Flexible Form Rammed Earth Construction (Earthbag Construction) Part 1

[Music] when I tell people I'm building a house with Earth bags they immediately look doubtful usually their response is is it stable this comes from the images we have in our minds of all the decaying grain bags we've seen around the country used as temporary retaining walls or drainage control these bags are torn and falling apart and the soil inside them is spilling out when we imagine a house being built with these bags we're doubtful and for good reason now you must try and put all these images out of your mind when I talk about building with earthbags I'm talking about a system of building which incorporates bagging material as one of its components but it also involves proper compaction and plaster to protect the bags from the UV rays and sunlight and Barb Wire between courses which keep the bags from slipping it's not simply stacking bags of dirt on top of one another another name for this system of building is flexible form ramed Earth Construction I think this is a better name because it is more descriptive but it's long and hard to say so we shorten it to Earth bag construction as the term flexible form rammed Earth construction says this is a system of building which uses a flexible form the bags in which damp soil is placed and then rammed until it is firm and then left to dry until it becomes very hard just as you strip away forms from concrete you could then strip away the bags but in this case you can leave the form form in place and simply plaster over it let me delve right into some of the pros and cons of this type of construction the technique is simple and no special skills are required men women and even children can build with bags though no special skills are required there is a certain act to doing the work it can be slow until you get the hang of it there is no cement or rebar in the structure these materials not only cost a lot but have to be transported to the side as well the bag material and Barb Wire are the only materials needed from offsite and they can be easily transported by taxi or bicycle the bags are resistant to termites I did a test in my yard by placing a piece of wood into a bag and placed it on the ground and then placed another piece of wood cut from the same board next to it the board which was completely exposed started showing signs of termites within a short time the board in the bag didn't have ter mites for about 2 months since each course of soil is encased in bagging even if termites do find their way into a course of bags they have to break through another in order to move further it is easy to install electrical and water piping as you build there is no need to chip out channels in the walls you simply pound in a channel while the bags are still somewhat soft you really have a couple of months of working time before the bags begin to get too hard the disadvantage is that you really need to plan out all of your electrical and plumbing beforehand so you can run any pipe or conduit that runs from the inside to the outside of the wall and place nailers in the wall for hanging the hot water heater or for fastening electrical boxes the bags are also flood resistant even if a home becomes flooded the bags ensure the Integrity of the wall the plaster might s off but the wall remains stable after a flood you simply need to clean up and repair any plaster that was damaged the wall will dry out and return to its hard state if you build a dome with the bags your walls slope in to become your roof this gives the structure added strength since an arch and a circle are stronger than straight walls forming a box it also means no Timber and iron sheets for a roof though this is not a huge concern in your Uganda Earth bags hold up extremely well in earthquakes because the walls are somewhat flexible they can't crack like ordinary bricks in the event of an earthquake you might have a crack in the plaster but that can easily be repaired much like the damage you might sustain in a flood an earthbag Dome was tested on a seismic machine in California in the United States and the Machine began to fail before the Dome did earthbag walls offer excellent weight displacement which means even loading of the foundation and less settling due to unstable subsoil earthbag walls are 16 to 20 in thick depending on the size of the bags used these thick walls mean the structure will remain cooler during the day and warmer at night the dense walls will keep the structure at an average temperature this is known as the thermal flywheel effect the disadvantage of thick walls is that partition walls within a house can take up much space that's why we chose to build our partition wall with wood and then plaster it over it an earthbag structure if kept plastered and protected from the UV rays of the sun should last for hundreds of years the bags are essentially plastic so they take a very long time to break down when buried even once the bags deteriorate in several 100 years the soil will still remain strong if protected from moisture damage the disadv advantage of the bags being susceptible to UV rays is that you need to have enough money to complete the work once you start or at least enough to do Plastering as you go let me get right into how we did the Dome first we drove a steak in the ground at the center of our Dome and then used a rope to Mark out an 18t Circle we wanted our finished Dome to have a 14t diameter on the inside and then added in a double thickness of bags and a little extra so we would have room to work we then dug out the soil to a depth of about 3 ft we threw all the top soil and vegetation to one side and put all the lower soil in another pile to be used for filling our bags it doesn't really matter what kind of soil you use any can work just bear in mind that Sandy soils will absorb less water but are more dependent on the bags for their strength clayr soils are more susceptible to absorbing water but they become hard when dry and and depend Less on the bags for their strength any vegetation in the soil will rot and create unstable Pockets once the hole was dug we back filled with one foot of Hardcore and then infilled the top of that with 2in rock don't use soil or even dirty sand to level out the hardcore soil will Wick moisture up through the hardcore and cause moisture problems in the walls and floor as we put in the Rock we placed a metal pipe at the center of the hole which later served as a C of our Compass which controlled the shape of the structure once the pole was in and all the rock was in place and well compacted we then began laying our first course of Earth bags one of the first questions most people ask is how do you get the soil into a long tube of bagging material the answer is quite simple you cut a piece of tubing to the length you need adding about three extra feet for securing the ends you then either tie one end in a knot or do what we did did and gather the material together at one end and then hold it in place by taking a small piece of wire and twisting it tightly over the material you then need some sort of tube to gather the material onto we made a tube out of lightweight galvanized metal sheathing we cut a strip of metal 18 in wide and then rolled that strip into a circle about 10 in in diameter we put in a couple of rivets to hold it in place and then put tape over the ends to protect our hands from the sharp edges of the metal to get the bagging material onto the metal tube you simply pull the open end of the bagging material through the center of the metal tube and then pull it back down over the outside of the metal tube wrap a rubber strap over the end of the bagging material to secure it to the metal tube and to also keep the end from fraying as you work now simply pull the bagging material up through the center and then gather it down onto the outside of the metal tube do this until you get almost all the bagging material on the the metal tube leaving the end you tied earlier hanging out through the bottom of the metal tube we found this process was best done with two people you simply start shoveling moist soil into the center of the metal tube and let it fall to the end of the bag as you fill the bag slowly let the bagging Material off the metal tube keep the slack out of the bag and place it where it needs to be as you go once you reach the end of the tube simply twist the end shut and Tuck the Twisted end under itself and then Tamp the course until it is firm in order to make a perfect circle we attached a horizontal pipe to the vertical pipe we had placed at the center of our hole we measured out from the center pipe 7 ft since we wanted a 14t diameter Dome and placed a mark on the horizontal pipe as we laid our first course we made sure the Inside Edge of the bag was right at 7 ft this gave us a perfect 14t diameter circle with our first course each course after that shifted in slightly reducing the diameter of the circle and forming our Dome shape but retaining a perfect circle with each course we also put a level on the pipe so we could do extra tamping on the high spots to keep our course level as we moved around you'll also notice that as we laid our first course we tuck the edge of a sheet of plastic under it once we reach ground level we then pull the plastic up and over the wall and place another course on top of it to hold it in place this acted as a moisture barrier between the ground and our wall once the first course was laid we used a Tamp to compress the soil we started out using a stick with concrete on the end of it but later used a metal Tamp once the course is tamped down hard place two strands of Barb Wire down on top of it and then Place Another course of bags simply repeat this process until you reach the top of of your wall it's pretty much as simple as that let me just quickly mention something about the soil you are placing in the bags if it is too dry it won't compact well the same is true if it is too wet but before you begin to worry about getting the proper moisture content know this if the soil is too wet it is a little tougher to work with but it will eventually dry out and make a very stable wall simply put air on the side of adding too much moisture to the soil though it will be harder to work with the end product will be better now that you know how to build a wall you also need to know how to make a doorway or a window opening for our Dome the outside ground was 2 feet higher than the inside floor we put in continuous rings of bags up to the 2T height and then placed a wooden form on the wall where our future door would be we then started each course at one side of the door and ended at the other the same is true for the windows once our walk wall reach the proper height we simply put in our forms which were the shape of our windows and packed our courses of bags tightly up against the forms once we were finished building we simply removed the forms and were left with our door and window openings since the walls taper in with each course to form a dome you need to work in bags on the sides of the openings to form a vertical surface to attach the doors and windows as we were building we also placed nailers pieces of treated Timber next to the openings these would be used later for attaching the doors and windows we also put them in the walls where we wanted electrical boxes light fixtures the hot water heater and even where a partition wall would later tie in this creates a simple way to attach things to the walls later there are several ways you can place the bags to form the tops of arches in your openings however you end up doing it just be sure to compact the soil very well so they will hold their shape we placed wire mesh on the bags around our openings to later hold the plaster but I think if I were to do it again I would skip the mesh and simply poke lots of small wires into the surface of the bags for attaching the plaster the wire mesh ended up not working out as well as we had hoped let me go back a moment and talk about the plumbing we place the waste pipe in the wall as we built so that the wall formed a perfect seal around the pipe we also placed some conduit through the wall where our water and electrical would later penetrate the house we also used a board and a hammer to make crevices in the walls where the electrical conduit and water pipe would later run the conduit and water pipe can either be attached using pre-placed Loops of wire like this no it's all going to work or by making long u-shaped Staples of heavy galvanized wire and then poking them into the wall at opposing angles while it is still soft it takes a little planning but as much easier to do as you build rather than trying to chip holes or channels into the walls later on this project we used forms made out of pine they added to our costs but made it easy to make our openings I later sold the forms to another person who wanted to use them so in the end they cost us very little if you don't have the money up front invest in Timber for your forms you can use anything bricks stacked firewood bags of rocks just something to occupy the space while you are building just bear in mind that whatever you use needs to be able to be easily removed later this is especially true of wooden forms you need to build them in pieces and stack them with wedges between them so you can easily remove them when you're finished on this project we place Timbers in the walls at 8 ft for the floor of our lck at this point we also transitioned from the 22in wide bags we used at the base to narrower 17in bags at the top we also quit increasing the amount we overlapped each course and made it constant this gave us a little more space in the Loft and allowed us to put in a window at the top instead of closing off the top with bags the window added to our cost but l in a lot of light we could have kept stepping the bags in more and more and formed a roof with no window had we wanted to keep cost down once the walls were built we poured a concrete floor and then back filled around the Dome with clean rock this acted as a moisture break between the soil and our structure in addition to the plastic sheet we had used earlier we then laid Stone around the base of the structure to keep moisture from wicking up into the plaster we used more wire Staples and poked them into the outside of the structure to give something for the plaster to adhere to we then simply plaster the hole whole thing with cement based plaster the same as you would use over brick on the inside we used a clay mixture to plaster the walls the mix consisted of 20% clay and 80% sand and also chopped up cyle in overhead areas you have to apply the plaster in thin coats otherwise it will fall off the bags you can also use the clay plaster on the outside of the structure this would work best in dry climates remember you don't need the plaster to keep the water out of the wall you simply need the plaster to keep the bags hidden from the Sun if the walls get some moisture in them they aren't harmed structurally and will simply dry out in fact a clay plaster is best for the walls because it allows the walls to breathe and moisture to escape its disadvantage is heavy rains can wash it off quickly cement base plasters won't wash away easily but they tend to trap moisture in the walls we initially tried clay plaster on the outside but found it kept getting damaged by the rain we finally compromised and used cement based plaster on the outside so it would require less maintenance and on the inside we used clay plaster finished with a thin coat of lime plaster to allow moisture to escape from the walls I should also mention to only use Emulsion paints they are washable and more durable than oil paints and they allow the wall to breathe oilbased paints seal the wall and cause problems later even in traditional brick walls we built our Dome with continuous tubes of bagging material we did this because it made the work easier and quicker and we could buy the material from the factory at a reduced cost continuous tubes also had the advantage of adding tensil strength to the structure you can also use bags instead of long tubes though the barb wire gives a structure of tensil strength whatever you choose to use be sure and use new material material which has not been exposed to the sun I also want to say something about the shape of our Dome you can read more about this in a book I found extremely helpful earthbag building by khaki Hunter and Donald kifm but let me give you the basics the quicker an arch Curves in and the less steep the sides are the less stable it is the steeper the sides are and the slower the sides curve in the stronger it is this means not all arches are equally strong just as a guiding principle diameter of a dome should be equal to its height to make an arc that has a height equal to its diameter you need to start with a piece of graph paper for this example we'll make a 14t diameter Dome place a horizontal line on the paper which will represent the base of the Dome place a mark in the middle of the line and draw a perpendicular line to the first line at this point you should have an upside down T now take of the radius which is 3 and 1/2 ft and add this to the radius for our 14t diameter

Channel: The Roundtable

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Length: 19min 5sec (1145 seconds)

Published: Thu Aug 18 2016