Who Should Care?

Making new adobe construction as resistant to earthquakes as possible is a topic of interest to:

– Architects:

For Architects, offering to design new adobe buildings for hip, wealthy, and environmentally conscious clients can be a savvy way to drum up new business.

– Homesteaders:

Over the last few decades a new back-to-the countryside movement has been slowly gaining steam around the world. Homesteaders and urban retreatists are now looking for ways to build natural homes themselves as cheaply as possible, and for these people, adobe is as a building material that offers low construction prices and beneficial energy savings after the home has been completed. Adobe homes are particularly comfortable and energy efficient in desert regions, tropical locations like Hawaii, and places with long hot summers and mild winters such as the American Southeastern states such as Florida or Louisiana.

– Home Buyers:

Making adobe buildings more resistant to earthquakes may be of interest to those who are looking to commission an architect to design a custom home and then pay a contractor to do the work of building this custom home. Having a custom home built from adobe bricks can be viewed as an environmentally friendly and cost-competitive building option for those looking for a new place to live.

– Building Contractors:

Those in the business of actually constructing buildings could benefit from this report about making adobe buildings more resistant to earthquakes. Building contractors can gain valuable knowledge by developing a better procedural understanding of how to implement earthquake resistant design features into commissioned adobe building projects.

– Self-Builders: 

Some people may not be homesteaders but they might like to save money by building their new homes themselves in towns and cities. Adobe offers the novice do-it-yourself home builders a way to create their new homes on a modest budget if they are willing to put in the work.

– Refugees: 

Since first publishing this blog, Mudman has been a how-to reference resource used by people who have been displaced by natural disasters, wars, and conflicts. Many of the people viewing this report are here because they are looking for practical solutions to desperate housing problems, and this report provides them with valuable technical information concerning ways to make adobe homes built out of desperation safer places to live.

– Charities and Non-Governmental Aid Organizations

Many people who work for various aid organizations have referenced this report in order to help those who are living in severe poverty build lasting and comfortable homes from the earth under their feet. Many of the people who are reading this report are trying to help people who have nothing more than a few simple tools, whatever natural materials are around, and perhaps bits and pieces of modern waste items like old rubber tires and plastic sheeting.

The Research

Research for this writing was primarily furnished by an online adobe building tutorial posted on the website world-housing.net back in 2011. The adobe building tutorial posted on world-housing.net was furnished courtesy of the Earthquake Engineering Research Institute located in Oakland, California. Unless noted otherwise, the information in this report was provided courtesy of the online tutorial mentioned previously. Most of the relevant information presented in the Earthquake Engineering Research Institute’s tutorial was obtained from the Civil Engineering department at the Catholic University of Peru. The Civil Engineering department at the Catholic University of Peru has probably invested more time and money in researching ways to make adobe more earthquake resistant than anyone else, and this reproach has been done because the nation of Peru possibly has the most relevant need to know how adobe buildings will behave in earthquakes.

The nation of Peru might have the most incentive of any place on earth to develop methods for making adobe structures as earthquake resistant as possible for people with limited financial means. Peru has a particular interest in making adobe building as earthquake resistant as possible because estimates posted on the Built Construction Publication’s webpage estimate that around 40% of Peru’s population lives in adobe buildings, and Peru just happens to be located in a troublingly earthquake prone region of the world.

In addition to the structural engineering tutorial provided by the Earthquake Engineering Research Institute, information for this report was sourced from an article co-written by Gernot Minke and Hans-Peter Schmidt for the publication Ithaka Journal. The article by Minke and Schmidt was titled Building Earthquake Resistant Clay Houses and was posted in the online archives of the Ithaka Journal’s website. This article featured in the Ithaka Journal not only provided valuable written information for this report, but this article also provided a supplemental source of diagrams.

The truth is that there are quite a few online tutorials in Spanish posted on YouTube.com which are intended to instruct poor people in Latin America about ways to make their self-built adobe homes more resistant to earthquake damage; however, no such resources exist within the English language. National governments of many Latin American nations produce Spanish language adobe building earthquake awareness videos and also distribute free printed paper literature about constructing adobe homes with better earthquake safety in mind. Many online adobe building earthquake preparation tutorials and printed literature are produced in conjunction with the civil engineering departments of top universities in various Latin American nations.

Governments of many poor Latin American nations produce online adobe building tutorials and printed literature targeted at poor owner-builders because they know that regardless of whatever laws and building codes might sit in legal books, there is effectively no enforcement of building codes when poor people construct their own homes from whatever materials they can find. National governments of many poor Latin American countries also know that their financially challenged citizens will build new adobe homes any way they can out of any materials they can acquire, and these Latin American national governments also understand that the poor citizens of their countries do their building out of sheer economic necessity. National governments of many poor Latin American nations, such as Honduras, are also fully aware that necessity will drive their poor citizenry to build their own homes from adobe without thinking about building codes nor consulting architects and engineers.

With full knowledge of the circumstances surrounding home building in their nations, many Latin American national governments produce online tutorials focused on making informally-constructed adobe buildings as resistant to earthquakes as possible. Many housing departments in Latin American nations focus on providing tutorials to home builders because they know that they would be better off not ringing their hands about building code violations but instead their energy would be better-spent looking for ways to help poor owner-builders make their self-built homes as safe as possible in the event of an earthquake.

Research about the troubling effects of plastic use was primarily obtained from an article posted on the webpage slate.com. The Slate.com article researched for this report discussed the tendency for plastics to rapidly degrade. The Slate.com article researched for this report also talked about why plastic cultural artifacts such as a preserved specimens of the first production run of plastic toothbrushes sold to the general public are now almost completely destroyed due to the chemicals constituting the plastic decaying. Other information about the environmental and health hazards of plastics was found on the United States National Library of Medicine website.

The Reasons this Report was Written

Reason #1.

To Make Adobe Safer for the Poor

The first  purpose of this writing is to provide valuable information concerning how to make adobe homes that are built out of necessity safer in earthquakes. Despite adobe’s fixable earthquake survivability issues, untold millions, and even billions of people in poor nations around the world still reside and work in adobe buildings that are not structurally safe in the event of an earthquake. The billions of people who live and work in adobe buildings standing across the world typically occupy these structures simply because they have no other option.

Given the fact that so many people live and work in adobe buildings regardless of earthquake safety issues, it is is important to provide free information concerning how adobe buildings can be made as earthquake-safe as possible. Despite adobe’s reputation for having real problems surviving earthquakes, if the builders and designers of new adobe buildings stick to a set of relatively simple and easily-understood design rules and building practices the buildings they create can actually be quite safe when earthquakes strike.

Reason #2.

To Pitch Adobe to the Wealthy

This report was written for many types of people, but the secondary focus of this writing is to make a sales pitch for abode construction that is targeted at people with a decent amount of money living anywhere in the world, but particularly those with money who are living in wealthy nations. Contrary to what some may believe, not everyone who is living in a wealthy nation like the United States is personally wealthy, and not everyone who lives in a poor nation is personally poor, so there is still value in promoting the benefits of adobe construction to wealthy people living anywhere. Unlike many of the world’s less financially well-off citizens, wealthy people in general, and especially wealthy people who are also living in wealthy nations, need to be convinced that building with adobe is a good idea; however, most of the world’s people do not need anyone trying to convince them to build with adobe instead of another material.

Many people who live in wealthy nations like the United States often choose not to build with adobe due to concerns about how well a house made from this material will hold-up in the event of an earthquake. If more information about making adobe buildings earthquake resistant was made more readily available to the general public, then it is likely that more people who have options to build their homes from many different materials will choose to have their new homes made from adobe. With considerations about adobe’s vulnerablility to earthquake damage in mind, this report was written in part to inform people who have many other choices in building materials that adobe buildings can be quite safe in the event of an earthquake so long as certain precautions are observed during the building and design process.

Many people living in wealthy nations would be more receptive to building with adobe if they also understood that adobe could offer them money savings during the building process and savings on heating and cooling costs after the construction process is finished.

Aside from being cheap to build, cheap to heat, cheap to cool, and potentially safe in an earthquake, building with mud bricks also offers those who choose this construction material a way to help combat environmental problems. Choosing to build a new home from adobe is one way that environmentally conscious consumers can help fight environmental problems because having a home built from unfired mud bricks requires about 1/5th of the total expenditure of petrol chemicals as a similar home built from conventional materials.

One adobe brick also requires 1/30th the energy to manufacture as one conventionally fired brick, so an adobe home uses a fraction of the energy to build as a conventional brick home. Aside from environmental issues and cost factors, other people who are living in wealth nations might wish to have an earthen home built because they just enjoy the earthy aesthetics of natural adobe buildings and wish to live in dwellings that are as devoid of synthetic materials as possible.

The importance of Keeping it Natural

This report is focused on ways to keep building techniques for new adobe construction as natural as possible. Focusing on natural building materials for new adobe buildings is important because plastics have a nasty tendency to continually release toxic gasses as they decay over time. Most of the plastics in common use around the world today are made with the element antimony in their chemical formulas, and antimony is a toxic substance.

Over time, most plastics decay and release toxic antimony-containing compounds into the ecosystem. Aside from having antimony in their chemical formulas, many plastics are also made pliable in the manufacturing process by using chemicals that mimic female hormones. Synthetic female hormones leaching into the environment from decaying plastics is believed to be responsible for many health problems spanning the entire animal kingdom, so less use of plastics is a good thing.

On a world-wide scale, plastics sitting in land fills specifically effect the ecosystem by leaching antimony and synthetic female hormones into local water tables and eventually the ocean. Presently, synthetic female hormones given off by decomposing discarded plastics are working their way into watersheds around the world. Synthetic female hormones given off by plastic waste has been specifically linked with increased birth defects and reproductive problems in many different types of animals, including humans.

Aside from the toxic substances which plastics constantly secrete over time, plastics also tend to decay a lot faster than most people realize. Plastics tend to break down troublingly fast when exposed to atmospheric oxygen and the UV radiation found in sunlight. Plastic building materials can last a decent amount of time, but only if they are protected from heat, light, and oxygen, and completely protecting construction materials inside a building from heat, light and oxygen is very difficult to do over a long period of time .

Plastic materials can be effectively used in adobe architecture in the form of rubber tire foundations and gravel bag foundations; however, their propensity for toxic outgassing and tendency to decay when exposed to atmospheric conditions make them a less than ideal choice of building material. When looking at the issue of oxidation, it is important to remember that metals such as steel and aluminum also oxidize and degrade quickly when exposed to atmospheric oxygen and moisture, thus also making metals a less than ideal building material over the course of generations

One example of the perishability of plastics involves plastic items of cultural memorabilia such as early plastic purses and jewelry from the first half of the 20th century. Early plastic items of cultural significance are now decaying at an alarming rate in museums, while continuously releasing small amounts of toxic gasses. Art museums are now having a difficult time trying to maintain old items of cultural memorabilia made from plastics.

(Above photo courtesy of Pinterest.com)

Adobe Housing for the Billions

Estimates from the Built Construction Publication of India note that around one half to one third of all the world’s people live in homes built from one style of earthen building or another. As stated earlier, the vast majority of people who live in earthen structures do so because they lack the means to live in anything else, and the people who linhabit earthen building primarily live in rural areas in poor nations. Most of the adobe dwellings around the world are not designed by architects or built by licensed contractors; but instead, these common adobe houses are built on a meager budget by their eventual occupants.

As mentioned earlier, most adobe homes in the world are built by their eventual occupants over a period of weeks or months with the help of friends and family.  Safe or not safe, economic necessity drives poor people in a lot of earthquake prone regions to continue to building and occupying adobe buildings.

The above video link offers a look at how many of the world’s people live in adobe and mud houses. This video was included to provide viewers a sense of how adobe homes for the worlds poorer citizens might appear.

The photograph above shows a typical rural home made from adobe in Jantangerganar, India. ( Photo courtesy of World-housing.net)

The above photograph depicts a set of adobe rural houses in Bangladesh. ( Photo courtesy of terrain.org)

The above photo depicts round adobe houses in an unknown rural area of Africa. ( Photo courtesy of Cheryl Thijssen Alderman’s Pinterest.com account)

The above photo shows a rural adobe home in the south of Mexico. ( Photo courtesy of archleague.org)

Urban row houses made from adobe are the predominant form of urban architecture throughout Latin America. ( Photo courtesy of Overseas Adventure Travel’s official website)

The above image shows a city street in Guatemala lined with townhouses made from adobe. Towns and villages across all of Mexico, Central America, and South America are typically filled with single-story adobe townhouses. ( Image courtesy of Kayak.es)

Upscale Adobe: Despite What You Might Have Heard, Building with Adobe is also a Thing for the Wealthy!

In light of the fact that such a huge portion of the world’s people live in earthen brick homes out of blunt economic necessity, it might tempt people to conclude that building with adobe is a thing better left to the abjectly poor; however, this is not the case. A section discussing upscale adobe homes is in order because people with money who live in earthquake prone areas should not feel that they must avoid building their new homes from earthen brick because of concerns about earthquake safety or social stigmas.

Around the world, many wealthy people live in extravagant legacy homes made from earthen bricks, and these extravagant legacy homes are often located in earthquake prone areas, yet they have been standing for centuries. Many of the old legacy adobe homes that were built several centuries ago function as a type of legacy wealth gifted from past generations to those presently living, and wealthy people in a lot of places still choose to have extravagant new homes made from adobe for many reasons.

Obviously, when someone with financial means is thinking about having a new home built, adobe’s low construction cost is and will remain an attractive feature compared to other building methods; however, adobe has virtues that transcend simple lower construction costs.

One advantage offered by adobe buildings is their ability to keep their occupants both cool and warm in hot arid climates. The fact that adobe walls are basically just big berms of earth means that they do not heat up quickly during the day nor do they cool quickly after the sun dips below the horizon. Adobe’s high heat and cold retention means that during the heat of the day, adobe buildings in places like Arizona will naturally stay cooler than a conventionally constructed wooden home. Conversely, when the sun goes down, desert climates can see temperatures really plummet because there is no moisture in the air to retain the heat from the day’s sunlight, nor is there typically a decent-sized body of water nearby to store and then release brother sun’s energy when sister moon commands the stage.

Another advantage offered by adobe buildings is the fact that they can keep their inside rooms at least somewhat warm during a desert region’s cold night hours because adobe has the ability to absorb and retain heat during the day and then radiate this stored heat back when night arrive and the temperature drops. The upshot of having an adobe home in a desert region with hot days and cool nights is that the owner of a home made of this material will have lower air conditioning expenses during daylight hours and lower heating expenses at night. Despite being associated with people living in poverty, adobe homes offer those with options the added benefit of reduced energy bills on top of a lower construction cost.

Despite offering lower construction costs and improved energy bills in desert regions and the tropics, adobe is often a building style of choice for those with money because they like the aesthetics of adobe and value the local tradition of making building in this fashion. In may parts of the American Southwest, and most notably the city of Santa Fe, New Mexico; even very upscale homes are still built from adobe because those who can afford to have new homes custom-built love the look of an adobe house.

The photograph above shows a nice adobe home in Southern California that was built from architectural plans that are sold the the general public. ( Photo courtesy of twilight-vertrieb.com)

The photo above shows an elegant and expensive home in the Santa Fe, New Mexico area. ( Image courtesy of Pinterest.com)

The image above shows an upscale adobe home built in 2010 in an upscale suburb of San Diego, California. This home is made from adobe and is built to look like an upscale home from California’s Spanish colonial era. ( Photo courtesy of redfin.com)

The above photo depicts a rather large and nice custom-built adobe home that is completely off-the-grid and does not rely on any outside providers for electricity, water, or sewage. ( Photo provided courtesy of survivaluniverse.com)

The above photo shows a newly built upscale home in the Santa Fe, New Mexico metropolitan area. Many of the adobe homes in New Mexico have flat roofs built in the tradition of the Native American pueblos of this region, other adobe homes in this region are built in the Spanish colonial style that is associated with red tile roofs and deep eves that extend well past the tops of a building’s walls. ( Photo furnished courtesy of Pinterest.com)

The image above shows a recently built luxury adobe home that was built located on the outskirts of Santa Fe, New Mexico. ( Photo courtesy of adobeworksinc.com)

The image above shows a very recently built and modern luxury home constructed from locally sourced and simple mud bricks. The house pictured above is a multi-million-dollar villa located on the Mediterranean island of Ibiza.  The island of Ibiza is a well-know international tourist destination and is officially governed as a province of Spain. ( Photo furnished courtesy of blakstadibiza.com)

The image above shows a nice adobe home located in the San Diego suburb of Escondido, California. ( Image courtesy of adobehometour.com)

The video above was included to give viewers a sense of what a new luxury adobe home might be like.

There’s a Whole Lotta Shakin Going On!!!

The Problem with Adobe and Earthquakes.

The problem with living in an adobe homes is that when an earthquake strikes a region where the majority of buildings are built with earthen bricks, the damage is usually worse than it would be if the majority of the building were made of wood. Adobe in particular, is looked upon by architects and civil engineers as a problem from an earthquake survival perspective because adobe structures are made from a material that is much more inflexible and brittle than wood, bamboo, or steel pieces that have been bolted together. Many modern steel-framed buildings are designed to flex in the event of an earthquake, so this type of building is an attractive choice for builders in earthquake-prone areas. Adobe’s inflexible and brittle nature makes structures made from this material unusually susceptible to damage from ground shaking, even compared to other types of earthen building techniques.

For example, buildings made from cob are fundamentally made from the same material as adobe, yet cob buildings are less prone to being damaged by earthquakes. Cob construction consists of stacking layer upon layer of wet adobe material and then mashing the successive layers together to create one continuous piece of earth before the mixture dries. Despite the fact that cob buildings are made out of the same basic materials as adobe building, cob buildings have a much better resistance to earthquakes because when cob structures are dry and finished they are effectively dense and solid single pieces of clay, sand, and straw. Unlike structures made from cob, adobe buildings have a lot of internal joints and places where fractures can occur, and all of the internal masonry joints in adobe structures makes them considerably less robust when earthquakes strike.

Data provided by the Earthquake Engineering Research Institute lists the Pisco, Peru earthquake of 2007 as having left 600 people dead and 75,000 adobe homes destroyed. Estimates are that an additional 300,000 adobe buildings and structures in the area effected by the Pisco Earthquake were damaged to some degree. Troubling statistics of large-scale earthquake damage to huge numbers of adobe buildings are unsettlingly common in poor nations. Chile, Iran, India, and some parts of Central China have many stories similar to Peru’s tale of the Pisco Earthquake when one analyzes records of large-scale earthquake-related devastation to mud brick structures. Without a doubt, the devastation that earthquakes cause in places where a substantial portion of the populace lives, works, and goes to school in buildings made from mud brick is far worse than in places where fewer mud brick buildings are in use.

A typical damaged adobe building after an earthquake. The adobe building pictured above suffered critical structural failure at the corner. ( Photo courtesy of the world-housing.net photo database.)

Adobe is prone to falling in earthquakes, as indicated by this adobe brick home in Bhutan which was destroyed by an earthquake. ( Photo courtesy of the Getty Heritage Preservation Foundation web site archives.)

The image of an earthquake damaged home in the Oaxaca province of Mexico is provided courtesy of a March 19, 2018 article by Richard Betts that was featured on Medium.com. Notice that the above adobe home suffered critical structural failure at the corners.

The illustration above shows the places where an adobe structure is most likely to fail in the event of an earthquake. ( Above illustration courtesy of iitk.ac.in)

The image above shows a corner of an adobe building that suffered structural failure during and earthquake. As stated earlier, corners are one of the most likely spots for a structural failure to begin and then spread to the rest of the building. ( Image courtesy of nachi.org)

The above illustration shows how thicker walls are less prone to upper-tier movement in earthquakes, as are shorter walls; however, these illustrations shine some light into the reason why the uppermost layers of brick are the most vulnerable to failing first when an earthquake strikes. ( Image furnished courtesy of theconstructor.org)

The above photo shows a severe cack that developed in the wall of an adobe home in India after an earthquake registering 6.7 on the Richter scale hit the area. Notice how the crack originated at the top of the the wall. ( Image courtesy of cnn.com)

The above video shows how damaging an earthquake can be when it strikes an area where mud brick buildings are prevalent.

The Solutions

Part 1. In the Beginning

Just Another Brick in the Wall

According the the Earthquake Engineering Research Institute, when looking at the problem of how to make a new adobe construction project more earthquake resistant the issue of building material quality is typically the first issue addressed. For most people living in wealthier nations in contemporary times, the most likely method of procuring bricks for adobe construction projects is to purchase them from a large-scale commercial supplier. Commercially mass-produced adobe bricks will typically have a good mixture of sand and clay with all of the proportions of sand and clay carefully selected to produce the best possible bricks, and these commercially-sold adobe bricks will be well-dried before being offered for sale. If a person is interested in making their own mud bricks, the mixture should be around 70% sand to 30% clay, and some type of vegetable fiber should be added for extra strength.

If at all possible, it is always best to use adobe bricks filled with straw, rice husks, or even some type of animal hair that has been added for extra strength. Luckily, many commercial adobe brick makers offer bricks fortified with fibers. Any plant or animal based fiber added to adobe bricks makes them stronger and less likely to ever crack, and thus less likely to create structures which will fall over or suffer damage in the event of an earthquake.

The mortar that holds adobe bricks together in structures which they form is typically made from the same material as the bricks themselves, for this reason, it is best to add finely chopped straw or rice husks or animal hair to the mud mortar in order to make the mix stronger and less prone to cracking under stress. The same companies that supply adobe bricks frequently offer really good mixtures of mud mortar to bind their bricks together.

Aside from adding plant fibers to adobe bricks and mortar, it is always best to mix the mortar as well as possible to ensure uniformity of the solution, and it is always best to let the adobe mud “Sleep” for at least 24 hours before being used. The term“Sleep”, when applied to adobe mud mortar, refers to the practice of allowing the watered mud mixture to sit in a mixing troff unbothered for a given amount of time. The typical amount of time for mortar to “sleep” is 24 hours.

“Sleeping” mud mortar makes the mix stronger and less prone to cracking under stress because having improved water saturation inside a sand and clay mud mixture creates a more resilient and uniform adhesive mix. Lastly, adobe bricks should be wetted with a hose or soaked in a bath of water for about 5 seconds before being stacked and mortared in the new construction project because wet adobe bricks create a better bond with their adhesive mud mortar.

The above photo depicts an assortment of Adobe bricks from a commercial manufacturer awaiting shipment to a new construction site. ( Photo courtesy of rawculturalcollective.wordpress.com)

One nice feature of adobe bricks is that they can be made rather large, which makes for faster wall assembly and ultimately a more earthquake-resistant structure. This photo was furnished courtesy of Abundant Edge’s website.

The image above shows a decent-sized adobe brick being carried, but if at all possible, it is best to use bricks of adobe that are so large that they must be carried and placed by more than one person. As stated earlier, when it comes to building with adobe, using bigger bricks with fewer mortar joints will create more earthquake-resistant structures. ( Image courtesy of greenbuildingadvisor.com)

Foundations:

The Deeper and Wider the Foundation, the More Secure the Building will be Against Earthquakes.

Aside from making an adobe home as earthquake resistant as possible by choosing the best possible building materials, the architectural designs of adobe buildings themselves helps to make these structures more resistant to earthquake damage. When looking at the design parameters that will help adobe buildings resist earthquake damage, the first thing to think about is the foundation. A solid building foundation makes a huge difference concerning how well a building will resist damage from earthquakes. For the sake of brevity, this report will not focus on evaluating different types of building foundations. The Mudman.blog website also has an entry completely devoted to cheaply building home foundations without needing to hire contractors, so the posting listed previously is a good place to look for a more in-depth discussion about foundation building options.

Many of the adobe homes in the Sacred Valley region of Peru do not have foundations in the convention sense of the word; but instead, the houses rest on naturally occurring and exposed clusters of large rocks. If a cluster of large rocks or a natural outcropping of rock can be found, then this outcropping of exposed rock should be used as a foundation because it will actually make the best possible place to construct for a new building.  A large outcropping of rock or a group of exposed large rocks will make for a building foundation that will resist flooding and earthquakes better than any other type of foundation; however, if no outcropping of rock is available on a planned building site, then constructing a human-made foundation of some type will be necessary.

In order for a foundation to be truly effective against earthquakes, it should be sunk at least 4 feet below the soil line or around 1 and 1/4 meters below the surface of the ground. Many places need building foundations to be sunk rather deep in order to offer a stable place for the building above them to rest when the upper layers of the soil expand from freezing in the winter months; however, even in warm climates where there is no frost line at all, it is still a good idea to sink a building foundation at least 4 feet into the ground as a measure against damage from flooding or earthquakes.

Part 2. In The Design

Aside from starting the building process by building a good foundation and using good building materials, the next thing to consider when designing an adobe structure to withstand earthquakes is wall thickness. The thicker the walls of an adobe structure are, the better the structure will withstand earthquakes. The ideal wall width for adobe buildings is around 3-feet of thickness. Maintaining 3 feet of wall thickness is a good  practice not only from the standpoint of earthquake survivability, but also because thicker adobe walls provide better inside climate control in both hot and cold weather. Adobe walls are not known for being good insulators; however, three feet of adobe brick has about the same insulative value as one foot of solid wood, so having thick adobe walls will still help to keep a building warm in the winter and cool in the summer.

Even if adobe walls are not great insulators, they still have a lot of what is called “Thermal Inertia.” The term thermal inertia refers to a material’s ability to store heat or cold and then to release this cold or heat at a later time.  The energy efficiency of adobe buildings was discussed earlier, but it is still imports to remember that building adobe buildings with thick walls will also help these building maintain a more even internal temperature across the fluctuations of heat and cold associated with cycles of night and day.

When designing adobe structures, there are a few simple guidelines to follow that will increase structural integrity and building safety.

• 1.    Never have any continuous vertical mortar seams running up a wall! Always make sure that the bricks in each layer are staggered so that the mortar joints for one horizontal course of bricks are in the middle of each brick set on the layer below.
  
  The image above shows how to properly set rows of adobe bricks so that there are no vertical mortar seams. (Image courtesy of arizonaadobecompany.com)
• 2.   Make sure that each layer of bricks is level and straight. Use a string and a level to make sure that every layer of bricks is set correctly, otherwise the wall will be structurally weak regardless of its thickness.
  
  The illustration above shows how to ensure that each layer of bricks is level and straight so that the next layer will be level and straight as well. ( Image courtesy of motherearthnews.com)
• 3.   No adobe wall that is part of a building’s main structure should ever be less than 24 inches, or (2 feet) thick.
• 4.   No part of an adobe building should ever be less than 1 foot thick. Only purely decorative parts of an adobe building that are not part of the building’s actual  structure can be as little as one foot thick.
• 5.    No adobe wall should ever have a height more than six times its width. (No height more than 6X Width !) Just for the record, according to the Catholic University of Peru, no adobe wall should be more than 18-feet thick.
• 6.    No adobe wall should have more than 1/3 of its surface area made-up of windows or doors. (No more than 1/3 of area given to windows or doors ! )
• 7.    No opening on an adobe structure should ever be more than 5 feet wide. ( Keep windows and doors below 5-feet wide ! )
• 8.    No opening in an adobe wall should ever be closer than 6 feet to a building corner. (This rule also applies to the corners of walls completely inside of the building!) ( Keep wall openings at least 6-feet from a corner ! )
• 9.    Lastly, walls 20-feet or longer should always have pilasters.

*NOTE * An adobe wall 20 feet long or more should have additional external bracing supports regardless of its thickness; however, from a legal standpoint in the state of California, if an adobe wall has a height to width ration of 4 to 1, then no additional internal or external bracings are needed. The 20 foot wall length rule of thumb concerning adding additional support should always be followed regardless of a wall’s thickness, and regardless of local building codes because long continuous adobe walls are prone to tipping over at the best of times, not just when earthquakes or floods are striking. The additional supports that are often used to reinforce adobe construction are called buttresses and pilasters.

Buttresses are parts of a building where the walls intersecting to form the outer corners are extended out a few feet in two directions in order to give the building additional structural strength in places where it is most badly needed.

Pilasters are additional support columns placed along the sides of walls in order to lend extra support in times of need. Pilasters typically have a wedge-like shape and frequently have a stepped top.

Adobe Structural Strength Made Simple

The above photo depicts an adobe wall in New Mexico complete with a nifty pilaster. ( Photo courtesy of the landsurvivl.com web site)

The above diagram depicts an adobe building with both buttresses and pilasters. ( Illustration courtesy of ithaka-journal.net, Ithaka Journal web site)

Pictured above is an adobe home under construction that incorporates both corner buttresses and mid-wall pilasters that provide support at the outside corners and along the sides of the walls. ( Photo courtesy of thelaststraw.org)

Pictured above is a photograph of an adobe home in Central America that features both corner buttresses and middle-of-the-wall pilasters. ( Photo courtesy of the Building and Social Housing Foundation webpage: bshf.org)

The above image shows how mesh horizontal supports should be integrated into an adobe wall; note that the mesh is added to every other layer of bricks. ( Image furnished courtesy of the City of Portland Oregon’s building department website)

The illustration above shows a close-up photo of juste geo-textiles. The rough jute fabric pictured above is used to secure hillsides against erosion; however, this material also makes nice horizontal internal support for adobe walls. ( Image courtesy of onlinefabricstore.net)

Vertical Internal Support

Placing vertical structural supports inside an adobe wall also lends a large amount of vital support to if an earthquake should arrive. Various vertical structural supports have been tried and tested over the years, but some favorite choices emerge. One popular option for vertical internal adobe wall support is to place lengths of steel rebar inside adobe brick walls. Internal vertical pieces of rebar that lend support to adobe walls should extend from foundations up to the tops of walls.

Vertical internal support methods should be implemented by having the bricks and mortar of the wall laid down around rebar sections as the layers of bricks are put in place. Besides steel rebar, other types of vertical internal support pieces have been tried over the years. Other than rebar, some of the more popular vertical internal support choices for adobe walls are bamboo stalks, reed stalks, and wooden poles. Internal vertical support sections are not intended to support the building roof, they are just used to help keep walls from toppling over in the event of an earthquake.

The above illustration shows how internal reinforcement of adobe structures might appear. ( Photo courtesy of iitk.ac.in)

The video above was created by the company called Danish Tool. The video posted above was placed on YouTube.com in order to demonstrate the effectiveness of Danish Tool’s hand saw that is designed to cut masonry.  A masonry hand saw will easily cut through adobe bricks because adobe bricks are a lot softer than kiln-fired masonry bricks. Using a hand saw to trim adobe bricks might be the best way to go for a homesteader building his own adobe home who has plenty of time and motivation, but not a lot of money.

The video above was posted on Youtube.com courtesy of the Danish Tool Company. This video was posted to demonstrate how a reciprocating saw fitted with a masonry blade can easily trim adobe bricks to fit.

The image above is a screen capture that shows an Amazon.com listing for a Husqvarna brand chainsaw designed specifically for cutting concrete and masonry. Buying a dedicated masonry chainsaw might be a better option for a building contractor due to the relatively high up-front cost of this item. The portability and speed of a masonry cutting chainsaw makes this option quite appealing for any adobe-building work crew who is consistently trimming adobe bricks to fit around vertical supports.

The video posted above demonstrates how to use a common carpentry skill-saw to cut bricks and masonry. The video above shows a man using a regular skill-saw that has been fitted with a masonry blade in order to trim bricks. Using a skill saw to trim adobe bricks is a relatively inexpensive option that might appeal to those building their own adobe homes. (This video provided courtesy of Youtube.com)

The image above is a screen capture from the website of Home Depot. Masonry saw blades that will fit table saws, chop saws, and skill-saws are sold at most hardware stores and come in a variety of sizes.

The image posted above is a screen capture of a listing for a dedicated masonry saw. The image above appeared on Home Depot’s website. The saw pictured above is a bit expensive, so this tool may not be a worthwhile investment for a one-time self-builder; however, an investment such as this might make perfect sense for a contractor who regularly builds with adobe.

The image above is a screen capture featuring a large commercial masonry saw intended for continuous use at large job sites. A piece of equipment such as this might be a sensible investment for a large building company that is working on sizable adobe building projects with regularity. A unit such as the one pictured above would be useful for trimming huge numbers of adobe bricks to fit around corners and within the parameters of vertical internal reinforcements. (This image provided courtesy of nortonabrasives.com)

Once a ring beam has been built and properly fitted to the top of a floor in an adobe building, the ring beam should be covered in adobe mud before the roof is put on, or before the next story is constructed. ( Illustration courtesy of world-housing.net online tutorials.)

Part 4. External Wall Support

Various techniques using external applications have been developed to provide additional structural support for adobe walls in the event of an earthquake. External support systems for adobe walls can be incorporated as the walls are being built or applied after construction of the walls is complete. One technique for externally strengthening adobe walls against earthquakes could be called the “mesh technique”.

The mesh technique involves adding a vertical layer of chicken wire, plastic mesh, or natural goetextiles to the outside of an adobe wall. An eternal support mesh should start at the foundation and extends to the top of the wall. Externally applied mesh is usually secured to the adobe wall by being tightly tied in place by sections of wire or rope that go through the wall and cross the layers of stacked and cemented bricks. Having sections of wire or some type of rope securing the layers of mesh on each outer side of an adobe wall is typically achieved by positioning the lengths or wire or rope into their final resting place during the construction phase.

In addition to having cross pieces of wire or rope running between the layers of bricks, mesh is often secured to the outsides of adobe walls by wooden stakes, and sometimes the external mesh supporting layers are secured in place with large nails. Ideally, the layers of mesh that protect and strengthen the outsides of adobe walls will be held in place by internal lengths of rope or wire in addition to wooden stakes that have been pounded into the bricks. When done correctly, mesh of some type is attached to the outsides of the walls on each side as the they are being built.

The Plaster Caster

Information provided by the Ithaka Journal article written by Minke and Schmidt mentions that adobe buildings can be made stronger and more earthquake resistant by having several layers of earthen plaster or lime plaster added to each of their internal corners. Extra layers of plaster that strengthen the inner corners of an adobe building can be applied by using a simple mold that holds the extra plaster into the corners as the layers of bricks are being set and the wall is gaining height.

Mesh types of external wall reinforcement are typically not visible when an adobe structure is complete, and this lack of visibility for external mesh supports is the case because layers of earthen or lime plaster will almost always cover adobe walls after the construction process is finished. Evidence obtained by the Catholic University of Peru’s Civil Engineering department demonstrates that a thick layer of paster covering all of the internal and external walls of an adobe building makes that building considerably more resistant to earthquake damage.

As pictured in this illustration above, external wall reinforcement is sometimes only applied in areas of high structural stress such as building corners or openings in walls. ( Illustration courtesy of the world-housing.net online photo database.)

Pictured above is a roll of jute Geo-fabric imported from India. ( Photo courtesy of Alibaba.com)

The illustration above was included to provide viewers with a reference for how to incorporate a bottom layer of mesh as well as how to include cross sectional pieces of string between the layers of adobe brick. The sections of string that pass through the wall will eventually secure the external mesh to the finished adobe wall before the plastering an painting happens. ( Illustration courtesy of world-housing.net online tutorials.)

The illustration above was included to show how a finished adobe wall with a proper bottom layer of mesh and a proper set of horizontally placed tie-down pieces of string should appear when all the work is done. ( Illustration courtesy of world-housing.net online tutorials.)

The video posted above discusses the promise of creating earthquake-safe adobe buildings when external mesh is applied to completed mud brick walls

The above photo shows external structural support mesh being secured in place with sections of plastic chording that go through the adobe wall. ( Image courtesy of english.ecosur.org)

The above image shows 2 workers in Peru securing a section of external support mesh by using stringers that cross through the newly constructed adobe wall. ( Image courtesy of english.ecosur.org)

So, what happens when mesh and ring beams are combined?

Part 5.

 Getting Plastered!

After the walls of a new and earthquake safe adobe building have been completed, it is essential that a good coating of plaster gets applied to both the outer and inner walls. Having a good set of plaster layers covering adobe walls is necessary for many reasons. The recipes for making earthen plaster mixtures vary by family, by business, and by region, but the basic recipe for earthen plaster calls for making a mixture based on combining  sand and clay in proportions similar to that of adobe bricks; namely, combining 70% sand with 30% clay.

Some adobe brick recipes include adding some type of plant fibers to the mixture for added strength, and some recipes for making earthen plaster call for adding various animal-based fibers for added strength. Some earthen plaster mixtures also call for adding wood ashes, animal blood, or feces from various animals. Some of the animals that frequently contribute their feces to earthen plaster mixtures include cows, goats, and horses.

After at least one coat of an earthen plaster mixture has been applied to an adobe wall, then allowed to dry, a second layer of earthen plaster is often applied. After layers of earthen plaster have been applied to an adobe building and given the needed time to dry, then an optional layer of lime plaster is often applied.

The above video shows the annual re-plastering of the famous Djenne Mosque in Mali. There is more than one way to keep an adobe building protected with plaster; however,  re-plastering a building one or more times per year is one time-tested method of keeping an adobe building standing century after century.

Thick as a Brick!

What can Damage Adobe Bricks

Wet and Wild!

If an adobe wall has been built with proper earthquake preparedness in mind, there will be both horizontal and vertical internal supports within the walls in addition to having ring beams placed at the top of each story of the building. A properly made adobe building will also have external mesh supports in place on the outside of the walls, and these external support meshes will certainly have some sort of protection from the elements.

A coating of plaster is needed to shield the underlying mud bricks against degradation from exposure to moisture. The atmospheric wetting of adobe bricks can be caused by  condensation as well as wetting from rain.

For a mud brick structure, receiving moisture from either rain or condensation will eventually lead to erosion and structural problem for the bricks and their mud mortar joints. Exposure to liquid water will also lead to more rapid oxygenation of external meshing made from metal, in the form of rust and oxidation. The presence of liquid water inside of an adobe wall will also cause problems for a wall’s organic support structures such as vertical wooden poles or plant-based external support mesh because liquid water promotes more rotting from bacteria.

The above image shows what happens when adobe brick walls are not covered with layers of earthen plaster or lime plaster. The adobe wall pictured above has suffered severe structural degradation due to exposure to both rain and wind. ( Image courtesy of runawayjuno.com)

Getting Winded!

Obviously, expose to water from condensation or rain is bad for the long-term health and structural integrity of a mud brick wall; however, exposure to wind will also slowly erode an exposed mud brick structure. Exposure to wind also leads to structural problems over time because steady winds loosen the outermost grains of sand and clay in an adobe structure when the bricks are dry.

Exposure to winds will certainly erode an earthen brick structure over time, but not as quickly as exposure to water; none the less, wind erosion is another atmospheric exposure issue to consider. Despite its damaging effects, the problems associated with degradation of structural integrity from wind exposure are a distant second compared to the problems associated with exposure to water in a liquid form.

The above image depicts an adobe home in a rural part of Kenya that has seen some notable degradation of its brick structure due to atmospheric exposure to water and wind. ( Image courtesy of powerlub.co)

Ice, Ice, Baby

Too Cold, Too Cold

It just Doesn’t Mesh Well: Dangers to External Support Mesh

Golden Oldies and Golden Moldies

External support systems for adobe structures that are made from some type of metal mesh are not particularly vulnerable to degradation from mold or bacteria; however, both plastic and natural fiber mesh pieces covering an adobe structure are vulnerable to being eaten by various types of fungi and bacteria if they are exposed to the atmosphere without protection. Protecting plastic and natural mesh structural coverings from attacks by oxygen-breathing bacteria and fungi provides one more reason to cover adobe brick walls with a good layer of plaster. Simply covering plastic or natural fiber with some type of plaster will keep them away from oxygen and protect them from the molds and bacterial that thrive in wet, warm, and well-oxygenated environments.

Hello Sunshine!

A coating of plaster over an adobe wall will not only protect the wall from moisture and wind erosion, but a plaster coating on an adobe wall will also prevent outer mesh coverings made from natural fiber from being weakened by exposure to UV radiation. An external mesh support system covering an adobe wall will degrade in the sunlight if it is made from natural materials such as coconut husk fiber of jute, and plastic external mesh coverings are also vulnerable to troublingly rapid degradation if they are exposed to sunlight.

Oxymorons

Exposure to atmospheric oxygen will rapidly destroy both natural and plastic external mesh supporting systems. Oxygen constitutes around 21% of the Earth’s atmospheric gas, and oxygen is essential to all animal life on the planet; however, oxygen is also very reactive and corrosive, and this gas will really degrade both natural and plastic mesh if either of these types of mesh are allowed to be exposed to the atmosphere with no protection.

Ashes to Ashes, Rust to Dust

Plastic and natural materials are often used as mesh to help adobe walls withstand earthquakes more effectively; however, metal mesh is also used as external support coverings for mud brick walls. Metal mesh is less vulnerable to degradation from heat and UV light; however, metal mesh is more vulnerable to degradation from exposure to oxygen. Oxygenation damage to iron-containing compounds such as steel is called rust.

If a steel-based metal mesh is used for external wall support, then exposure to water along with atmospheric oxygen will create an environment where steel will degrade very quickly, and for this reason, it is vitally important to keep at least one layer of protective plaster covering any metal supporting mesh. Outer mesh supports made from non-ferris metals such as aluminum may not rust in the same manner as external support lattices made from iron-based steel; however, aluminum also degrades very quickly if it is exposed to atmospheric oxygen.

The Heat is On!

Exposure to UV radiation, oxygen, and moisture are all bad for the long-term structural integrity of both plastic and natural fiber external mesh support systems; however, exposure to atmospheric heat is also bad for plastics and natural meshes because heat speeds-up chemical reaction in general, so damage from oxygenation, decay from exposure to UV radiation, and bacterial decay are all sped-up in higher temperatures.  Exposure to heat is generally bad for any external mesh covering; therefore, it is important to keep mesh coverings cool by shielding them with a layer or two of plaster.

High levels of atmospheric heat may not be as immediately bad for metal mesh coverings; however, increased levels of heat certainly speed up the development of rust on steel mesh if any water is present, and heat also speeds-up the degradation of aluminum through oxidation.  Oxydation speeds up with increased heat because heat accelerates chemical reactions.

Old Salty

Sodium chloride is the name of a chemical compound that is commonly referred to as table salt. In places that are close to the ocean, salt spray can be constantly wetting an adobe building, and this exposure to a constant mist of salt water particles not only creates an issue with constant dampness, the sodium chloride solution found in seawater is extremely corrosive to natural fibers and plastics, but it is particularly corrosive to steel and aluminum. Given salt’s corrosive nature, it is especially important to keep a layer or two of plaster protecting any mesh covering on a building that is very close to the ocean.  For instance, every part to the Faroe Islands is constantly bombarded by salt spray from the ocean all year round, so any earthen home built in this archipelago is going to need some type of protection against the constant salt exposure.

Many people who build with adobe cover their finished walls with different types of  earthen plaster mixtures that include the juice of some type of plant. The juice of cactuses is quite popular as an  additive to earthen plaster, and the joule of cactuses is quite effective as an ingredient that adds extra strength to earthen plaster mixtures. Adding cactus juice to the mix makes earthen plaster mixtures less likely to crack as well as helping them adhere to vertical surfaces more effectively. Earthen plaster mixtures that include cactus juice are also more resistant to water damage once they have dried. Earthen plaster mixtures that incorporate cactus juice are more resistant to water penetration once they have setbecause dried plant juices create a hardened membrane that is less permeable to liquid water.

The Opuntia cactus is the favored variety for creating cactus juice mixtures the are used as additives in earthen plaster formulas; however, other varieties of cactus, and other types of plants can also produce good additives for earthen plasters.

The different species of  Opuntia cactus are characterized by having paddle like leaves and stems. The Opuntia family of cactuses are primarily native to Mexico, the American Southwest, and the southeastern coastal regions of North America; however, humans have now transported countless varieties of these cactuses to every other continent. At this time, some variety of Opuntia cactus is now growing in any place that does not have truly long and cold winters. Opuntia cactus now grows profusely in Southern Europe, North Africa, all over the Middle East, the Indian Subcontinent, as well as parts of China, and may areas in Southeast Asia. Many parts of subsaharan Africa are now home to large stands of this cactus as well. Opuntia cactuses are also found all over South America and the Caribbean.

If an adobe building is under construction in a very wet and tropical place that does not have any cactus, a similar but less effective additive to the earthen plaster mixture can be made by crushing and boiling banana leaves and then letting this banana leaf stew sit for about three days after it has been simmered. A boiled banana leaf mixture should be made by filling half of an iron or steel pot with a crushed banana leaf mixture and then filling the rest of the pot with water, then letting the mixture simmer for about 8 hours. At the end of the the three days of sitting after the boiling process, the solids should be strained from the mixture with a sieve or cheese cloth.

The image above shows a wild stand of Opuntia cactus growing in Central Texas. ( Image featured here comes courtesy of dirtdobber.org)

The above photo that depicts one of the many species of Opuntia cactus is furnished courtesy of ageanedibles.weebly.com

Other species of cactus besides Opuntia will also work for making cactus juice that is suitable for adding to an earthen plaster mixture. The above image shows a huge stand of very rapidly growing San Pedro cactus that is thriving in Southern California.  The San Pedro cactus is mentioned because it is suitable for making a cactus juice binder for earthen plasters, and this type of cactus can be considered a viable alternative to the varieties of Opuntia cactus because it grows so quickly and achieves such huge dimensions. Although native to Peru, the San Pedro cactus is often found growing as an ornamental and potted cactus in Mediterranean and desert regions around the world.  ( Image courtesy of shroomery.org)

• Notes on Making Cactus Juice

A cactus juice solution is made by filling a bucket or barrel half way with crushed cactus flesh and then filling the rest with water. A mixture of crushed cactus juice and water should then sit for at least 72 hours, or about three days, before it is used to wet an earthen plaster mixture. Many experts on the subject of earthen building recommend letting a cactus juice cocktail earmarked for use in an earthen plaster ferment for about 3 weeks prior to being used. The final mixture of cactus juice should have a consistency similar to that of egg whites or runny yogurt. After the cactus juice mixture has sat for at least three days, but preferably six weeks, then the solid material should be strained out of the mixture using cheese cloth or a sieve.

Kitchen knives can work for chopping banana leaves or Opuntia cactus paddles; however, something a bit heavier that offers a bit more weight for swinging might be more efficient. Machetes and cleavers will work well for chopping cactus into pieces for making cactus juice for an earthen plaster .

The image above shows a banana leaf being chopped into fine pieces for boiling and eventually becoming part of a an earthen plaster mixture. ( Photo courtesy of safebangladesh.wordpress.org.)

The above image depicts banana leafs being boiled to make a natural strengthener and water-proofing additive for an earthen plaster mixture. ( Photo courtesy of safebangladesh.wordpress.org.)

The image above shows a group of rural residents in Bangladesh creating a cactus juice mixture from Opuntia cactus paddles. The final product of this opuntia cactus chopping  process is intended to wet an earthen plaster mixture. The cactus paddles the people in the above photo are cutting and preparing for pulping have all been sourced from locally grown plants. ( Image courtesy of safebangladesh.wordpress.org)

The photo above shows volunteer workers chopping the paddles of a local wild Opuntia cactus. The cactus paddles that are being cut-up in the above photo are slated for getting pulped, placed in a bucket of water, covered and left for several days, and then finally strained. The final product of the process depicted above will be used as an additive and liquifying agent in an earthen plaster mixture. ( Photo courtesy of dirtdobber.org)

A simple cleaver works well for dicing the cactus into the small pieces needed for making the earth plaster cactus juice. ( Image courtesy of wikipedia.org)

The image above shows a cheap machete sold at Lowes stores. Inexpensive machetes like the one pictures above are great tools for chopping cactus into small pieces which is necessary when making the cactus juice that goes into earthen plaster mixtures. ( Image courtesy of lowes.com)

The image above shows a drum filled with Opuntia cactus pieces and water sitting at rest before being left to diffuse into the mixture used to make an earthen plaster. ( Image courtesy of dirtdobber.org)

The image above shows another bucket of cactus plaster juice in the making. ( Image courtesy of returntotheforest.org)

The above image shows a bucket of strained cactus juice that is ready to be mixed with mud and animal manure to form an earthen plaster. ( Photo courtesy of sacredgroves.in)

The above image shows cactus juice being added to an earthen plaster mixture. ( Image courtesy of rootsimple.com)

The Last Straw

Adding straw to an earthen plaster mixture in addition to mixing-in cactus juice, as well as stirring in some horse manure, will ultimately create a much stronger and more water-resistant coating of earthen plaster. The chopped straw that is added to an earthen plaster mix should not be included in excess, but instead, the chopped straw added to an earthen plaster mixture should account for about 1/4 of the volume for a final product. Ideally, 1/4 of an earth plaster’s final consistency should include chopped straw, and the rest of the mixture should be made up of animal manure plus the remnants of crushed and wetted adobe bricks.

The short plant fibers that add extra strength to an earthen plaster mixture can be purchased as animal bedding. Short straw fibers that are ideal to form part of an earthen plaster mixture can also be made by cutting pieces of straw on a wooden block with a cleaver, or machete. Regular kitchen knives will not work well for chopping the straw mix needed to form an earthen plaster because kitchen knives lack the chopping force needed to cut straw with any real efficiency. Axes are also not the best tools for chopping straw because they are quite heavy and often a bit too blunt for efficient straw chopping.

Pretty much any grass stalks can be chopped into straw that is usable for an earthen plaster mixture, as can other plant materials like palm leaves; provided they are chopped rather finely. Pretty much any chopped plant fibers will work as an earthen plaster additive; however, chopped plant fibers need to be dry when they are added to an earthen plaster mixture.

The image above shows some finely chopped straw that is suitable for use in an earthen plaster formula. Straw that has been chopped into short lengths should be used as an additive for earthen plaster mixtures because long straw pieces do not lend themselves well to scarification and scoring of successive plaster coatings. Incorporating long straw pieces within an earthen plaster mixture should also be avoided because long sections of straw do not lend themselves well to being applied around corners. ( Image courtesy of schroomery.com)

Hemp core bedding also works very well as an added fiber to earthen plaster mixtures. ( Photo courtesy of theministyofhemp.com)

The above image shows a bulk-sized bag of hemp animal bedding that is for sale on the website hemptopia.com The hemp mixture seen in the image above works quite well as an earthen plaster additive.

The long stems of wild grasses like the ones pictured above work very well for making an earthen plaster additive fiber. Wild grass stalks like the ones pictured above work well as an earthen plaster additive; however, they must be fairly dry before they can be properly incorporated as a plaster component. ( Image courtesy of wikipedia.org)

The dry grass pictured above would make a good fiber additive to an earthen plaster mixture after it has been chopped into short and dry pieces. ( The above image shows a section of dry wild grass in South Africa. The image above has been provided courtesy of shuttershock.com)

The above photo shows a machete and a block of wood. If nothing else, a sharp machete and a large block of wood are a great set of tools for making a chopped vegetable fiber mixture that is suitable to be added to earthen plaster mixtures. ( Image courtesy of pinterest.com)

The above image is the movie poster for the 2013 film Machete Kills. ( Image courtesy of wikipedia.org)

Cheap cleavers also work fairly well for chopping your own straw for earthen plaster mixtures. ( Image courtesy of eBay.com)

The photo above shows chopped straw suitable for use in earthen plaster mixtures being made by chopping straw inside of a bucket with a weed whacker. ( Image courtesy of journal.goingslowly.com)

The image above shows how chopped straw should appear before getting mixed into an earthen plaster mixture. ( Image courtesy of muddyhands.typepad.com)

Many different mixtures for earthen plaster exist, but one recommended mixture is as follows:

Making the Mixture Part 1.

— 3/4 — 70% sand 30% clay mixture. The earthen portion of this plaster mixture can be made by crushing adobe bricks and soaking the pieces in a cactus juice solution until a mud mixture is present.

–1/4 horse or cow manure

— Use a cactus juice solution to wet the paster mixture. The mixture of clay, sand, and herbivore manure should have the consistency of toothpaste after the mixture is finished.

Making the Mixture Part 2.

After the mixture of clay, sand, and animal manure has been mixed to proper consistency; mix 1/4 the volume of the wet mixture with finely chopped straw and knead the new straw, clay, and manure mixture until the consistency is that of toothpaste. Add more cactus juice mixture as need in order to achieve the proper mixture thickness.

The image above shows a group of people mixing straw, manure, cactus juice, clay and sand together to make a final earthen plaster mixture that is ready to be applied to a newly built adobe wall. ( Image courtesy of permaculturenews.org)

Look at them hippies go! The image above shows a group of happy hippy permaculturist builders making a large batch of earthen plaster mixture and using their legs to knead the fresh mix. There is definitely a danger of loosing a sandal or two when kneading an earthen plaster mixture in the same manner as the photo posted above. ( Image courtesy of themudhome.com)

Some people might want to buy or rent a plaster mixing machine when creating their earthen plaster mixture. Mixing an earthen plaster with a machine is not a bad idea because it will reduce the amount of physical labor needed to make the final product. Using a mixing machine to make an earthen plaster is a good idea because it will also help to ensure a very smooth and consistent final product. Buying a mixing machine might also be a good investment for building contractors or those working on large projects. ( Image courtesy of  constructioncomplete.com)

Using cement mixing equipment is one possibility for making either earthen plasters or lime plasters. Cement mixers like the one pictured above can be rented or purchased in many different sizes to accommodate many different budgets and project needs. ( Image courtesy of kennards.com.au)

The above photo shows two men preparing an adobe wall for a first application of earthen plaster. The wall pictured in the photo above is being prepared for its first coat of plaster by getting wetted from buckets of water and sponges. ( Image courtesy of The Design Consortium’s webpage.)

The image above shows a cob wall being wetted before a layer of earthen plaster is applied. The process of wetting and applying earthen plaster to a cob wall is the same process as preparing an adobe wall for a layer of earthen plaster. The preparation process for plastering a cob wall is the same as the procedure for plastering an adobe wall because cob and adobe are the same material, the difference is that adobe is the same earthen mixture that is made into bricks as opposed to stacked in layers that are mashed together while still wet. ( Photo courtesy of dancingrabbit.org)

Applying an Earthen Plaster by Hand

Earthen plaster can be applied either with a plaster spreading tool or by hand. The photo above shows a newly built cob wall being given a fresh coat of earthen plaster without the use of any tools other than a pair of hands. As mentioned earlier, applying earthen plaster to a cob wall involves following the same procedures as applying plaster to an adobe wall. ( Image courtesy of medium.com)

The photo above shows a worker at the Dancing Rabbit Eco Village in Missouri applying a coat of earthen plaster to an adobe wall by using his bare hand.  ( Image courtesy of dancingrabbio.org)

Applying Earthen Plaster by Using Specialized Plastering Tools

The image above shows a fresh layer of earthen plaster that has been scarified while it is still damp. ( Photo provided courtesy of ilovecob.com)

The photo above shows a fresh coat of plaster getting scored in order to give the next coat of plaster a better means of adhesion. ( Photo courtesy of thebrightideas.co.uk)

The above photo shows a layer of earthen plaster that has been furrowed and is now drying and awaiting a second coat of earthen plaster. ( Photo furnished courtesy of bristolgreenhouse.co.uk)

After Applying a Coat of Earthen Plaster,  Never Use Plaster Made From Conventional Cement!

The above photo shows an a traditional Irish cob home on the west coast of the island. ( Photo courtesy of Elizabeth Anthony Nestor’s Pinterest.com account.)

The image posted above shows a Catholic Mission Church in Southern Peru that was built in the 1500s, and has stood for over 5 centuries. The church pictured above has stood for so long in part because it has a really good coating of lime mortar, and it has also stood for so long because it has continually received regular coatings of diluted whitewash mixtures made from slaked lime. ( Photo courtesy of Wikipedia commons images.)

What is Lime?

Lime is basically the chemical compound calcium carbonate, also known as limestone. When a lime plaster mixture is made, the process involves crushing and then heating seashells that are high in calcium carbonate, or lime can be made by heating pieces of limestone rock that are also high in calcium carbonate. Heating calcium carbonate in seashells or limestone mixtures drives out the carbon in either material by venting carbon atoms into the atmosphere in the form of carbon dioxide gas. After the the crushed seashells or limestone pieces have been properly heated, the mixture that remains will be calcium oxide.

The Definition of Quicklime :

The calcium oxide chemical compound that emerges after a lime firing is finished.

The Definition of Slaked Lime:

Lime has traditionally been made by heating crushed seashells or pieces of limestone in a brick lime kiln fired with wood or coal. Over the millennia, finished lime has also been cooked in simple open fires filled with pieces of wood.

Today, powdered slaked lime is available from many sources, and many hardware stores and agricultural supply companies sell slaked lime in the form of powdered bulk. Unslaked quicklime is also used as a soil additive because it is very alkaline, and for their reason, unslaked lime mixture is often used to treat soils that are a bit too acidic for optimal plant growth.

In the past, lime was manufactured in specialized wood-fired kilns made out of fired bricks that were scattered across the land, and today, modern technology allows the industrial complex to manufacture lime quickly and in practically unlimited quantities. Modern industrially produced lime is made by using automated mining equipment to extract the limestone, and automated ovens of massive scale that are heated by coal, electricity, and natural gas are used to cook limestone into quicklime.

Despite the modern prevalence of Portland cement, slaked lime is still used as a plaster for buildings, and the advantages offered by using traditional lime mortars are slowly becoming common knowledge amongst builders, architects, and engineers. Despite having the conveniences associated with purchasing industrially mass-produced lime, some people still like to make their own lime at home by building a fire and placing lime stone pieces on the top of a large pile of wood that will make a big fire and produce the heat needed to turn limestone into quicklime.

Danger Will Robinson!

The process of soaking quicklime in water produces a lot of heat, and adding water to a quicklime mixture can be quite dangerous, so quicklime should always be added to water, lest a very violent chemical reaction occur. The slaking process where quicklime is transformed into slaked lime is typically not very dangerous; provided that the quicklime is added to a large amount of water, not the water added to the quicklime. The slaking process for making slaked lime is typically distinguished by the water getting warm, or even hot, if the ratio of water to lime is too low; however, the process of slaking quicklime lime is not very dramatic if the process is done correctly.

Raw quicklime is quite alkaline and reactive, so it can burn the eyes and skin, and quicklime dust is not good for the mucus membranes in the throat or nose, so getting quicklime dust in the lungs is not a good thing. Whenever working with quicklime, it is always best to wear gloves, a long sleeved shirt, long pants, goggles, and some sort of breathing protection.

Properties of Lime Mortar and Plaster

Quicklime must be kept submerged in water for at least 3 months before it can be used as a plaster, or used as a mortar for binding rocks or bricks together. Artist’s slaked lime putty that has traditionally been used for making statues as well as forming surfaces for painting frescoes and murals is typically aged for over in water for about 10 years. A long submersion process for quicklime creates a finer lime putty due to the calcium oxide mixture settling into very fine particles, and having very fine slaked lime particles makes for a very smooth putty.

Lime putty that has been aged for quite some time and consist of very fine particles offers builders the advantage of having a coating that is very permeable to water vapor. Having a water-permeable lime coating on a building is a nice feature because it makes  buildings with these types of coatings much cooler in hot weather. Lime plaster mixtures are a lot like the synthetic fabric called Gortex because both lime putty and Gortex allow gaseous water vapor to pass through without trouble, yet both materials will repel water when it is in a liquid form. Despite being a great cooling system when the heat is on, very pure lime putty plaster mixtures are troublingly slow to dry, do not have the highest level of structural strength, and will are vulnerable to getting soft and structurally weak if they are continuously exposed to liquid water. Ironically, despite repelling liquid water fairly effectively, very pure lime mixtures with small particles will become weakened and soggy if they are continually exposed to liquid water.

After a mixture of hydrated lime is exposed to the atmosphere, it slowly turns back into calcium carbonate or limestone by having carbon dioxide in the atmosphere gradually seep into the calcium hydroxide mixture and supply this mixture with the carbon it needs to change back into calcium carbonate. Slaked lime putty can remain in the form of calcium hydroxide almost indefinitely; so long as it is never exposed to atmospheric carbon dioxide.  When a mixture of slaked lime is allowed to rest in water, it is usually kept submerged and covered under about an inch of standing water.  Keeping a slaked lime putty submerged under water is one way to preserve the mixture for an almost indefinite amount of time; however, slaked lime putty can also be kept useable for long periods of time if it is kept sealed in an airtight container.

The Wizard of POZ! What are Pozzolans?

Pozzolans are the term used to describe chemical compounds based on silicon and aluminum that are added to chemical formulas made from slaked lime. Although Portland cement is not traditional lime mortar; none the less, all the recipes for manufacturing Portland cement still call for a certain amount of lime.

Pozzolans are added to help lime putty dry faster and set more firmly. Since Roman times, and before, people have mixed various compounds into lime plasters in order to stretch their mixtures a bit further. Soon after people began mixing other ingredients into lime plasters, they discovered that adding volcanic ash to lime plaster mixtures made their putties dry faster, become much harder when dry, and turn out to be much less permeable to liquid water when finally dried. Soon after volcanic ash was determined to alter the qualities of lime plaster, other ingredients were found to substitute for volcanic ash.

Back in the old days, some of the ingredients that substituted for volcanic ash included certain types of dust made by crushing pieces of old kiln-fired clay pots into powder, as well as adding certain types of ash that were made by burning particular types of plants. For example, the Chinese and other East Asian peoples have a long history of using the ashes from burned rice husks as an additive to lime plaster. The ashes of burned rice husks work quite well as a strengthening additive for lime-based plasters because they are made by burning rice husks, and rice husks contain a lot of silicone dioxide. The high silicone dioxide content in rice husks ensures that whatever ashes are left over these husks are bused are going to be chemically similar to volcanic ash.

Properly POZed

Despite traditional lime plasters seeing less use since the invention of Portland cement, manufacturing pozzolans to be mixed into Portland cement is quite common. Today, there are many different pozzolans used to strengthen both traditional lime putties as well as different types of Portland cement, and manufacturing pozzolans is a big business.

The most common additive for lime plasters today is fly ash. Fly ash is the ash mixture that is left over after coal has been burned. The amount of fly ash added to a lime putty mixture determines that putty’s properties when set, and most lime putties commercially available today have numerical designations that signify their pozzolan content ratios.

Hydraulic Lime is a term used to describe slaked lime mixtures that have pozzolans added to their formulas. In the 20th century, traditional lime plasters have fallen out of favor for building purposes because they set more slowly than Portland cement, are more susceptible to getting softened by standing water, and are less resistant to shock and continual physical wear; however, adding pozzolans can reduce the drawback associated with pure lime plaster. Today, most commercial hydraulic lime mixtures are sold in bulk as powder.

Feebly Hydrolic Lime ( NHL 2 ) –

Feebly hydrolic lime putties typically consist of around 10% pozzolans by volume.
NHL 2 hydrolic lime mixtures are typically applied to building interiors or to sheltered spots on the outsides of buildings. NHL 2 mixtures typically take one week to set after being applied, and feebly hydraulic lime plasters are the most flexible under stress and the most permeable to water vapor.

The image posted above shows a 20-Kilo Gram plastic sack of hydraulic lime that is used to make putties that are commonly used for re-plastering old heritage buildings. The manufacturer of this product is Lincolnshire Lime in England. Lincolnshire Lime primarily sells their products to those who are doing restorations and renovations of old buildings across the British Isles.  ( Image courtesy of lincolnshirelime.co.uk)

Moderately Hydrolic Lime ( NHL 3.5 ) –

Moderately hydrolic lime putty mixtures typically have a pozzolan content between 11% and 20%. NHL 3.5 hydraulic lime plaster mixtures offer a good compromise between having a rapid set time, permeability of water vapor, flexibility of movement, and resistance to damage from liquid water, and resistance to impacts and physical wear. NHL 3.5 lime plasters are often used on external surfaces of buildings that do not receive constant exposure to liquid water nor much physical wear and tear.

( Image above courtesy of lincolnshirelimes.co.uk)

Eminently Hydrolic Lime ( NHL 5 ) –

Eminently hydraulic lime putty mixtures consist of 21% to 30% pozzolans by volume. These eminently hydraulic lime putty mixtures harden within about one day and they are relatively stiff and hard after setting. NHL 5 lime plaster mixtures are typically applied on floors that receive a lot of traffic, as well as other locations that receive nearly constant physical wear and tear like doorways. Eminently heroic lime mixtures are also applied to chimneys and places where exposure to liquid water is very frequent or even constant.

The above illustration was posted earlier to show that external reinforcement meshing can be applied to critical areas where structural failure is the most likely to occur in the event of an earthquake. However, the same areas where external mesh support can be selectively applied to reinforce a building against earthquake damage are also the same areas where high pozzolan plasters can be selectively applied in order to provide more structural reinforcement.

Applying NHL 5 hydraulic lime plasters to the corners of building as well as the tops and bottoms of walls is an effective strategy to strengthen an adobe building against earthquake damage without compromising too heavily on the structure’s permeability to water vapor. ( Illustration courtesy of the world-housing.net online photo database.)

The above video is furnished courtesy of the Primitive Technology blog. This video demonstrates the basic concept of turning calcium carbonate in snail shells into lime putty that can be used as plaster or cement for making masonry walls.

This video demonstrates how quicklime can be made at the farm or homestead level and then slaked in water and made into useful lime putty that can be used for a wall plaster or uses as a mortar mixture to hold bricks or rocks together in a masonry wall ( Video furnished courtesy of the Vantages Youtube channel.)

The video posted above shows another lime “Rick” fire being built and set ablaze in Jamaica.

Making Lime Plaster on the Cheap! Sweetlime.

The actual lime plaster mixture typically involves adding sand to the slaked lime putty and then applying the mixture the the dried earthen plaster layers covering a newly built adobe wall. Many recipes for lime plaster mixtures call for adding animal hair for additional strength.

The typical lime plaster mixture calls for 3 parts sand to be mixed with 1  part slaked lime or lime putty. So, a good base coat lime plaster mixture will be 25% lime and 75% sand with some horse hair mixed in for extra strength.

Sweetlime or Hydrated Lime is a powder that can be purchased in bulk from agricultural suppliers, and this mixture consists of lime that has already been slaked in water; however, this mixture is sold as a dry powder the contains no pozzolans. Sweetlime is added to farm fields to help alkalinize the soil, and even used as a condiment. In India, and elsewhere, Sweetlime is commonly consumed after a meal in order to to help with digestion. Sweetlime offer the advantage of being cheap and easy to obtain, and this formula can easily be mixed with home-made pozzolans to create an inexpensive yet effective plaster mixture.

Home-made pozzolans can be created by crushing kiln-fired bricks into dust or by mixing ash from burnt rice husks or bamboo.

The above image is a screen capture from the website lowes.com. Lowes is a large change of hardware stores and they sell hydrated lime in 50Lb. bags for 9-13 USD.

Slick Rick!

Do It Yourself Lime Putty. Lime Putty From the Rick Fire!

For those who are interested in making their own lime putty from a rick fire: You are in luck! The procedure is not too complicated! After a rick fire has finished burning, The quicklime will need to be collected, ground into as fine a powder as possible, then finally slaked in water for at least 3 months.  After the quicklime has been properly aged and slaked, sand and fiber would be added in order for the mixture to function as a good covering for a set of mud plaster base coats.

A home-made lime putty mixture can incorporate pozzolans in the form of powdered kiln-fired bricks, or ash from burned rice husks or bamboo plants. If there is no availability of pulverized brick powder, or ash from bamboo or rice husks, then another option exists. One possibility for protecting outer coatings of lime is apply a hot lime and tallow mixture.

A hot lime and lard mixture provides a water resistant coating for a final layer, or layers, of lime plaster. A water-resistant lime plaster coating can be made by adding lard or vegetable oil to a mixture of unslaked quicklime before slaking water is added. When a water-resistant coating of lime plaster is made by adding lard to the unslaked quicklime mixture, the water and lime mixture will get very hot and melt the fat into the lime mixture. The lard or vegetable oil in the lime mixture will keep the outermost layer of lime plaster resistant from penetration by liquid water for years.

A lard and lime  mixture can be made by adding 2-cups of lard to 1-gallon of quicklime, then mixing in the water. The exact amount of lard to add to the hot quicklime and water mixture sis not very precise, but figure that creating a mixture consisting of about 1/8 lard or tallow to quicklime is about the right mixture.

The above video shows how lime plaster can be mixed in a 5-gallon bucket using a standard electric drill and lime powder commonly sold at hardware stores and agricultural supply companies.

The above video is a continuation of the first video that shows how to make plaster with standard home improvement or contractor’s tools commonly available at most big box hardware stores.

Using a power mixer like the one pictured above is the best way to make lime plaster from a dry powder base. Using a power mixer will help to ensure a smooth, even, and consistent lime plaster mixture. Drills like this one can be purchased for around 100 USD or rented for a modest price. ( Image courtesy of cnspowertools.co.uk)

Applying Lime Plaster

Each layer of lime plaster should be about 3/8 inch thick, or about as thick as the width of a standard pencil. It is better to apply several thin layers of lime plaster than to try and apply one very thick layer. It is best to give each layer of applied lime plaster the time it needs to thoroughly dry before adding the next layer. Exterior finishes of lime plaster typically have 3 to 4 layers applied, and the corners of walls, buttresses, and pilasters should get an additional 3 to 4 layers of lime plaster for extra strength, so the corners of a building and the areas that are most vulnerable to taking damage from an earthquake should ideally receive up to 7 layers of lime plaster when the building’s construction process is completely finished.

The video posted above shows how to actually apply a lime plaster mixture to the walls of an adobe structure.

Don’t forget to put the lime in the coconut and call me in the morning!

PART 6. Conclusion

Putting it All Together!! Review!

 Review of the Most Important Points!

#1.  Make sure you build your new adobe home on a solid foundation.

#2.  Use good bricks, and use good mud mortar. Using bigger bricks will make for a more solid wall.

#3. Keep the design of the building as compact and sturdy as possible.  Avoid a lot of wide open internal spaces that do not have any additional support.

#4. Follow the Rules of the Road as laid out earlier.

#5. Include pilasters and buttresses.

#6. Apply internal horizontal wall support methods.

#7. Include internal vertical wall supports techniques.

#8. Combine both the horizontal and vertical internal wall support methods.

#9. Do not forget to add a ring beam to the top of each story of an adobe building.

#10. Apply external wall support meshing, and make sure it is secured with strings or ropes that cross through the layers of bricks.

#11. Do not forget to apply at least 2 well-made layers of earthen plaster.

#12. Put a few extra layers of earthen plaster in every one of the inside and outside corners. Apply extra plaster in the right spots for added strength.

#13. If possible, add a few layers of lime plaster for added strength and improved weathering resistance.

#14. Also add a few extra layers of lime plaster to every inside and outside corner for additional strength.

The above photograph was taken by the author in the town of Pisac, Peru. Pisac is located in the Sacred Valley region of Peru. The adobe homes in this image have visible ring beams at the top of each of their levels, and more adobe bricks are stacked above the ceiling on each of the second levels in order to provide shape and support for each house’s roof.