Earth
Building with Earth, what are the different methods and the benefits?
Learn more about the different methods and styles of building with Earth. How are the methods and styles different and attributes what are the qualities and attributes of each method and style?
The earth building method and styles described here are Superadobe, Hyperadobe, Sandbags, Compressed Adobe Brick (CEB’s and SEB’s), Poured Adobe Brick, Rammed Earth, Poured Earth, Cob, Earthship, Underground and Hesco. Also learn a little about the pros and cons with each method and style.
Superadobe was invented by architect Nader Khalili of Cal Earth Institute. Mr. Khalili developed it as a possible way for NASA built housing on the moon. He then suggested this method could be used for emergency shelters in disaster areas. Above all, he believed so much in this building style that he later built a 2000sq ft house with 3 bed 2 bath and 2 car garage to show this method could indeed be used to build a comfortable modern-day home.
This method is a very simple concept. Superadobe earthbags come in long polypropylene tubes and are filled with amended (with Portland cement) moist earth, that is then tampered down. Between each layer of earth bags barbwire is attached to the bags to create tensile strength. Bags are often used to create round structures of form of domes, vaults or arches. Building methods like this creates a structure with high thermal mass and the best way to utilize the thermal mass is to allow the wall the “breathe” by not covering it with a insulation of moisture barriers. Covering the bags with an earthen plaster, lime plaster or papercrete would be the best option.
To learn more about building with Superadobe go to CalEarth
Pros
- Simple to build
- Cheap Material Cost
- Thermal Mass
- Organic Feel
- Can be built with little to no skilled labor
- Different Look
Cons
- Labor Cost
- Different Look
- Time Consuming
- Permitting Issue
- Finding a Skilled Contractor/Labor
Hyperadobe was developed by Fernando Pacheco of EcoOca in Brazil as a natural development from Nader Khalili’s development of the Superadobe. The big difference between the two is that Superadobe uses woven polypropylene bags with barbed wire between the layers, whereas Hyperadobe uses a knit raschel, the same material used in packaging fruit. Raschel is a knitted fabric that looks like crocheted fabric. Using Raschel bags is less costly as there is no need of barbwire between the layers of bags as the open netting of the bags merge the earth with the layers below and above.
This method is also a very simple concept. Raschel earthbags come in long tubes and are filled with amended (with Portland cement) moist earth and then tampered down. Bags are often used to create round structures of form of domes, vaults or arches. A building method like this creates a structure with thermal mass. The best way to utilize the thermal mass is to allow the wall the “breathe” by not covering it with a insulation of moisture barriers. For this kind of structure it is best to be covered with an earthen plaster or lime plaster.
Pros
- Simple to build
- Cheap Material Cost
- Thermal Mass
- Organic Feel
- Can be Build to Little to no Skilled Labor
- Different Look
Cons
- Labor Cost
- Different Look
- Time Consuming
- Permitting Issues
- Finding Skilled Contractor/Labor
Sandbags works the same way as superadobe. The only difference is that earthbags are the tube of polypropylene are cut to short bags and closed in one end. Sandbags are often used in the military to build bunkers or used as a barrier to stop or prevent flooding. It is sometime possible to buy these bags at a deep discount. Check for companies that sell misprinted bags.
This is the same method as used with Superadobe. The earthbags come in short bags and are filled with amended (with Portland cement) moist earth and then tampered down. Between each layer of earth bags barbwire is attached to the bags to create tensile strength. Sandbags are often used to create round structures of form of domes, vaults or arches. This building method creates a structure with thermal mass. Best way to utilize the thermal mass is to allow the wall the “breathe” by not covering it with a insulation of moisture barriers. This kind of structure does best with an earthen plaster or lime plaster.
Pros
- Simple to build
- Cheap Material Cost
- Thermal Mass
- Organic Feel
- Can be Build to Little to no Skilled Labor
- Different Look
Cons
- Labor Cost
- Different Look
- Time Consuming
- Permitting Issues
- Finding Skilled Contractor/Labor
Compressed Adobe Brick (CEB) or Compressed Stabilized Earth Block (SEB) also known as Compressed Adobe Brick, is made from earth, clay, sand and aggregate for CEB. If a stabilizer like Portland cement is added to the mix mentioned above the compressed block becomes Compressed Stabilized Earth Block (CSEB) or Stabilized Earth Block (SEB). The fairly dry mixture is compressed into forms and mechanically pressed under high pressure and then dried for a period of 1 month.
Creating CEBs/SEBs both are different from Rammed Earth. Rammed Earth use large formwork into which earth is poured and manually tamped down. This created large segments of wall whereas CEBs and SEBs is like building a brick wall one brick at a time. CEBs and SEBs are also different from Adobe/Mud Bricks. Poured Adobe/Mud bricks are not compressed and thereby does not have the compressive strength of CEBs/SEBs. Some SEBs even have the same or stronger compressive strength of CMU (Concrete Block). Building standards have been developed for CEB and SEBs.
CEBs/SEBs are built into a wall using standard bricklaying and masonry techniques. The mortar used is a simple slurry of the same mix without the aggregate. It is often spread, brushed or piped between the layers. Some CEBs/SEBs have an interlocking shape that makes it possible to dry-stack them. They are made with holes into which rebar are added. Filling the holes are then filled with a slurry gives the structure added strength. In conclusion if both rebar and slurry is added it is a very strong built.
Pros
- Simple to Build
- Easy to Find Skilled Contractor/Labor
- Thermal Mass
- Easier Permitting
- Look of Brick House
- Lower Labor Cost
- Traditional Looking
- Easy to Build Double Wall
Cons
- Supply
- Traditional Looking
- Thermal Mass
Poured Earth Clock/Adobe Brick or Mud Block is amongst the earliest form of building materials found throughout the world. Many native American tribes of like the Pueblo and Hopi have built with adobe for hundreds of years and many building are still standing. The advantage of this build is the thermal mass is so great that it provides a near constant temperature inside year round
A mixture of earth, clay, sand and straw are poured into form and dried in the sun. Compressive strength of poured adobe is not as strong as CEDs or SEBs and can be a challenge to get permitted. There are building codes for this kind of built in the Southwestern States of the US including Arizona, New Mexico and California.
Pros
- High Thermal Mass
- Traditional Looking
- Proven Building Method
- Easy to Find Skilled Contractor/Labor
Cons
- Thermal Mass
- Traditional Look
- Permitting Issues
- Supply Issues
Rammed Earth is a technique of compacting an earth and Portland cement mix into walls. This method is ancient and have been used on nearly every continent. As earth are easily available most places it became a popular building method.
Rammed Earth involve taking a damp earth cement mixture and compacting it between forms/molds creating a wall structure. A layer of moist earth is poured into the form/mold then compacted either by hand or machinery. Once the layer is compacted a new layer is then added and compacted. This process continues until the form/mold is full and then the form/mold is moved up. After the wall is complete the forms/molds are removed.
The compressive strength of a Rammed Earth walls takes a minimum of 30 days to cure.
Pros
- High Thermal Mass
- Quite Living Space
- Constant Temperature
- Beautiful Wall
Cons
- Labor Intensive
- Difficulty Finding Skilled Contractor/Labor
- Cost
- Forms and Machinery Needed
- Permitting Issues
Poured Earth/Cast Earth has become more popular in Europe especially England. Rammed Earth and Cob has used for centuries in England and the natural step was to find a method that used Earth and yet was less labor intensive. The idea of using earth like cement was the natural next step and Poured Earth/Cast Earth was born. Poured Earth/Cast Earth has many similarities to ordinary concrete. It is earth mixed with Portland cement as a binder. The main difference is that cement use sand/ gravel as aggregate and in Poured Earth/Cast Earth the aggregate is earth. Poured Earth use less Portland than a cement mix. Once the mix is done it is then poured into forms just like with a cement mix.
Poured Earth/Cast Earth would be considered “moderate strength concrete”.
Since Poured Earth/Cast Earth is similar to concrete, local suppliers might be able to provide the product which can then be pumped using traditional concrete pump trucks. Standard concrete forms can be used as the framework to have the beauty of the earth walls exposed. It can also be used with insulated forms however this would cover the beauty of the earth walls.
Pros
- Little to no maintenance
- Natural Feel
- Cool due to thermal mass
- Green and sustainable
Cons
- Engineering test of soil before use
- Forms can be challenging to move around
- Finding Skilled Labor
- Finding Machinery/Company to provide the mix
Cob is a very old building method using earth/sand, clay and straw. It was a very popular building method in England in the nineteenth century and many of those building is still standing even though they were built a century ago. Because this method use straw, it is different from Adobe. The straw is used as a binder for the earth.
Building with Cob is normally done by hand. Traditionally is to mix the earth, clay, sand and straw with bare feet and/or hands. The mix is then made into large gobs/cobs and are then added to the building. It is possible to do the work with a backhoe however the charm with this building method is the hands (feet) on the whole process. This is a very free form way of building and will lead to very creative and artistic looking building
Pros
- Proven building method
- Natural Feel
- Creativity and artistic expresión possible
- Change of creating friendships while building
- Cheap to build
- Possible family time well spend.
Cons
- Labor intensive
- Less thermal mass
- Time consuming
Earthship/s was developed and named by Michael Reynolds. As an architect he felt there was a need to recycle materials, create solid structures and use green sustainable building concepts. Back walls are built with tires (recycled) compacted with earth, the front is glass using passive solar. The tires are plastered with an earthen plaster, adobe or cement.
Earthships often use several green features like solar, rain water harvesting, gray water harvesting, cooling tubes, compost toilets and indoor gardens.
Some aspects of this building method is simple like stacking tires and compacting them with earth, however the wood framing needed in the front part of the building can be a challenge.
Pros
- Using recycled materials
- Solid house
- Wind proof
- Great for off grid living
Cons
- Labor intensive
- Can be dark
- Finding a building site can be a challenge
Underground Houses most often are built on a framework and then covered with earth. The framework is often concrete, metal and some come prefabricated in panels made with a composite laminate material. Whichever framework is chosen they are all covered with earth and often have a living roof on them. As they are covered with earth, they have a high thermal mass and therefore are very well protected from weather and temperature fluctuations.
Most times they do require the use of heavy machinery for moving the earth before building and moving the earth back to cover the building. In case of using concrete for the framework there will also be a need for cement trucks. This could make this method of building a challenge in remote areas.
Pros
- High Thermal Mass
- Close to Constant temperature year round
- Protected from most natural disasters
- Will last a long time
Cons
- Expensive to build
- Need heavy machinery to move earth
- Difficult on some building sites
- Labor intensive
Hesco is a fairly new method of building houses. The military have used Hesco for many years as a way to build secure and strong buildings. The forms are simple to build as you place the container where you want the wall build and then fill them with earth. Hesco unites are then stacked to build up the walls. If you use an earth and Portland mix, they be very solid.
The main issue is the lack of design possibilities. They come in a fairly big size and wall are determinate by the width, height and length of the bags. What they lack in design they do have in durability. With a Portland with they are likely to last a lifetime.
Pros
- Solid building blocks
- They have a high thermal mass
- They protect against natural disasters
- They are simple to build with
Cons
- They can’t be moved once filled with earth
- They are limited in design
- Heavy machinery is needed to fill the bags