The First Rammed Earth Wall At Rancho Mastatal

The First Rammed Earth Wall At Rancho Mastatal

By Thea, Apprentice 2025

During the recent natural building workshop, Rancho Mastatal saw the beginnings of the first rammed earth wall on the property. Together with Benito, Nic and Ali, the apprentice team had the satisfying job of completing the wall. It is situated in the new Pilón construction and stands as another example of natural building and more specifically, the uniqueness of rammed earth.

So what exactly is Rammed Earth Construction?

Good question. Rammed earth is an ancient method of construction used by civilizations such as the Assyrians, Babylonians and Persians over 10,000 years ago. Essentially, rammed earth is a mix of soil, sand and water mechanically compacted into a high density framework, which is then stripped and allowed to cure. Simple right?

Rammed earth is a simple yet highly effective building method known for its affordability, durability, and efficiency. This technique mimics the natural formation of sedimentary rock—over time, as the structure settles under its own weight, it becomes increasingly compressed and therefore stronger. This would explain why structures such as The Great Wall of China and Berber Tribesmen settlements in the Atlas Mountains are still standing today.

Traditionally, this method uses sandy soils in arid or moderate climates such as Morocco and Australia because it has great natural thermal regulating properties, offers termite-free lodging, can be quick and sustainable; providing materials are taken from nearby land, or the site itself. However this wall does tend to erode and deteriorate when faced with wetter climates and seismic regions; and does require extra insulation in temperate regions. To increase durability, stabilizers such as Portland cement or lime are commonly added, as well as rebar to increase stability in earth-quake prone areas; but this does come with the cost of higher processing and more embodied energy.

Recipe for our Rammed Earth Wall

When testing mixes for the Ranch’s earthen wall, the team experimented with ramming raw earth (soil, sand and water) as well as stabilized earth (with added lime) to test durability and sturdiness. The raw earth mixture didn’t pass the test due to the clayey composition of the soil here at the ranch- soil with a high volume of clay is highly absorbent, which causes shrinkage and cracking in your walls. The lime provides structure and stability when added into the mix and after successful testing of the stabilised earth; the final mix was devised as a 2:4 ratio of sand to soil, hydrated with 20% lime. This worked well for the ranch, but it is always crucial to do your own tests due to different soil types, choice of aggregate, and what your are asking of your wall.

how to make the wall

framework and tools

Decide where you want to situate your wall. As previously mentioned, rammed earth does not fair too well with consistent water; so using it for a shower wall probably isn’t a good idea. In our case, the wall was to act as a sturdy and aesthetic privacy barrier for the compost toilets. What will your wall be sitting on? In this case, the earthen wall was to sit on a foundation of concrete blocks which also determined the width and length go the wall.

The first step is to gather or make the tamper (tool for compression) ensuring it is not too large for your framework but heavy enough to tamp down the earth. It is also crucial to build the framework itself which will determine the width and length of the wall. The framework must also be easy to dismantle to allow for removal and re-construction. Having several identical frameworks could be a nice alternative to this process, however, since this was a small-scale wall, we worked with two forms which could be removed and leapfrogged up the wall. It is important to consider how to make the frame as sturdy as possible. It has to withstand the force and vibrations from the tamping as well as the compression of the earth. For instance, the framework we used had two large screw attachments in the end quarters (covered by thin PVC pipe to ensure for easy removal) that could be tightened from both sides. Furthermore, foreseeing that the corners of the wall are the most likely places for erosion and damage to occur (ie, getting knocked and touched), they have been flattened off to create an elongated octagonal shape.

Making the Mix

So, now we have the framework and tools ready, we need to make our mix. For this, we followed our ratios and mixed with a drill in large barrels; gradually adding water until the mixture would hold together when compressed, but not too sticky that it would be pulled off the wall with the framework. We colored half of our mix in order to create a multi-toned, wave-like effect, and left the rest as a ‘base’ coat to layer in-between as well as in the middle of the wall (where the colour won’t be visible). This is the creative part of the process, and we repeated this step with various colors and tones depending on what section of the wall we were working on.

The Human Powered tamping Method

Being diligent to tamp everything well, including the edges and corners

Gather a driver, rubber mallet, several clamps, some thin pieces of wood, some creativity and some patience and hey presto you are ready to build.

Once the first framework has been set in the correct place and secured or held firmly down, it can be filled. The first section of wall will determine the trajectory of the rest of the wall, so placement is crucial. The next step is to layer the earth mixture and firmly but carefully tamp down; paying special attention to the edges. If you would like to add color, it is a good idea to cover the sides only, and fill in the middle with base mix in order to save on pigment. If you have access to different colored soils, you can just use the tone of the soil to create these color striations. When tamping near the long cross-sectional screws, we would take thin pieces of wood and a rubber mallet to compress areas that would be missed by the larger tamp.

Sealing the top of the wall

When the layers are nearing the top of the framework, the next nerve-wracking step is to carefully unscrew the lower framework and leapfrog it on top of the next. Clamp down, reset the screws and continue to layer and tamp. If the frames are not clamped together, you may find some mixture makes it into the gaps in-between; creating a fine line. Not a necessarily a problem- it can add to the aesthetic of the wall. Furthermore, the type of framework used will leave holes in the cross section of the wall. Again, these can add to the look, or be filled in afterwards with some mix. As the wall grows, so must the builders. We created a platform to stand on in order to tamp the upper layers with ease.

To seal and waterproof the top of the wall, we poured a colored concrete mix as the final layer before removing the last framework.

Now it is crucial to stand back and admire your wall, paying special attention to its unique pattern and beauty.

How sustainable is this rammed earth wall?

It is too soon to say what the longevity of this new construction will be. It has not yet ensured the hundreds of visitors it will see over the coming years. Will it withstand minor tremors? Will the decision to add lime and seal with concrete help it to fair in the humid jungle climate? Will it withstand the many hands that will touch with admiration? Only time will tell.

Because this was such a small wall in the overall building, and in an area with little consequences, we had the luxury of experimenting with this technique to see how well it holds up, for our knowledge and others that want to learn about natural building.

In the mean time, I hope you find some inspiration from this post and happy building!

Want to Learn More?

Check out one of our annual natural building classes to get theory and practice in earthen construction and plasters.

check out these past blogs

How to Build with Wattle and Daub in Timber Frame Construction: A Natural Building Method for the Tropics

Tadelakt - Water Resistant Lime Plaster

How to Make an Earthen Floor

How to Build with Wattle and Daub in Timber Frame Construction: A Natural Building Method for the Tropics

How to Build with Wattle and Daub in Timber Frame Construction: A Natural Building Method for the Tropics

 By 2025 apprentice Aaron Wilson

If you’re building in the tropics, it’s essential to choose methods and materials that can stand up to humidity, heat, heavy rain, and pests—without sacrificing sustainability or beauty. That’s why here at Rancho Mastatal, we rely on natural building techniques like wattle and daub combined with timber frame construction to create structures that are both resilient and aesthetic.

This traditional method, used for centuries by many different cultures throughout the world and in tropical and subtropical regions, is incredibly well-suited to the environment. The timber frame provides a strong, long-lasting skeleton made from locally sourced lumber, while wattle and daub infill offer not only privacy and protection but also cheap, efficient, breathable earth-based walls that help regulate temperature and moisture inside the building that modern conventional building methods fall short on.

This article will walk you through how to build with wattle and daub in a timber frame structure, step by step—from frame design and wall weaving to daub mixing and natural finishes. Whether you're planning a homestead, an eco-retreat, or just want to explore hands-on natural building methods, this guide will give you the practical foundation you need to get started.

Now, let’s get building. 

Designing the Timber Frame Structure

Designing a resilient timber frame structure is the foundation of a successful natural building project. In the tropics, durability and ventilation are key. At Rancho Mastatal, we typically use dense, rot-resistant hardwoods sourced locally, such as Pilon, for their natural resilience to moisture, termites, and fungal decay. A post-and-beam layout works especially well, offering open spans and flexibility for interior walls made with wattle and daub. We elevate the structure using reinforced concrete stem wall for its resistance to earthquakes and provides good access around the entire house to spot termite activity before it becomes a structural problem. When sketching out your frame, be sure to plan for large roof overhangs (Dutch gable roof) to protect earthen walls from driving rain and include ample openings for cross-ventilation to support passive cooling. A well-thought-out timber frame doesn’t just support your building—it sets the tone for how the entire structure will perform in the tropical environment.

Preparing The Wattle Framework

Wattle refers to the lattice work that creates the rigidity and structure for our daub (earth mix). We use bamboo as this lattice, because we grow it, but wattle can be made from any natural local material (wood, reeds, branches, etc.)

If you are using bamboo, your next step is to prepare the bamboo lattice (wattle). We harvest our bamboo from clumps growing on and around the Ranch. This typically takes a group of people in one of our all-hands-on deck work parties to process a bunch of bamboo at once and get it treated before installing it into the walls. The process involves a group cutting down bamboo branches and cutting them to a predetermined length. Then another group will take some machetes and wooden mallets to split the bamboo pieces into smaller strips, about 1 inch wide or so, not too wide and not too narrow so that they can be attached to the timber framing.

The bamboo strips will then be soaked in a solution of borax and boric acid to treat it for protection from insects and fungal decay, especially in environments like the tropics. After soaking the bamboo needs to be left out to dry for some time, 1 to 2 weeks or so. This method is great because it is non-toxic to humans and animals and doesn’t alter the color of the surface significantly. Once the bamboo is ready it can either be stapled to the timber framing or woven together to form a lattice, we opt for the staple method for the sake of time and ease.  

Mixing the Daub

Daub refers to our earthen mix, which contains various ratios of clay, sand, and fiber. If you haven’t done any soil and mix tests yet, now is a perfect time to do so, now that your wattle is ready. During our training we made several different examples of mixes with different ratios of clay, sand, and straw to see how each one performed once it had dried, even though our instructors Ali and Nic already know the optimal mix, this an essential exercise to do on your project to get the right mix for your specific site. At Rancho Mastatal we are using a 1-part soil (ours is clay rich), 1-part sand, and 1- part straw for the daub mix, or simply 1:1:1. This gives a good balance of glue from the clay, compressive strength and cracking reduction from the use of sand, and tensile strength from the fiber, which is straw.

We start by laying out a tarp as close to the area we are going to daub as we can to minimize carrying buckets of mix around. We then pour the sand on the tarp first creating a crater in the middle to put the wet clay in to avoid it from just spreading out all over the place. This is where the fun begins as you need to be ready to get a bit muddy! Stomp, stomp, stomp then burrito is the strategy. The burrito part is probably the most import step in ensuring the materials get incorporated evenly and are not just sticking to the tarp. This simply involves flipping the mix over by pulling one end of the tarp over to the other in the rolling fashion, then stomping on the rolled material again and beginning to add in the straw each time as well as spraying the mix with water as needed to help get the right consistency, not dry but not too soupy. When it looks well mixed you can grab some and feel how it interacts in your hand, checking for stickiness and firmness. When this is done go ahead and put the mix into buckets and bring them to your wall for daubing.

Applying the Daub to the Wattle

Here at the Ranch, we like to get our hands dirty so we will partner up and each person will scoop up a handful of daub and begin weaving it into the lattice. It’s important to make sure that each side gets their mix in-between and through the horizontal strips rather than just laying it on flat, otherwise your mix may fall off the wall. As you start to fill up the wall with earth mix you can check the thickness with a screed which is set to the desired depth of your wall from the face of the timber. We opt for slightly thinner walls (3-4”), this thickness allows us to cover our electrics and plumbing, uses the minimal amount of mix, and accentuates the timber frame nicely. If you put on too much mix you simply use the screed to scrape off the extra and mix it in elsewhere, if your mix is too thin you will notice a gap between the wall and the screed. The goal here is an evenly flat wall at the right depth. You do want to leave your wall with some key on it, this key will ensure your next plaster adheres better.

That pretty much wraps it up for this article. The next step will be applying a level coat clay or lime-based plaster before the final finish coat. We will not cover this in this article but there are other’s that cover this here. Also consider joining the Ranch for one of their yearly natural building workshops, to get practice in all these techniques.

Final Thoughts and Learn More

By combining wattle and daub with timber frame construction, you can create a durable, sustainable, and climate-appropriate structure that blends seamlessly with the environment. For a deeper dive into Natural Building at Rancho Mastatal, check out our full blog page.

Interested in learning more? Join a natural building workshop at Rancho Mastatal to experience this technique firsthand!

What is Natural Building?

What is Natural Building?

By Core Team member Ali Ostergard

One of our guest cabins

We have been building our infrastructure with natural and local materials since the Ranch’s inception in 2001. Our homes are all sculpted from the earth beneath our feet, and we continue to develop and learn along the way about how to perfect natural building in this challenging tropical environment. There is something very special about the feeling of a home when you know the story behind where the materials came from and all the work and joy that went into the whole process.

So what is natural building? I would say the definition goes deeper than just constructing buildings with “natural” materials. After all how do we define what natural is? Is plastic natural? Technically it comes from oil, which comes from the earth, so one could argue that it is natural in origin, although you could also argue that due to the heavy amount of processing that goes into converting it into plastic moves it into the realm of a non-natural material. What about concrete? Again, it is just composed of portland cement (a mixture of limestone, shale, and other natural minerals), gravel and water. Yet concrete is often seen as a material not to be used in natural building. Why is this? It has something to do with the massive environmental effects it is causing through its production including, the high energy consumed in the mining, manufacturing, and transporting of cement, along with the related air pollution, making cement (a main ingredient in concrete) a large contributor to greenhouse gas emissions. Somewhere around 10% of current world greenhouse gas emissions are from the production of cement, and that number is predicted to raise 12-24% in the next thirty years.

Yet all this bad mouthing on concrete, and we still need this material in our modern world. For what it provides, we don’t currently have anything to replace it. For certain uses in our modern construction world, we need concrete; there is simply no other material that does what it does. Where we have gone wrong in the use of this amazing building material is that we now use it everywhere! Concrete is overly used in every building, home, city, and suburb. There are many other natural and more sustainable materials that could be used in a lot of areas in modern construction, but instead people resort to using concrete. Walls are a fantastic example, there really is no functional purpose to make your walls out of concrete, there are so many materials that have less environmental impact and perform much better than concrete as a wall system.

Buildings around the world account for about a third of greenhouse gas emissions. The time has come to reimagine our current housing choices. We are going to get nowhere on this planet without realizing we are a part of nature. So the more natural you can make a house, the better off you’re going to be.

Adobe brick shower with tadelakt lime plaster finish

Circling back around to what is natural building then? Here are some things we are considering when choosing building materials for our structures:

• Locality- how far did that product come before arriving at your building? How natural is your material anymore if it’s coming all the way from China, when we could use what is locally found here in Mastatal?

• Organic- how fast will that material break down or go back to earth after its lifespan? Buildings come and go, generations change, natural disasters strike, modern conveniences evolve. What happens to that building when it’s no longer of use? We are proud to say that if we took off the metal roof, and removed the few plastic electrical items in our buildings, the jungle would take back the rest of the materials. They would literally go back to where they began.

• Processing- how much processing was involved to get that material from its raw state into what you are using now? The clay that we dig out to build our walls goes through very little processing compared to the zinc roofing sheets.

• Longevity- how long will this material last? Ultimately we want and need our structures to last for a significant amount of time. If we build a home that is constantly falling apart, needing repairs, the maintenance on that is going to be too much and we are probably going to give up. With a good design and a bit of know-how, natural materials can last in your home for your lifetime and there are examples of naturally built homes in virtually every type of climate that have lasted at least 100 years (some lasting much more).

At the Ranch we have been practicing and perfecting the art of natural building, especially for tropical climates. After decades of trial and error and fine tuning every detail, we are pretty confident we have come to a pretty dang perfect natural building style for tropical architecture.

Bernie’s Bunkhouse- a good showcase of what a typical building is made of here

Our natural homes consist of:

• Timber frame- a style of post and beam construction that uses only wood and no metal fasteners. Using locally, sustainably sourced and milled species.

• Earthen walls- in a style referred to as wattle and daub, a mixture of sand, clay and straw that is applied to a bamboo lattice. We also use adobe bricks in many aspects of the building.

• Clay and lime plasters- both used in different scenarios.

• Earthen floors- again a mixture of sand, clay, and straw.

• Concrete foundations- yep, that controversial product. As I mentioned earlier, concrete is an amazing building material for certain aspects of building. In our case we live in a highly seismic area, concrete is currently the best material to use for the safety and longevity of our buildings.

• Zinc roofing- also a heavily processed material, but in our area where we receive 4-6 meters of rain a year, this is the most sustainable material in the long run for our natural homes. We often say the beauty of these natural materials is you add water and they return to a workable state, but this is also their weakness. Therefore good protection in the forms of your roof and foundation are essential in the longevity of your building.

Over the years we have made an effort to build in a style that also appeals to the masses. We have plenty of unique and very different styles, but it was important for us to develop building styles that would be equally at home in an urban or rural area. We feel like all too often natural building has fallen into the bracket of only being suitable for the owner builder, or the hippies, or the isolated farm and we would like to create a style that is pleasing to a larger audience and demonstrate its flexibility in applications.

An example of the artistry clay plasters can have

We each have a part to play in this paradigm shift. When our buildings are having such a direct effect on the climate and our health, we are a part of that, and we have to make the choice of whether we would like to change that.

Patagonia put out a short film on the natural building movement, specifically looking at straw bale building. As Yvon Chouinard said,

“The solution may be for a lot of the world’s problems is to turn around and take a forward step. You can’t just keep trying to make a flawed system work.”

We have been offering natural building workshops for decades. These building classes teach people about building with timber, clay and lime in any climate. We are excited to be able to offer a heavily discounted natural building class for Central Americans in Spanish each year too.

Learn More

Want to get hands on practice and theory in many of these mentioned natural building techniques? Join us for one of our yearly workshops.

Related Blog Articles

Building an Adobe Shower with Tadelakt Plaster

Design Ideas for a Sustainable Home in the Tropics

How to Make an Earthen Floor

Lime Plasters Are In

Lime Plasters Are In

By Anthony, Apprentice 2020

Plastering is an ancient tradition in the building trades that continues to hold cultural importance in modern times. Amongst the typical plasters that can be found in the building world include clay, gypsum, portland cement, and the focus of today’s blog, lime. The rich history of the use of lime in the plastering trades can be traced back to all continents. Of particular note are the styles that have emerged from Italy and Morocco, as well as the beautiful examples that are found in Japan and the ancient Mayan temples of Mexico. This craft is experiencing a resurgence through the increased global interest in natural building.

A clay carving with a lime fresco background

Tadelakt (water resistant lime plaster) shower- Read our blog about how to make an earthen/tadelakt shower

Why people love Lime Plasters

Lime plastering as a craft form has endured the test of time due to its versatility and the accessibility of limestone as a building material. When produced and applied with care and experience, lime plasters yield an elegant finished product. Some of the many benefits of using lime include high vapor permeability (‘breathability’), flexibility, autogenous healing, stickiness, and durability. Perhaps of greatest interest is the ‘breathability’ factor, which contributes to drying interior spaces and the general avoidance of condensation inside buildings. Additionally, where other stiffer plasters, such as cement, might fail due to the formation of large cracks, flexible lime plasters have the unique characteristic of self-healing (‘autogenous healing’) with which micro-cracks are naturally filled with ‘free lime’. This contributes greatly to the durability of ancient structures, particularly in seismic zones.

Hawk and trowel

Overview of the Lime Cycle

Understanding the benefits of using lime in our buildings, let’s review the source of these plasters by exploring the lime cycle. Our desired binder begins as calcium carbonate in the form of limestone, coral rocks, or sea shells. This base material is heated to around 900°C (a ‘cherry-red heat’) where it undergoes a chemical change by giving off carbon dioxide gas and forming calcium oxide (quick lime), a highly reactive, dangerous compound. Don’t mess with it. From here, quick lime is hydrated by combining it with water and calcium hydroxide is formed. At this point, our hydrated lime is being prepared for final application by slaking it, that is, to be stored in water. Once we are ready to use this hydrated lime, it is prepared in a mix with aggregate and fiber, according to our desired use of the plaster. Generally, multiple coats are applied with each successive layer receiving a thinner application. The final layer, or our finish coat, can be applied as thin as 1/16th of an inch, or even less.

Lime Plaster Finishes

There are many ways that lime plasters can be applied to create different visual and textural effects. This is where the magic happens. Some of the well-known finishes include frescos, venetian plasters, lime wash paints, and tadelakt. All require a detailed attention to the timing and moisture levels during their application.

Benito Steen stoning our tadelakt shower

Fresco design

Learn Lime Plastering in Natural Building Workshops in Costa Rica

The annual Natural Building Workshop at Rancho Mastatal in Costa Rica is focused on developing simple and elegant wall systems for sustainable homes using readily available natural materials. The course focuses on Natural Building techniques, such as wattle and daub, adobe bricks, cob, earthen floors, and the mixing and application of multiple kinds of plasters, including clay and lime. Workshop attendees have the opportunity to learn from some of the most experienced natural builders in Costa Rica, and to develop their skills in creating elegant lime plaster finishes such as tadelakt, fresco, and venetian plaster. This year’s course was attended by people from more than 10 countries, and was just as diverse in its variety of natural building techniques demonstrated.

Students practicing different plasters and techniques during our annual workshop

Pigments, fibers, sands, and more

Want to learn more?

Hope you feel inspired to begin learning the ancient art of lime plastering. You can really beautify and add special touches to your home and spaces with a variety of different lime plastering techniques.

If you want some hands on practice and instruction, sign up for our annual Natural Building Workshop.

Also check out Benito Steen’s YouTube channel all about natural building techniques.

Stay tuned for the wide array of upcoming courses conducted at Rancho Mastatal in Costa Rica.

Check out these past blog articles about natural building techniques we practice and teach:

How to Make an Earthen Floor for Your Sustainable Home

Natural Building & Clay Carving: Add Artistic Expression to Your Home

Design Ideas for a Sustainable Home in the Tropics

Natural Building & Clay Carving - Add Artistic Expression to Your Home

Natural Building & Clay Carving - Add Artistic Expression to Your Home

By Mateo, Apprentice 2020

Clay. Oh noble clay. O beautiful, hardy, earthy clay. Whence forth did you come, and how did we ever come to deserve such a wondrous material? Art thou merely a dream... oh

A Dorodango, using a handful of clay from our soil

Oh sorry... didn't see you there. I was just entranced by this ball of clay I have here in my hand. Why do I have clay in my hand you ask? Well, why DON'T you is what I say!

I'm here today to preach the wonders of clay, and more specifically to try and convince you to go out in your backyard this afternoon and dig a hole and play in the mud. You'll be so busy having fun, you might not even realize that you're making art at the same time! So buckle up, and let's dive into the world of Clay Carving!

Clay carving with polished lime plaster on the center and a timber frame structure

What is Clay Carving?

Now first off let's get one thing straight. I'm not talking about your classic clay pottery, or your other classic clay sculpture. I'm talking about Clay CARVING. What's the difference you say? Go ahead and take a look at those pictures all around these here words. These are all examples of clay carvings we have adorning different natural buildings here at Rancho Mastatal.

Clay carving is the process of building up layers of clay in differing colors or textures, and then carving away those layers in forms and shapes to create a 3 dimensional "relief" carving. This technique transforms ordinary, flat walls into amazing works of art, and can drastically transform and elevate a space. It also goes hand and hand with natural building techniques like earthen walls and clay plasters.

Building your Clay Carving Canvas

Now that you know what it is, you might be wondering, where would I even do this? The answer to that my friend, is wherever you want.

Well, maybe not wherever. But you could do it in a lot of places! In your home, in your garden, your backyard, your school, your workplace (if your boss is cool), etc. etc. If that 's too much choice, here, take these tips for building yourself a canvas to work on.

Build a rectangular panel out of plywood. You can line the edges with 1x1 in pieces of wood to contain the plaster and clay plaster mix as you apply it. You will probably need to apply a base coat of cement based plaster with some acrylic glue in it to bond to the plywood and create a rough surface for the clay to stick to. A 2' x 3' panel would make for a nice size to practice on, and if you like how it turns out, you can clean the edges up and place it in the garden, on your porch or hang it from a wall somewhere! (If you're thinking about, or already are, building a house, then consider adorning whole walls with an artistic carved clay finish. The beauty of your natural building will astound!)

Practice panels in our annual natural building course

OR make a cob bench, and add a clay carving to the back. Cob is one of the simplest and most versatile natural building materials. By just mixing clay, sand, and straw in the correct ratio (more on ratios in a bit), you can then stack and mold the cob into flowing, beautiful shapes, and the surface will be nice and rough for further Clay coats to stick to. Stack it up into a bench shape in the backyard, and then leave yourself a nice flat area on the back for your carving to live.

Getting Natural Building Materials

At this point, there are two directions you can take, or maybe you can walk right in the middle. You can either buy good quality, pre sifted sand and clay from hardware and/or ceramic supply stores, or you can go into your backyard and dig up some Earth and see what you find.

Soil is different everywhere, and amounts of clay and sand vary widely between locations. Regardless, you'd want to dig down at least 6" (though this varies by location) to get past the topsoil, and then do some tests to figure out how much clay and sand you have at hand. This could mean doing the jar test, filling a jar with a handful of soil and water and letting the parts separate out, sand falling to the bottom and clay settling on top. Or you could send out a sample for precise testing if you want to be scientific about it. Once you have a better idea of what ratios of material are in your soil, you can make a mix.

This process is essential in most natural building endeavors, and is a skill that takes practice. Trust me on this though, getting to know the Earth around you will bring benefits beyond just what you can build with it.

Making a Clay Carving Mix

Clay is naturally flexible, while sand is naturally rigid. Sand provides structure, while clay binds a mix together. The right balance of the two will give you a material that you can carve into shape, and have it stay.

Finding that balance is part of the fun. Try mixing in different ratios, starting with 1:1, and taking some notes along the way. What feels good to work with? What drys well without cracking? What lets you carve without crumbling? Some tips to start: too much clay will cause cracking, and too much sand will cause crumbling. Too wet of a mix won't hold its shape or stay on a wall, and too dry will be hard to apply.

Sample sizes of sand, clay, and straw ratios

Remember, that as you carve you will reveal lower layers of clay. Try finding or buying different colors of clay, or mix in pigment or colorful materials to create contrast and interplay between layers. And don't be in too much of a rush to apply the next layer; if it's not dried enough, your layers may blend together.

Finally, a note on tools

You can do all of this with your hands and a razor blade, laying material down, smoothing it out, and cutting it into shapes once dry. You can also use different tools like floats and trowels to smooth and flatten layers, and other tools like chisels and awls to aid your carving. Start small and easy before you spend money on new tools, and look for used tools or tool rentals before a big purchase.

Summary Step by Step

To wrap up, let's go through a step by step and some final tips:

1. Gather all your tools and materials. It is better to do all your preparation before you start. Think through what you will need from start to finish, including clean up!

2. Prepare your canvas. Whether you're building a new surface or applying to an old one, make sure that the surface is rough or "keyed" so that the clay mix has more surface area to bind and hold on to.

3. Create your mix. Do small batches for tests and samples before going big, so you have an idea what it will turn out like before spending a lot of time and energy. Also keep in mind that you can get finer (as in smaller sand) and creamier (as in more clay) as you add more and more layers, but you'll have to apply in thinner and thinner layers to prevent cracking as these ratios change.

4. Apply your first layer. Smooth and flatten as much as you desire. Let dry enough so that you can add a new layer without the under layer blending with your new layer. You may need to wait several days between layers in a humid climate.

5. Apply second layer. You can now add as many layers as you want to carve away, altering color and texture between layers as desired.

6. Carve away clay to reveal the art within! A razor blade is effective due to its sharp edge, though any knife could work. The basic process is to cut with the knife the outline of the shape, then carve out the interior (with an awl, screwdriver, or even stick). Cut at an angle, widening outwards from the surface, to create cleaner lines and forms. You can smooth the revealed surface beneath with fingers or smooth stones. Dig and carve deeper to reveal more layers beneath!

7. Clean up when you're done, especially your tools to prevent rust. Finally, if you want your clay carving to last longer or be water resistant (though not water proof) you can apply a hardening oil like linseed oil.

Exposing the different layers of plaster. You can see here the design sketched in, and the first coat of red clay plaster being carved away to expose the underneath grey plaster.

Let the Artist in You Soar!

Now you have an expanse of clay before you, a blank canvas to express yourself upon. Have fun! Feel the warmth and beauty of the clay, and tap into your inner artist. Get dirty and share the experience with someone else! With some practice, you might be surprised what kind of beautiful things you can make with just a bit of Earth!

Working on the Rancho Mastatal mandala on the outside of our food processing kitchen. The yellow is a frescoed lime plaster.

The clay carving done on the outside of a small cabin. The entire project was completed by our 2017 apprentices!

Want to Learn More?

For a great video of a beautiful clay carving in action watch this video by The Nito Project.

To get hands on instruction and learning in clay carving and other natural building and plaster techniques come join us for our annual Natural Building and Plasters Intensive.

Stay tuned about our annual workshops!

Timber Framing: A Real Application of Sustainable Forestry Management

Timber Framing: A Real Application of Sustainable Forestry Management

By Anthony, 2020 apprentice

The deforestation problem that constantly threatens our global forest resources is one that we can overcome. To accomplish this, though, we must again learn to give our forests real value. The main idea here is that our forests must be more economically valuable in their current state than they would be under competing land uses. If not, they will be deforested.

Cattle Pasture and Forest,

Latin America’s diverse and astoundingly beautiful forests are constantly under threat. Here, deforestation occurs when forest owners decide that they can earn more money doing something else with their land. Forests are routinely slashed and burned to make room for agricultural systems, cattle ranches, infrastructure, urbanizations, and mining, to name a few alternative land uses.

One real strategy to conserve our precious forests is sustainable forestry management, a practice that selectively and sustainably chooses trees to be harvested within a forest in order to use their timber for construction, furniture, tools, and artisanal products. When well planned and carried out respectfully, sustainable forest management gives way to increased biodiversity within a given forest, offers employment opportunities in rural communities, and, perhaps above all, makes a forest’s continued existence economically possible.

Timber Framing

Rancho Mastatal is putting this plan into action. This Costa Rican-based educational farm offers workshops in diverse areas with an emphasis on sustainable community living in the tropics. One of their flagship courses, ‘Introduction to Timber Framing’ leads workshop attendees through the process of building a simple and elegant timber frame home. Starting with the basics, such as tool sharpening and laying out a timber using the square-rule method, the workshop ends in climactic style on raising day when the students see their work come to fruition. After many days of focused, methodical work chiseling and sawing, the timber frame home is assembled in a swift group effort in a single morning. The workshop is an ideal combination of focused individual development and group camaraderie.

Sourcing sustainable wood

The timber used for the construction of Rancho Mastatal’s timber frames originates from two main sources, both of which are sustainably and carefully chosen: selectively-felled trees from managed secondary forests, and trees planted specifically to be harvested for their wood. Additionally, the national context of the timber frame workshops is significant. Rancho Mastatal exists in a nation aiming to be carbon neutral by the year 2021. So far, large-scale national strategies have been based on a renewable energy sector, yet little has been done for real improvement in the construction sector. Here Rancho Mastatal leads the way toward carbon neutrality while conserving tradition.

To be original, one returns to the origins. Sustainable forestry management and timber frame buildings are ancient traditions that must be practiced in order to be culturally conserved. By integrating these traditions into a business plan through its educational workshops, Rancho Mastatal and its core team aim to realize an originality apt for modern times.

A nice display of the different joinery in one post

Stay tuned for the next blog Timber Framing Tips: The Things You Didn’t Know You Needed to Know.

Join us in 2021 for our Timber Framing Workshop to get hands on practice and instruction on this beautiful and traditional form of building.

Building an Adobe Shower with Tadelakt Plaster

Building an Adobe Shower with Tadelakt Plaster

By core team members Nic & Ali

We recently completed another adobe shower and thought we would share with everybody how and in what order it was executed.  The building blocks of the design were adobes that we made with our 2018 apprentices and student groups that visited us through the year.  In total we used around 500 adobe bricks at 5” x 5” x 10”.

What is an Adobe brick?

An adobe brick is mixture of sand, straw and clay, formed in a mold and sun dried.

How to make an Adobe brick

Start by making tests with your soil, if you are not sure what that means, read this article. Where we live we have an abundance of red clay soil. Using our soil, which is almost pure clay, we can use 1 part soil to 3 parts sand as a good starting point, depending on variations in the soil we may need to mix at 1:4 too.  We add about ½ a part of long straw too, this gives the adobes some additional tensile strength.  We then put all our ingredients on a tarp and begin to mix it together. Once the adobe mix is ready (one uniform color of mixed sand and clay) the mixture is put into an adobe form. When packing the forms make sure to fill all the corners! The form is then removed and the brick is left in the sun to dry until it dry enough to be moved and stacked.  In our climate during the dry season this takes 3 to 5 days.

Steps to making a shower

1. Planning

As with all successful projects the key is good planning.  We like to use a program called SketchUp to mock up all of our designs, lay out foundations, the frame and even plumbing. Every detail must be planned in advance this makes sure that the correct provisions can be designed in and made in advance.

2. Foundations

For our shower we used concrete blocks cut in half so that they could form the curves that we wanted. A shower is going to be a wet area so it is important that you think about this during the planning stage, where will the water drain to? Are my pipes embedded in my foundation? How is my roof going to be attached. In our design we decided to have a separate Timber Frame to support the roof structure.

Step 3 - Adobe

The first course of adobes were attached to the foundation using a cement based mortar this helped them bond strongly to the concrete foundation. 

Step 4 - Bond Beam

From the second course upwards we used a sandy clay mortar for the adobes.  Every 4 courses of adobes we made a cob bond beam for extra strength.

Step 5 - Gringo Blocks

Wooden hollow blocks (known as gringo blocks) were put at the end of each wall to attach in the wooden frame for the doors and a hollow plumbing box was installed where all the plumbing would be inserted for the shower handle. In Costa Rica the plumbing parts easily purchased in the local hardware store are terrible and always leak so we made most of the plumbing accessible from the outside. It is generally a good idea when making your initial design to plan for replacing parts in the future.

Step 6 - Frames

The door frames were installed at this point and they were screwed into the Gringo blocks.  The door frames were also tied into the adobe structure using some mesh, we used what we could locally find which is what they sell for chicken fencing. You could also use a variety of natural alternatives, attaching them to the wood and plastering them in to the wall to give them extra stability.

Step 7 - Leveling

A leveling coat was then applied to sculpt and level the walls, this was tied into the door frame to give extra support too.

Step 8 - Tiling

The vertical surfaces of the concrete block were tiled to provide a plaster stop on the bottom edge were the plaster would meet the tile.

Step 9 - Plastering

A lime base coat was then applied over the earthen leveling coat. Whilst this basecoat was still damp (before it started wicking moisture again) we applied the tadelakt mix (1 part fine lime sand and 1 part lime).   We did the Tadelakt like this as we had such a large continuous surface area to plaster and needed the time to work it all.

Step 10 - Tadelakt

Once the plaster had dried enough we stoned and soaped the wall using our homemade soap.  The Stearic Acid in soap reacts with the Calcium Hydroxide (hydrated lime) to make Calcium Stearate which is highly hydrophobic and one of the reason Tadelakt is considered water resistant. Read more about Tadelakt here.

Step 11 - Mosaic

The remaining horizontal surfaces were tiled using different colored swimming pool tiles.

Step 12- Exterior Plaster

We used some of our left over mixes to do a base coat and finish in one pass, adding some pigments to alter the color. We used floats and darbies for the base coat and a sponge float and flexible Japanese trowel for the finish

The shower was ready, once the plumbing was connected all that was left to do was enjoy the cool water in these wonderful showers. The two sides of the shower are pretty similar, the main difference being the color combination on the tile mosaic floor. Do you want to bathe in this epic outdoor shower? Come stay with us at Bernies Bungalow!

want to learn more?

Dream of building your own home, outdoor space, or maybe just a simple earthen garden bench?

With over 15 years of experience building and teaching natural building techniques, the Ranch is a perfect setting to get inspired and hands on learning.

Join us for one of our upcoming natural building focused workshops. We generally host a workshop in natural building, timber framing, and/or bamboo construction annually.

How to Make an Earthen Floor for Your Sustainable Home

How to Make An Earthen Floor

Why Build an Earthen Floor?

This Earthen Floor adds a wonderful warmth to the Ceiba Lounge

Earthen floors add a great earthy touch to your sustainable home; whether that’s in your cob house or conventional stick frame home. They have more give than concrete or tile, meaning they are more comfortable and easy on your feet. Earthen floors can be durable and last a long time, but are not the best material for all spaces in your home. They will break down faster when there is a lot of moisture on them or heavy items dropped on them. So places like your kitchen and bathroom are not ideal locations for an earthen floor. Earthen floors work great for bedrooms and living rooms.

Mixing by hand gives you a great feel for the mixture

Here at the Ranch we have been practicing and perfecting our earthen floors for more than 15 years. We strive to create sustainable homes from natural, local materials. Natural building is one of the ways we practice green living. We have seen what works and what doesn’t in many different structures and spaces throughout our community. After having an earthen floor in our kitchen, a space that produces three meals a day for an average of 30 people, and after repairing patches again and again, we realized this space is too heavily used for an earthen floor. Spaces like our guest cabins are perfect for earthen floors. Of course with hundreds of people going through these spaces they wear down over time. If you correctly lay an earthen floor in your home, and take care of it, they should last you for a long time. 

Wooden guides can be used to help keep the correct thickness

How We Build Our Earthen Floors

Base and final coat in a sample, always make tests!

Here in our tropical environment, with the materials locally available to us, we have finally figured out a bomber earthen floor. Here is a simple step by step guide on how we lay an earthen floor.

An earthen floor is comprised of 4 different layers

·       Water proof membrane

·       Tamped gravel (optional to increase total depth)

·       Compacted road base (mixture of sand, clay and gravel)

·       Two layers of final floor (mixture of sand, clay and chopped straw)

Make sure your samples are large enough to be representative!

Before you begin make samples! Always make samples for anything you plan on building; whether that is for your cob house, outdoor pizza oven, or natural plasters. We recommend making at least 3 samples with different ratios of clay, sand, and straw. These should be at least 1 meter by 1 meter to get an accurate example of the final product. 

Steps once you find the correct ratios

1)     Lay down a waterproof membrane, wrapping it up the inside of the stem wall.

2)     If you need to increase the depth of your floor height you can add tamped gravel.

3)     Compact your road base. Minimum depth is 4 inches.  

4)     Lay down your first layer of final floor. We do ¾ inch thick. Let completely dry. 

5)     Lay down your final layer of floor. We do ¼ inch thick. This can be troweled smooth to close any holes. Let completely dry. 

6)     Paint multiple layers of linseed oil/thinners combo at 3:1 ratio. This provides a protective coat that will increase the longevity of your floor.

Want to Learn More?

Perfecting an earthen floor takes time and practice. If you are trying to create a sustainable home consider using earth for your floor and throughout your home.

If you would like to get some hands on experience in natural building join us for one of our upcoming courses check out our workshops page for our latest offerings.

References:

Earthen Floors - A modern Approach to An Ancient Practice By Sukita Reay Crimmel & James Thomson

Timber Framing in the Tropics

Timber Framing in the Tropics
By Tim O'Hara

The rainforests of Central America might not be the first place that you think of when you hear the term “timber frame construction”, but with initiatives in Monteverde and Mastatal, Costa Rica is starting to make a name for itself in the region for this post and beam building technique. We started to build the infrastructure of Rancho Mastatal Sustainability Education Center in the small rural community of Mastatal, Costa Rica in 2001. At that time, we did not seriously contemplate this age-old technique of joining large timbers using mortise and tenon joinery. There were no local, established wood mills in the area in 2001 nor had we ever built anything in this manner. In addition, the portable Alaskan mills used by local sawyers are not up to the task of producing a 6'x6'x12' member straight enough to work using the square rule method that we would eventually be introduced to.

The possibility of building a timber frame structure on the Ranch's campus began to gain traction after our introduction to SKIP DEWHIRST and LIZABETH MONIZ in 2003 when these two Vermont-based builders came to Rancho Mastatal to teach a natural building workshop at our site offered through Yestermorow Design/Build School. After a successful first workshop, they began coming down every year to teach courses, though with a non-timber frame focus. Skip, a seasoned timber framer, eventually started to inquire about the possibility of sourcing long, straight, large timbers so that we could begin to incorporate this type of building into our natural building education programming and our infrastructure. During a conversation in 2006, we decided together to give it a try and started planning a 2007 workshop that would focus on the construction of a 10'x15' cabin on the edge of the rainforest. We would in due course call it La Casucha, meaning little rustic house in Spanish. We set about trying to source the cut list for the design that Skip had come up with. When we finally received the wood delivery for the class, banano was the first term I heard uttered by our talented and local worker ALEX HERNANDEZ. Banano in Spanish, as you can probably figure out, means banana in English and is not an endearing term when referring to a piece of wood to be used for the construction of a rectilinear home. It took us more time to plane the timbers to ready them for laying out the joinery than it did to actually cut the joinery with our chisels and mallets. Banano has since worked its way into our building lexicon and is uttered a bit more frequently than we'd like. But that's life in the rural tropics.

For those of you reading this in the comforts of your first world home, we do not have access to a lumber yard or a box store for our building needs. Nor at that time did we have easy access to a bandsaw mill. Almost all of the wood that we used for building purposes had to be straightened, planed and cut before even thinking about a layout. Fortunately for us and others interested in sourcing local wood, in 2010, a local man named CARLOS SOTO set up a portable bandsaw mill about a ½ mile from our town center. From that point forward we were able to more consistently obtain reasonably straight timbers and our foray into timber framing has not waned since. We now have a combined total of 9 timber frame buildings at the Ranch and in our small community. The practice has revolutionized the infrastructure of our organization and how we look at wood as a building material in our timber-rich ecosystem.

We have access to and have used many different species of wood for our projects and continue to learn about the different qualities that each have. There is much less written about the characteristics of the tropical woods that we use than the commonly used temperate species in North America. Much of our learning has happened through trial and error. Pilon, or bull's blood, is a heavy, resistant hardwood that we expected would be good for pegs until we realized how short-grained it was. Melina, a resistant softwood species originally imported from India, is a decent candidate for frames though the wood can be tricky to work with due to inconsistent grain patterns. Teak, another non-native wood increasingly common in Costa Rica, has a tendency to be knotty from some local suppliers and prone to termite damage if harvested too young, as is commonly done in our area. For most of the species that we've used, sourcing wood from older trees, keeping your chisel razor sharp and making sure that your stock of patience is full are all keys to a successful and strong frame.

Since opening our doors in 2001, natural building has been one of our focuses. Our site is considered by some to be a leader in the relatively small natural building movement in Central America. All of our buildings are small, simple and nice on the eye with a focus on using materials that we can source in our region. To do this requires a lot of work, an abundance of persistence, and the willingness to slow down the building process. As our campus has organically grown, so has our network of people working in and interested in natural building. We've had the honor of working with and befriending a number of leaders in the sector including BILL, BENITO and ATHENA STEEN, RYAN CHIVERS, LIZ JOHNDROW, MATTS MYHRMAN, CHRIS MAGWOOD, SKIP and LIZABETH and others. We've also had the privilege of experimenting with other wonderful natural building resources such as clay, bamboo and lime that are so rich in our region. It's been a wild ride full of successes and failures but increasingly our infrastructure is starting to catch the eyes and fill the hearts of many a natural building lover with timber frame construction the crux of our building world. Even though this building technique has a shorter history in Central American compared to other parts of the world, our experience has shown that it's a relevant choice for our environ. We plan on continuing our experiments with timber frame construction and invite you to come and join us on our ride to discovering the beauty of building in the tropics.  Hope to see you in Mastatal soon!

OPPORTUNITIES AT THE RANCH, IN THE REGION AND BEYOND

Japanese Natural Plastering
Interested in natural plasters?  Join us in March, 2018 for a unique experience learning about Japanese Plastering at Rancho Mastatal.  

Aerie Backcountry Medicine Semester in Wilderness Medicine
Join Aerie for its Semester in Wilderness Medicine at Ranch Mastatal and Montana this winter and spring.  The field portion of this course runs January 31 through April 15th.  The Semester offers 15 upper-division UM credits, EMT, Wilderness EMT, Swiftwater Rescue and Avalanche Rescue certifications, as well as training in LNT, wilderness survival and wilderness navigation.  Students will live for a month at the Ranch, will help organize and run a free health clinic in Zapaton and will complete rotations in the Emergency Room as well as on an advanced life support ambulance.  The cost for UM students, including room, board and all certifications, is approximately the same as in-state tuition at UM, and students can use their AmeriCorps awards as well as their financial aid.  

Japanese Cooking at Rancho Mastatal
Love Japanese Food?  Join us March 20-23 for a fantastic culinary immersion in Japanese cuisine during our Japanese Permaculture Cooking:  An Introduction to Japanese Cooking and Permaculture

We hope to hear from some of you with your updates and stories!  Thanks to all of you out there that make the Ranch community so strong and special.  

Abrazos, 

The Ranch Crew

Re-plastering: What will be unveiled?

Re-plastering: What will be unveiled?

On the building list, one of our goals is to correctly re-plaster old structures to enhance their look and highlight our unique architecture. Over the last couple years we have slowly been giving our old structures new face lifts. Using lime plaster techniques that we have been learning, practicing and perfecting, we have transformed various run down plasters into beautiful canvases of art.

This process of remodeling never fails to reveal a variety of problems and headaches. We have learned that you never know what will be exposed once you start to take apart a wall for re-plastering and patching. So, as we have been going back to old structures to prepare for a face-lift we have encountered many different troubles due to past techniques.

In order to apply a new lime plaster you must remove all material from the wall that seems loose or may not allow the lime to adhere well. This is done by chiseling off old plaster materials, which can lead to more of the wall falling apart than planned. Once you’ve taken off the old materials you must go back and fill in the gaps created in this process; which can be a lot of gaps! The quality of the original wall is a big determining factor in how quickly (or not so quickly) this whole process will take. Therefore determining the amount of time a project will take is extremely difficult; you can make an estimated guess, but depending on what you uncover the estimate can change drastically. As in any remodeling job you just never know.

You can tell the difference between the walls that were built patiently with skill to those hurried by the physical amount of material falling off. There are a variety of reasons why there is so much variation in the quality of our walls, but we believe it is mostly due to the transient workforce that was utilised to build many of these structures. High school groups, short term volunteers, and so forth have built much of our campus. Lessons learned during one construction project were not always carried over to the next due to this lack of consistency. It resulted in a huge variety of quality and decisions were made that in reflection were not the best.

During our long evolution we have tried many different earth building methods, mixtures, materials, and tricks with varied success. For example, our previous wattle and daub methods used little bamboo wattle support meaning that the earth mixture didn’t have enough support and the walls ended up being a little wobbly. Now we have moved to weaving many bamboo strips between the uprights, spacing them about one half inch apart rather than a few inches. Our earth mixture has changed through the years as well, experimenting with the ratios of clay to sand, the additions of manure, different straws, and other materials that we were told would make the mix better. We went through a phase of adding manure to our earth mixes and applying a “poo schmer” as a plaster. Looking back the additions of manure possibly led to a weaker final mix and the schmer although an effective plaster was not ultimately what we wanted aesthetically. It has since proven difficult to remove in order to apply a finish that we actually want. We didn’t realize the importance of compressing the edges of your walls, which have resulted in cracks around the edges of our wattle and daub panels; or the importance of bridging between two different materials (eg. wood to be covered by earth).

Over the years there have been many different techniques used and we believe for the moment that we have developed the mixes, techniques, and materials that get the job done efficiently and create great looking walls and structures. Among other plastering projects the main one for this year is to re-plaster the Casucha inside and out, using a method called “poor man's” tadelakt on the inside and a sponge floated exterior. Stay tuned for pictures of the finish!

Ali O​