substitute for other forms of earth building; it merely expands our options. One historic use of earthbags is in the control of devastating floods. Not only do sandbags hold back unruly floodwaters, they actually increase in strength after submersion in water. We had this lesson driven home to us when a flash flood raged through our hometown.
By the next morning, the water had percolated through our porous, unfinished earthen floor leaving a nice layer of thick, red mud as the only evidence of its presence.
Other than dissolving some of the earth plaster from the walls at floor level, no damage was done. In fact, the bags that had been submerged eventually dried harder than they had been before. And the mud left behind looked great smeared on the walls! Built-in Stabilizer. The textile form bag!
In order to stabilize the soil in some forms of earth construction, a percentage of cement, or lime, or asphalt emulsion is added that chemically alters the composition of the earth making it resistant to water absorption.
Earthbags, on the other hand, can utilize raw earth for the majority of the walls, even below ground, thanks to this mechanical stabilization. This translates to a wider range of soil options that extends earth construction into nontraditional earth building regions like the Bahamas, South Pacific, and a good portion of North America.
While forests are dependent on specific climatic conditions to grow trees, some form of raw earth exists almost everywhere. The Proof is in the Pudding Nader Khalili has demonstrated the structural integrity of his non-stabilized natural raw earth earthbag domes.
Under static load testing conditions simulating seismic, wind, and snow loads, the tests exceeded Uniform Building Code requirements by percent. No surface deflections were observed, and the simulated live load testing, done at a later date, continued beyond the agreed limits until the testing apparatus began to fail. The buildings could apparently withstand more abuse than the equipment designed to test it! The earthbag system has been proven to withstand the ravages of fire, flooding, hurricanes, termites, and two natural earthquakes measuring over six and seven on the Richter scale.
The earthbag system in conjunction with the design of monolithic shapes is the key to its structural integrity. Thermal Performance Every material in a building has an insulation value that can be described as an R-value. Most builders think of R-value as a description of the ability of a structure or material to resist heat loss. This is a steady state value that doesn't change regardless of the outside temperature variations that occur naturally on a daily and annual basis.
So why does an earthbag structure or any massive earthen building for that matter with an R-value less than 0. From this simple formula we can see that material with a high R-value will yield a low U-value.
U-value units of thermal radiation measures a material's ability to store and transfer heat, rather than resist its loss. Earthen walls function as an absorbent mass that is able to store warmth and re-radiate it back into the living space as the mass cools.
This means that at the hottest time of the day the inside of an earthbag structure is at its coolest, while at the coolest time of the day the interior is at its warmest. Of course this thermal performance is regulated by many factors including the placement and condition of windows and doors, climatic zone, wall color, wall orientation, and particularly wall thickness. This twelve-hour delay is only possible in walls greater than 12 inches 30 cm thick.
An earthen structure offers a level of comfort expressed by a long history of worldwide experience. Properly designed earthbag architecture encourages buried architecture, as it is sturdy, rot resistant, and resource convenient.
Bermed and buried structures provide assisted protection from the elements. Berming this structure in a dry Arizona desert will keep it cool in the summer, while nestling it into a south-facing hillside with additional insulation will help keep it warm in a Vermont winter. The earth itself is nature's most reliable temperature regulator. Cost Effectiveness Materials for earthbag construction are in most cases inexpensive, abundant, and accessible. Grain bags and barbed wire are available throughout most of the world or can be imported for a fraction of the cost of cement, steel, and lumber.
Dirt can be harvested on site or often hauled in for the cost of trucking. When we switched to earthen dome construction, we kissed our lumberyard bills goodbye. What one saves on materials supports people rather than corporations. Properly designed corbelled earthbag domes excel in structural resilience in the face of the most challenging of natural disasters.
Does it really make sense to replace a tornado-ravaged tract house in Kansas with another tract house? An earthbag dome provides more security than most homeowner insurance policies could offer by building a house that is resistant to fire, rot, termites, earthquakes, hurricanes, and flood conditions. Sustainability Earthen architecture endures.
That which endures sustains. Examples of early Pueblo earthen construction practices dating from AD is evident throughout the Southwestern United States Fig 1. In the rainy climate of Wales, the thick earthen cobwalled cottages protected under their thatched reed roofs boast some to hundred years of continual use. If we can build one ecologically friendly house in our lifetime that is habitable for years, we will have contributed towards a sustainable society. We strive for an optimal, rammed earth-soil ratio of approximately 30 percent clay to 70 percent sand.
According to David Easton, in The Rammed Earth House see Resource Guide , most of the world's oldest surviving rammed earth walls were constructed of this soil mix ratio. We like to use as close a ratio mix to this as possible for our own projects. This assigns the use of the bags as a temporary form until the rammed earth cures, rather than having to rely on the integrity of the bag itself to hold the earth in place over the lifetime of the wall. However, the earthbag system offers a wide range of successful exceptions to the ideal soil ratio, as we shall discover as we go on.
T The Basic Components of Earth Building Soil Clay plays the leading role in the performance of any traditional earthen wall building mix. It is produced by the chemical decomposition of rock 2. Clay is to a natural earthen wall what Portland cement is to concrete. Clay has an active, dynamic quality.
When wet, clay is both sticky and slippery, and when dry, can be mistaken for fractured rock Fig. Sands and gravels, on the other hand, remain stable whether wet or dry.
One of the magical characteristics of clay is that it possesses a magnetic attraction that makes other ingredients want to stick to it. A good quality clay can be considered magnetically supercharged. Think of the times a wet, sticky mud has clung tenaciously to your shoes or the fenders of your car. Another of clay's magical traits can be seen under a microscope. On the microscopic level, clay particles resemble miniscule shingles that, when manipulated by a tamper in our case , align themselves like fish scales that slip easily in between and around the coarser sand and gravel particles.
This helps to tighten the fit within the matrix of the earth building soil, resembling a mini rock masonry wall on a microscopic level. Not all clays are created alike, however. Clays vary in personality traits, some of which are more suitable for building than others.
The best clays for wall building and earth plasters are of a relatively stable character. They swell minimally when wet and shrink minimally when dry. Good building clay will expand maybe one-half of its dry volume. Very expansive clays, like bentonite and montmorillonite, can swell times their dry volume when wet.
Typical clays that are appropriate for wall building are lateritic in nature containing concentrations of iron oxides and iron hydroxides and kaolinite. Expansive clay, like bentonite, is reserved for lining ponds and the buried faces of retaining walls or for sealing the first layer on a living roof or a buried dome.
Fortunately, it is not necessary to know the technical names of the various clays in order to build a wall. You can get a good feel for the quality of a clay simply by wetting it and playing with it in your hands. A suitable clay will feel tacky and want to stick to your skin. Highly expansive clay often has a slimy, almost gelatinous feel rather than feeling smooth yet sticky. In the southwestern United States, there are several experienced builders and contractors, and rammed earth is starting to appear in building codes in that area.
Earthbag Building - The Tools, Tricks and Techniques
Outside of the Southwest, it's generally not mentioned and will require more research and persistence on the part of the person trying to get a construction loan, a mortgage or home insurance. Earthbag homes are another way to build a home out of the earth. In this case, bags are filled with dirt and stacked like bricks.
Earthbag construction is generally easier for a first-time builder to do without the help of a crew, which might cut down on construction costs. In earthbag building, the bags provide the form for the earth and are a little more user friendly than the wooden forms that you use for rammed earth homes. Rammed earth also requires a more specific mix of dirt and clay than the soils that go into earthbags, so it's easier to use on-site soil in earthbag building.
However, because earthbag homes are usually built into small domes, there's more structural freedom with rammed earth homes. Shake it up; let it sit overnight or until clear. The coarse sands will sink to the bottom, then the smaller sands and finally the silt and clay will settle on top.
You want to see distinctive layers. This will show the approximate ratios. To give a rough estimate, a fine top layer of about one-third to one-quarter the thickness of the entire contents can be considered a suitable soil mix.
Materials and workmanship for earth buildings
Three sample soils and their appropriate uses. In some cases the choice of an earth building soil mix may depend on the climate. After a wall is built and standing for a few seasons some interesting observations can be made. Earthbag walls made with sandy soils are the most stable when they get wet. The richer a soil is in clay, the more it will shrink and expand in severe weather conditions.
Dry climates can take advantage of earthen and lime plasters over a broad variety of soil mixes as there is less chance of walls being affected by expansion and contraction. Soils of varying ratios of clay and sand have unique qualities that can often be capitalized on just by designating them different roles.
A soil sample with a high clay content may be reserved for an earthen plaster amended with straw. Once we know our soil ratios from the jar test, we can go ahead and make a sample bag to observe the behavior of the soil as it dries and test its strength when cured.
Seeing and feeling help us determine if we want to amend the soil with another soil higher in whatever may be lacking in this one, or give us the confidence that this soil is bombproof the way it is.
If the soil is hopelessly inadequate for structural purposes, have no fear. Even the flimsiest of soils can still be used as non-load-bearing wall infill between a structural supporting post and beam system refer to Chapter 5. Gravel Yards: Imported Soil. A convenient and common source for optimum to adequate building soil is often obtained at more developed gravel yards.
Reject sand is often the largest pile at the gravel yard and is usually priced dirt cheap. The primary expense is in delivery. Pay a visit to your local gravel yard before ordering a truckload. Take some buckets to collect soil samples in to bring home for making sample tests. You may find unexpected sources of soil that are suitable for your needs.
This has largely been our experience when perusing gravel yards. Since a square foot 58 square meters structure can easily swallow up tons metric tonnes of material, it is our preference to pay the extra cost of importing this clean, uniform, easy to dig FQSS! However, the beauty of earthbag building allows us the freedom to expand our soil options by using most types of soil available on site.
All that was available to them was a mixture of coarse, crushed coral and sand so fine it bled the color and consistency of milk when wet.
This material was obtained from the commercial dredging of a nearby marina. Because of the coarseness and size variety within the matrix of the fill material, it packed into a very solid block in spite of a clay content of zero percent Fig 2. The sharp coarseness of this decomposed granite fit like a jigsaw puzzle when tamped, locking all the grains together.
Marlene Wulf hand dug into a clay-rich slope of lateritic soil to build a bermed earthbag yurt in Georgia. Yet this coarse sandy mix has proven to endure shear and load bearing tests that have exceeded Uniform Building Code UBC standards by percent. Smooth surface sands from sandstone are generally considered weak soils for wall building. Occasionally a situation arises where this kind of sand is our only option.
Here's where the built-in flexible form allows us the opportunity to greatly expand our options from the ideal soil ratio. This is when, yes, we do rely on the integrity of the bag to a certain extent to stabilize the earth inside.
In this case, we may consider building an above ground post and beam infill, or a partially-buried round kiva style structure to support the brunt of the wall system we would not consider building a dome with this weaker soil. Soil Preparation and Moisture Content Water plays a significant role in the preparation of the soil that will become the building blocks of our structure. Although we coined the phrase flexible-form 2.
Before making a sample bag, we need to determine the ideal moisture content for the particular soil we are working with. All soils are unique and behave differently from each other.
Each soil also behaves differently when prepared with differing amounts of water. This percentage of moisture in an average suitable building soil feels fairly dry.
It is damp enough to squeeze into a ball with your hand and hold together without showing any cracks Fig. A simple test is to moisten the soil and let it percolate evenly throughout the soil sample.
Squeeze a sample of the earth in your hand. Next, hold the ball out at shoulder height and let it drop to the ground. If it shatters, that approximates what 10 percent moisture content feels and looks like. There should be enough moisture that the soil compacts into a ball. This has long been considered the optimum moisture content for achieving thoroughly compacted rammed earth walls and compressed bricks.
Ten percent moisture content allows a typical rammed earth soil mix to be pounded into a rock hard matrix and is hence considered the optimum moisture content. We too have followed the optimal moisture content practice in most of our projects. We found these test results fascinating for a couple of significant reasons. We can take a soil sample of an average quality earth mix of 17 percent clay, 15 percent silt, and 68 percent sand and gravel, and add about ten percent more water than the traditional ten percent moisture content prescribed for a rammed earth mix.
The result produces a stronger yet less compacted finished block of earth. Rammed earth is produced with low moisture and high compaction. Harder equals stronger, etc.
What Minke is showing us is that the same soil with almost twice the ideal moisture content placed into a form and jiggled or in the earthbag fashion, tamped from above with a hand tamper , produces a finished block with a higher compression strength than that of a ten percent moisture content rammed earth equivalent.
What Minke is concluding is that the so-called optimum water content does not necessarily lead to the maximum compressive strength. On the contrary, the workability and binding force are the decisive parameters.
His theory is that the extra moisture aids in activating the electromagnetic charge in the clay. This, accompanied by the vibrations from tamping, causes the clay platelets to settle into a denser, more structured pattern leading to increased binding power and, ultimately, increased compression strength. What this means to us is less pounding FQSS! Our personal discoveries were made through trial and error and dumb luck. Weeper bag or bladder bag are dirtbag terms we use when the soil is what we used to consider too moist, and excess moisture would weep through the woven strands of fabric when tamped.
The extra moisture in the soil would resist compaction. Instead of pounding the bag down hard and flat, the tamper kind of bounced rather than smacked.
The weeper bag would dry exceedingly hard, although thicker than its drier rammed earth neighbor, as if it hadn't been compacted as much. We once left a five-gallon It became as saturated as an adobe mix. We mixed it up and let it sit in the bucket until dry, and then dumped it out as a large consolidated block. It sat outside for two years, enduring storms and regular yard watering, and exhibited only the slightest bit of erosion.
We have witnessed the same soil in a neglected earthbag made to the optimum 10 percent moisture specification and pounded mercilessly , dissolve into the driveway in far less time. So now we consider the weeper bag as not such a sad sight to behold after all. Our conclusion is that adapting the water content to suit the character of each soil mix is a decisive factor for preparing the soil for building. We are looking for a moisture content that will make the soil feel malleable and plastic without being gushy or soggy.
The ball test can still apply as before, only now we are looking for a moisture content that will form a ball in our hands when we squeeze it; but when dropped from shoulder height, retains its shape, showing cracking and some deformation, rather than shattering into smithereens Fig. Adjust the Moisture to Suit the Job Personal preference also plays a role in deciding one's ideal mix. A drier mix produces a firmer wall to work on. Each row tamps down as firm as a sidewalk.
Need we say a frozen pile of dirt would be difficult to work with? Earthbag walls need frost-free weather to cure properly. Once cured and protected from moisture invasion, earthbags are unaffected by freezing conditions. The samples left to right show moisture contents varying from 10 to 20 percent.
If you have a big crew capable of constructing several feet of wall height in a day, a drier mix will be desirable. The moister the mix the more squishy the wall will feel until the earth sets up some. With a smaller crew completing two or so rows of bag work a day, a moister mix will make their job of tamping easier. You will have to be the judge of what feels best overall and meets the needs of your particular circumstances.
Prepping soil Fig. Some soils need time to percolate in order for the water to distribute evenly throughout the pile. High clay soils require repeated watering to soften clumps as well as ample time to absorb and distribute the water evenly sometimes days.
Sandy soils percolate more quickly. They will need to be frequently refreshed with regular sprinklings Fig. Make some sample test bags. When making test bags, try varying the percentage of water starting with the famous ten percent standard as a minimum reference point. For some soils ten percent may still be the best choice.
For now, lets pre-moisten our test pile of dirt to about ten percent moisture. Once the proper moisture content has been achieved plan on a full day to a few days for this , fill some sample bags refer to Chapter 3 for details on the art of diddling and locking diddles for making the most of your test bag.
After filling, fold each bag shut and pin it closed with a nail. Lay the bags on the ground and tamp them thoroughly with a full pounder see Chapter 3 for description of pounders and other tools. Let them cure for a week or more in warm, dry weather, protected from frost and rain. Thick rammed earth walls can take months to fully cure, but after a week or two in hot, dry weather, our test bags should feel nice and hard when thumped.
Vary the moisture content in these test bags to get better acquainted with how they differ in texture while filling, how they differ while being tamped, and what the final dried results are. After the bags are sufficiently cured, we test each one by kicking it, like a tire. We jump up and down on it and drive three-inch 7. If the soil is hard enough to hold nails and resist fracturing, it is usually a pretty good soil.
If the soil is soft or shrunken, it will need to be avoided or amended or used as infill for a post and beam structure. We do these tests to determine which moisture ratio is best suited for this particular soil for more scientific code-sanctioned tests concerning modulus of rupture and compression, we suggest consulting the New Mexico Uniform Building Code Fig. Our personal feeling is that earthbag construction should be tested as a dynamic system rather than an individual unit.
The reason is shown in the next picture. Earth is a simple yet complex substance that you can work with intuitively as its merits become familiar.
Experimentation is a big part of the earthen construction game. Once the test bags have dried, and the right soil mix and the suitable moisture content for the particular job has been chosen, the building crew is ready to go to work. A team of six to eight people can go through about 25 tons Kept pre-moistened and protected with a tarp, it's ready for wall building throughout the week.
If the building process is simple, the progress is quick. Bags and Tubes: The Flexible Form The bags we use are the same kind of bags used most typically to package feed and grain Fig. The type and sizes we use most often are woven polypropylene pound and pound misprints with a minimum ten-by-ten denier weave per square inch. The companies that manufacture these bags sometimes have mistakes in the printing process that render them unsuitable to their clients.
Rather than throw the bags away, they sell them at a considerably reduced cost. The lb. The more you download the lower the price per bale. Prices for the lb.
When filled and tamped with moistened dirt we call it a working lb. The typical lay flat lb. A working lb. In general, whatever the lay-flat width of a bag is, it will become two- to three-inches These two sizes of bags are fairly standard in the US. Twenty-five pound bags are usually too small to be worthwhile for structural purposes. By the time they are filled and folded they lose almost half their length.
In general, we have not bothered with bags smaller than the lb. Larger bags, up to inch lay-flat width which we refer to as way-too-big bags , can also be downloadd for special applications such as dormered windows in domes or a big fat stem wall over a rammed earth tire foundation.
This provides additional support for the openings, while giving the appearance of a wider wall. By using the wider bags or doubling up the lb. These treated bags and tubes should be avoided. Gusseted woven polypropylene bags are slowly becoming available in misprints. Gusseted bags resemble the design of brown-paper grocery bags.
When filled they have a four-sided rectangular bottom. They are like having manufactured pre-diddled bags refer to Chapter 3. The innovative boxy shape aids in stacking large amounts of grain without shifting. Someday all feedbags will be replaced with this gusseted variety and diddling will become a lost art. Burlap bags also come in misprints. Otherwise, they will tend to split at the seams over time. In a moist climate they are inclined to rot.
Stabilizing the earth inside them with a percentage of cement or lime could be an advantage if you want the look of a masonry wall to evolve as the bags decompose. Burlap bags come in similar dimensional sizes as the poly bags Fig. In the United States, they are priced considerably higher. The cost continues to escalate in the shipping, as they are heavier and bulkier than the poly bags.
Contrary to popular assumption, natural earthen plaster has no discriminating preference for burlap fiber. Most burlap bags available in the US are treated with hydrocarbons. Some people have adverse physical reactions to the use of hydrocarbons including skin reactions, headaches, and respiratory ailments.
Unfortunately, hydrocarbon treated bags are the type of burlap bag most commonly available to us in North America. Untreated burlap bags are called hydrocarbon free. The fabric is instead processed with food grade vegetable oil and remains odorless.
Hydrocarbon free burlap bags require more detective work to locate but are definitely the non-toxic alternative. Perhaps as we evolve beyond our political biases, plant fibers such as hemp will be available for the manufacturing of feed bags. Bag manufacturers can be found on-line or in the Thomas register at your local library refer to the Resource Guide at the back of this book.
We use the flat weave variety rather than the style of tubes that are sewn on the bias. Tubes are what manufacturers make the feed bags from prior to the cut and sew process. Since they are not misprints the cost can be slightly higher per linear foot than the bags.
The rolls can weigh as much as lbs kg depending on the width of the material. They come on a standard 2,yard 1, m roll, but sometimes the manufacturers are gracious enough to provide a 1,yard m roll. Tubes are available in all the same widths as bags. Tubes behave like the bags in that they lose two to three inches 2. TIP: Burlap bags are floppy compared to polypropylene bags. As a result, they tend to slip easily out of the bag stand while being filled. To avoid this annoying habit, pre-soak the burlap bags to stiffen them up prior to placing on the bag stand and filling.
An earthen wall likes to be covered with an earthen plaster that is similar in character. Sandy soil walls like a sandy soil plaster. A sandy soil plaster though, is not as resistant to erosion as a clay-rich plaster mix.
Maintaining the health of the bag expands our plastering options. More bag, more grab. Although lb. Tubes excel for use in round, buried structures, free-form garden and retaining walls, and as a locking row over an arch Fig.
Their extra length provides additional tensile strength for coiling the roof of a dome. They are speedier to lay than individual bags as long as you have a minimum crew of three people refer to Chapter 3.
Outside of the US, tubes also are available in burlap fabric and perhaps cotton. Our personal experience is limited to woven polypropylene tubes available in the US and Mexico. Polypropylene bags are vulnerable to sun damage from UV exposure. They need to be thoroughly protected from sunlight until ready to use. Once you start building, it will take about three to four months of Utah summer sun to break them down to confetti. This can be a motivating factor to get the bag work done quickly with a good crew if maintaining the integrity of the bags is at all a priority.Silt is often present to a certain degree along with clay.
One set of multiple size box and arch forms can be used to build an entire village of houses. Once you start building, it will take about three to four months of Utah summer sun to break them down to confetti. Related Posts.
The light gauge is adequate for linear designs and freestanding garden walls. Each ing material. Earthbag building has been chosen, too, for sites exposed to hurricanes and other extreme weather.