​Arches are a lot like Amal Clooney: Smart, well-put together, and began life in the Levant. Some of the first arches (as far as we know) were constructed around 2000 BC in Mesopotamia, and as anyone who has wandered round an old Roman ruin will tell you, an arched doorway is often the only thing remaining after an earthquake.
 
Arches work because any external pressure pushing inwards or downwards on the arch stones only serves to compress them tighter. But...before you leap up in arch-building excitement, there are a couple of points to etch onto your brain.
 
Before starting an earthbag arch remember...
1. Earthbag arch wedges need to be a bit wedge shaped, and must be jammed in tightly, otherwise the arch principle doesn’t work.
2. As the forces of the arch push down to the ground, the arch will push outward at the base. So, you need some decent ‘abutment’ (aka a good fat earthbag wall on either side of the arch to stop it pushing outwards).

Here’s how to make an earthbag arch, step by step
 
1. You need a mould or strong arch frame to lay your bags around. In our small arch, we were incorporating part of an organic tree trunk, so the arch wasn’t perfectly round. On a small arch this won’t matter, but a larger one needs more precision.

2. Attach a piece of string in the centre of the bottom of the arch. You use this to check the angle of your arch wedges.

​3. Make a wedge mould for your earthbag 'slices'. Stick your empty earthbag in the mould, fill it with clayey dirt, and tamp it firm until you have an earthbag the shape of a slice of brie.

​4. Arrange your bag wedges around the arch. Use the string to check they're lined up correctly. Remember, if your bags are not wedge-shaped but straight-edged, they’re not going to compress together. As you lay the bags, weave the barbed wire in and out of the wedges (see top photo). Make sure the wedges are tightly jammed together.

5. Once all the earthbag wedge pieces have been jammed in, time to drop the keystone in the middle. It may end up being more of a squeeze and shove than a drop, but as long as you've jammed the keystone piece in nice and tight, it will hold.

6. Run a course or two of barbed wire over the top of the arch, and lay another layer of flat bags over the top of the arch to lock it all in.

Extra note from the Costa Rican Earthbag Team
 
Our Costa Rican team in The Mud Home FB group made the wide and beautiful earthbag arch in the top photo. Because of the span, I asked Murat if their arch technique had differed from mine in any way. “At the core, our method was the same, but we interwound/integrated a lot more barbed wire and aimed for super symmetry just because of structural demands,” Murat said. He also drove in a bunch of rebar just to make sure the whole thing was pinned together invincibly.

​Far up north, there’s a bard in the woods creating dream worlds for himself out of timber and earthbags. He’s built a cabin, a yurt and a hobbit house in his quest to escape the drudge of the wage economy. Let me introduce the free spirit that is Hugh Morshead.

“Ten years ago, I moved into a one-room cabin in the woods. I thought that I would be living a life of voluntary simplicity with one boot in the 19th century and the other in the  21st,” Hugh explained to me. “After my first summer the bank called. The manager met me at the door and asked if she could sit in on the meeting. Across the desk I faced two sets of arched eyebrows. Their concern was my sudden wealth...I paraphrased the money lender in David Copperfield – disposable income equals income minus expenses.”
 
Disposable income equals income minus expenses. Stick that on a billboard, someone! Whenever I read all these ludicrous “How to earn a million bucks” stories, I’m prone to chuckle or sigh depending on my mood. Yeah, earn a million and spend 900,000 in the process, not to mention selling your soul, your health and your peace of mind. Hugh’s philosophy is mine. Reduce your expenses, love the Earth and her creatures, tell stories and create beauty.
 
Now, I’m not going to recount Hugh’s tale, because he’s written that himself and will do a far better job than I. But I’ll whet your appetites with a summary.

Born in Ireland in 1953, and having spent most of his twenties backpacking, I think we can safely say Hugh has always possessed a touch of wanderlust. He emigrated to Canada in 1980 to build equestrian cross-country courses, and for 30 years ran a horse farm with his wife.
 
Then ten years ago they divorced.
 
I always think wherever you are in the world, divorce is poorly treated. There are no proper ceremonies or celebrations, because the staid judgement of society is that a divorce is some kind of failure. I would very much question that idea. Divorces are major successes, they are the victory of the individual soul over the expectations of the herd and the temptations of the comfort zone. They are beginnings, the time to dust off old dreams and live them to the full.
 
Thoreau
So, in true Thoreau style, Hugh left his old world and moved into a 150 year old log cabin on a spacious property in the woods in Ontario. “I went on a crazy building spree – sauna, earthbag hobbit house, yurt, greenhouses, gardens, root cellar, sheds, ponds,” he says. Thus began his new life. “I divided the year into three: reading and writing in winter, working and building during the summer and travel by bicycle or on foot in the autumn.” Now if that doesn’t make you consider going it alone, I don’t know what will. :)

 One earthbag house after another
Then somewhat later, ‘on a whim’ as he describes it, Hugh built an earthbag house for himself. It cost him just $500 to construct, and was semi-submerged beneath the ground. He lived in it for a year, and described the experience as much of a spiritual journey as a physical one.
 
The thing with mud homes is they are as infectious as smallpox, so naturally earthbag building didn’t end buried in the woods for Hugh. “My neighbour had a similar whim,” he says, “so I built one for her. Then I got a call to go to Australia for a month and build one for indigenous women elders.”
 
I always think building with mud takes you places you never thought you’d go. The dirt opens doors and paves new ways. So off Hugh trotted halfway round the world, from the northern cool of Canada to the Pacific heat of Australia, to build yet another earthbag dwelling for The Sacred Womyn’s Camp near Byron Bay. “It is a collection of tents in the bush...home to Lois Cook, the eldest surviving member of the local aboriginal tribe and designated as Custodian of Country.”
 
That story of Hugh’s experience with the Sacred Womyn’s Camp is a beautiful one that he recounts in his book, which will be available soon.

Which shelter is best?
Having built a variety of sustainable shelters, I asked Hugh which kind of structure he preferred and why. “I believe earthbag building is simply the best form of owner-build home for any environment,” he says. “Yurts are a perfect starter home or guest house, and combined with an earth plaster wall they have great potential – less work, less materials and easily built by one person.”
 
Why do we love earthbag?
I’ve often noticed that people are smitten by earthbag. I am too, still. It’s so simple and solid a technique, and so so sustainable, because in the right climate you can actually get away with zero timber. It’s solid, earthquake and hurricane proof, fireproof, bulletproof and soundproof. You can create gorgeous organic shapes with earthbag, too.

Community Spirit
 As you may have already gleaned, despite his appetite from freedom, Hugh is incredibly socially-minded. He is involved in his community through public speaking, a farmer’s market, and workshops. While the workshops are open to all, the emphasis is to empower women and indigenous people to build their own ultra-low-cost homes.
 
This summer he’s at it again. He will be up to his knees in dirt in a workshop in Canada organized by an indigenous Elder, Becky BigCanoe who lives on Georgia Island on Lake Simcoe in Ontario, Canada. The course will take place on indigenous land and the plan is to build a hobbit house and a yurt over a few weekends in July and August. I’ll be posting details of it in the newsletter when it’s finalised, but heck if I were in Canada, I’d go!

Hugh is very helpful and sociable. "I'm always available to answer questions," he says. You can read more about his lifestyle and building projects, or contact him from his blog: http://hughmorshead.blogspot.com/

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​Many people are planning and researching at the moment. January does that to people. If it’s natural homes you’re thinking of then here’s a comparison of a few building techniques you might be considering: earthbag, cob, straw bale, wood, stone, and wattle and daub. I've compared the cost, difficulty of technique, how the buildings fare in extreme weather, heating, and other advantages and disadvantages. This list was written with beginners in mind, so I hope it’s helpful.

Earthbag

Difficulty of Technique
Earthbag is labour-intensive compared to straw bale or wood, but the good news is the technique is fairly idiot-proof. Earthbag homes can be built fast, depending on the energy and organisation of the team. Finishing the interior may take longer though.

Cost
If you’re building a round house, the materials are very inexpensive. Mud is free. The sacks are inexpensive. Labour is the key factor for cost with earthbag, so if you have volunteers it’s going to reduce the price tag significantly. If you’re making a straight-walled post and beam structure, then it’s going to be more expensive.

Insulation
Poor. R 0.2 per inch (still better than concrete though).

Thermal Mass*
Excellent.

Shape
One of the attractions of earthbag is the freedom of design. Domes, circles, and wavy lines are all possible.

Earthquakes and Extreme Weather
Earthbag is without a doubt the strongest sustainable building technique out there. It has exceeded earthquake test limits with no visible damage. This is why it has become popular in seismic areas like Nepal. I can personally attest earthbag also performs amazingly in hurricanes.

In the Wet
Earthbag performs better in the wet than any other mud building technique because the bags and wire hold the dirt together in case of a flood. Again, as with all mud buildings, rubble trench foundations, a good stem wall and wide eaves are necessary.

Maintenance
Negligible. Plaster touch-ups, that’s it.

Longevity
Because it’s a modern technique we’re yet to see how long earthbag lasts. But with decent rubble trench foundations, it’s estimated to stand at least a century.

Other Advantages
Fireproof, soundproof, bulletproof. Earthbag is the survivalists’ dream:)

Other Issues
In mixed (wet followed by dry) climates, the clayey earth in the bags will swell and shrink, especially in the first year. This can put pressure on door and window frames, as the walls expand, compress the frames and then contract again.
 
Cob

Difficulty of Technique
Cob can be time-consuming depending on the climate, as each layer needs to dry before laying the next. Patience and some know-how are necessary. It’s a beautifully simple technique though. Perfect for artists, and fun too.
 
Cost
Mud is free. Labour, time and learning the art is where you could spend money. A great technique if you can find volunteers and have no pressing time limit.
 
Insulation
Poor. R 0.2 per inch (better than concrete)
 
Thermal Mass
Yes.
 
Shape
The beauty of cob is you can create all kinds of wiggly, organic shapes with it.
 
Earthquakes and Extreme Weather
Cob is stronger than poorly constructed concrete or brick, but not so great in floods.
 
In the Wet
It all depends on how high your footings are, and how wide your eaves. Cob can resist a fair amount of rain and weathering, but is not recommended on flood plains.
 
In the Cold
Earthen walls work well with passive solar construction, and heat up like a battery. But they are not recommended in climates that are subzero for months on end (for more detail on that look here).
 
Maintenance
Easy and enjoyable. You’ll probably just be patching up the final layer or the lime wash in the areas that see hard rain.
 
Longevity
Centuries. Cob houses have been standing for centuries in the UK.
 
Straw Bale

​Difficulty of Technique
Straw bale is one of the fastest and least labour-intensive of all the natural builds. Bales are light compared to sacks filled with mud. You can have a house up in weeks. Finishing the interior may take longer though, and you’ll need some basic carpentry skills for a post-and-beam structure.
 
Cost
Usually pricier than mud building because of the post and beam structure. If you don’t have straw bales to hand this will also add to the cost.
 
Insulation
Excellent. R1.5 - 2.5 per inch depending on which study you follow. The way to go in cold climates.
 
Thermal Mass
Poor.
 
Shape
Although there are plenty of examples of alternative shapes created from straw bales, you are using a rectangular building block which lends itself better to straight lines when compared to cob or earthbag.
 
Earthquakes
Excellent. Straw bale has been known to survive an 82-ton force on a shake table.
 
In the Wet
Moisture is the enemy of straw bale, and I’ve seen a few cases of bale rot now, which can be the end of your house if you’re not careful. Yes experts know how to mitigate this, and if you construct a decent rubble trench foundation, a high stem wall and wide eaves, straw bale can stand plenty of rain. But if you’re a newbie, you need to bear this tendency to rot in mind.
 
Maintenance
Plaster touch-ups. Usually easy and enjoyable.
 
Longevity
With the correct foundations and moisture/fire protection, straw bale can last a lifetime.
 
Other Advantages
Soundproof. Very snug.
 
Other Issues
- We’ve seen a number of fires in straw bale homes (Both Simon Dale’s went up in flames), so you really need to be super careful about your wiring, wood burner pipe exits, and so on.
- Mice can move into the walls if they find a hole to enter by.

Wooden Cabin

Difficulty of Technique
You will need some reasonable carpentry skills to build a nice cabin.
 
Cost
Wood is always the priciest material in a natural build, especially if you’re going for quality, so a wooden cabin will no doubt cost more than a straw bale hut, and definitely more than cob or earthbag.
 
Insulation
Very poor. You’ll have to add decent insulation to the walls in cold climates.
 
Thermal Mass
Poor. Wooden huts neither store much heat, nor prevent temperature exchange. This is one of their major disadvantages in my opinion.
 
Shape
Wood wants to go straight, so geometrical shapes are going to be the most logical for a wooden structure.
 
Earthquakes
Better than stone. Worse than earthbag or straw bale.
 
Hurricanes
How your hut stands up to a tornado does depend on how well built it is, but generally? Rather you than me.
 
In the Wet
Raised wooden structures will survive the wet quite well. You can stick them on stilts, for example.
 
Maintenance
Grrr. I find wood a right pain in the backside to maintain (though it does depend on which wood you’re using, and the amount of weathering your hut will see). Usually you’ve got to prevent it from sun and rain damage, which is expensive and time consuming.
 
Longevity
This largely depends on the wood you are using. Some quality hardwoods last forever. Others, like commonly used pine, will need a lot of care.
 
Other Advantages
Super fast to build. If you’re in a tight spot and need a roof over your head fast, wood can get you there.

Other Issues
Not soundproof, nor fireproof.
 
Stone House

Difficulty of Technique
You’ve got to know what you’re doing with stone, especially if you’re building with a natural mud or lime mortar.
 
Cost
If you’ve got the stone on site, and you are a stonemason, fantastic! If not...ouch! In most countries hiring a stone mason is going to set you back a pretty penny.
 
Insulation
Poor.
 
Thermal Mass
Good. Performs way better with mud or lime mortar than with Portland cement.
 
Shape
Ah, stone is very aesthetic in the right hands. You can create all kinds of shapes, round or geometric.
 
Earthquakes
Stone usually performs badly in earthquakes because the stones shudder and shift, thus loosening.
 
In the Wet
There’s no real issue with stone houses in the wet.
 
Maintenance
Very easy. Perhaps a bit of mortar pointing every few years?
 
Longevity
With the correct foundations and drainage, stone houses last millennia.
 
Other Advantages
The stones have a personality, an it’s quite wonderful to live with them. Another great thing about stone wall is that mice can’t chew through them.
 
Wattle and Daub

Difficulty of Technique
I think wattle and daub is quite underrated and underused in the trendier world of natural building. It’s not horribly complex. You will need some basic carpentry skills for the post-and-beam structure (much like with straw bale), but the wattling and daubing itself is wonderfully easy, and enjoyable.
 
Cost
Similar to straw bale in terms of materials. The post-and-beam structure is where the money goes.
 
Insulation
Poor.
 
Thermal Mass
Good.
 
Shape
Geometric shapes are best for wattle and daub, as the laths are straight lines.
 
Earthquakes
Not sure. I only know them from the UK where there are all but no quakes. If you know, feel free to add in the comments, and I’ll update the post.
 
In the Wet
As with the other mud builds, if you have decent eaves and decent rubble trench foundations with a good stem wall, wattle and daub can cope well in the rain.
 
Maintenance
If lime washed, then the maintenance is pretty straight forward.
 
Longevity
Excellent. Wattle and daub houses from the 15th century are still very much alive and well in the UK.
 
Other related articles:
1. Can you build mud houses in cold climates:
http://www.themudhome.com/mudbuilding/can-you-build-mud-houses-in-cold-climates
2. Mud Building Techniques Overview
http://www.themudhome.com/mudbuilding/mud-building-techniques-overview
3. Getting to Know Cob (Oliver Goshey)
https://www.abundantedge.com/articles-1/2016/5/24/cob-getting-to-know-one-of-constructions-most-ancient-and-versatile-materials

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The type of roof you choose for an earthbag house is important. No matter whether you construct a circular house or a rectangular one, you want to take into account your roof before you build (or be prepared to alter your roof style at the end).

I won’t deny it. When it came to my earthbag roof, as is so often the case with me, I skidded to success by the seat of my pants. It was sheer luck I chose the right type.

Roofing structures exert a lot of pressure onto earthbag walls. This is fine if the pressure is in the right direction because earthbag walls are strong. What you want is the pressure exerted downwards. What you don’t want is it pushing outwards.

The safest roof type for earthbag
If you are a beginner, the safest, most foolproof roof to stick on your earthbag house is a flat or skillion (pitched) roof, utilising horizontal joists running the length of the building. The joists act as a type of grid that pulls the structure together and prevents the walls falling outwards. What’s more, if you’ve built a smallish round house, you won’t even need a bond beam! You could top the joists with a number of materials: Corrugated iron, ply/strand board with a membrane. Any weight on the roof will be distributed by the joists and easily supported by the earthbag walls. The pressure exerted by such a roof is downward.

The link below shows another example of an alternative reciprocal roof on an earthbag house. Notice how this team combined two styles here. While the main structure is reciprocal, a web of rafters has been inserted into each facet of the roof. Those rafters then form the all-important grid through the top of the earthbag wall which locks the whole structure together.
http://mylittlehomestead.com/ep12-undergound-earth-bag-construction-reciprocal-roof-facia-frame-complete.html

Why you don’t want a compression roof
Compression roofs are typically used for yurts. The design of a compression roof means the strength of the roof structure is derived from the compression between an outer ring or wall, and an inner ring. Such a roof is exerting a lot of outward pressure on your earthbag walls.

If you know what you’re doing, there are of course a whole gamut of other wacky and exciting options for earthbag house roofs, and you'll be able to customize many to work for earthbag. But presumably, if you know all about roof construction, you're not reading this post.

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Remember Gautam and Kim from our crazy earthbag house in 7 days adventure?
Only eighteen months on from that workshop, and these two are already well into constructing an earthbag empire over in India. They have completed their first earthbag house, as well as planting 350 fruit, flowering, and indigenous trees to create a diverse food forest, and a vegetable garden too. But the project wasn’t without its challenges. I’m so grateful to Gautam for letting me share his experience, because it’s rammed full of great lessons.

​What Gautam posted in our Facebook Group:
​
“I’m happy to say my first earthbag structure endured its first torrential monsoons. We witnessed over 3m of rain. I have attached a video taken after a storm (over 13 inches of rain in 24 hours!) where most of the land is flooded, and with the rubble trench foundation working like a charm keeping the interior bone dry.”

Fantastic work Gautam and Kim! The rubble trench foundation combined with gravel bag stem wall is THE way to deal with earthbag buildings in wet climates. I’ve suffered various disbelievers regarding the amount of flooding an earthbag house can withstand, but a properly built earthbag house with the right footings can literally handle a monsoon. Had Gautam followed mainstream building advice and used concrete instead of gravel, I guarantee that water would have wicked up the earthbag walls.

But of course, it hasn’t all been plain sailing.

“Lime plaster on the other hand has been tricky for me. The first time we completed the lime plaster was about two months before the monsoons and it seemed to hold up well initially…till it didn’t, with chunks falling off from sections of the wall….On the plus side, there are certain portions where the plaster is rock hard and no touch ups have been ever needed.”
​
Agh plaster! I always say it’s the most difficult part to master. And in a wet climate? Really tricky. After a little further investigation and some more photos, I could see Gautam’s plaster was holding up fine on the stem wall. This was because it was gravel. I realised Gautam and Kim were having the same trouble I had had with my earthbag house, but on a more intense scale. 

What was happening?

Gautam and Kim’s earth’s composition was a staggering 50% clay! Normally you’d want around 20-25% clay in your earthbag mixture. In a dry climate it wouldn’t really matter. But in the wet? Clay swells when it gets wet, and shrinks when it dries. The clay inside Gautam and Kim’s earthbags was expanding like mad in the monsoon, and then shrinking back in the dry season. Lime plaster on the other hand doesn’t swell or shrink. So when the earthbags expanded, the lime plaster cracked. Had they used concrete, the result would have been exactly the same for exactly the same reason.

What can be done?  

​I found with my own earthbag house that it took a full dry season for the entire structure to completely dry out. Once the earthbags had dried thoroughly, I plastered again at the beginning of the next dry season, to give the plaster a good five months of baking before winter arrived.
​
My plaster wasn’t simple lime render though. It was clay/sand/lime/straw. 

What will Gautam and Kim do?

There will be some trial and error. I think they’ll probably need a clay/lime/sand plaster which is light on clay and heavier on sand. The lime will help rid the plaster of moisture when the monsoon hits, the clay in the mix gives a bit of flexibility to the plaster, and the sand gives the strength. It will, however, depend on Gautam’s clay as to how well it works with the lime.

The Next House

Oh, once the natural building bug gets its teeth into you, it doesn’t let go! Gautam is already laying the foundations for his next earthbag house.
​
“We just finished the stem wall for another 6m diameter roundhouse using local laterite rock with a lime mortar. We will be starting on the earthbag walls soon and I was wondering if lime should be used to stabilize the earthbags considering the plaster issues with the other structure.”

This, in my opinion, is an excellent idea. Normally you’d use 10-20% lime in stabilised earthbags, but in Gautam’s case, I think I’d go 30% and try and get rid of as much of that clay as I could.

Gautam has plans for a living roof on the top of this house. I can’t think of a better climate for it, and I look forward to seeing the result.

Lessons Learned

Now, if there’s a man who does a job well, it’s Gautam. He researched this mission carefully, worked out the best structure for his climate and location, asked for help when necessary, and got his hands dirty in live courses. As I think is pretty clear from the outcome, he really knows his stuff. Yet he still faced challenges.

So...if you take one thing away from this build, I hope it’s this: even if you’re an expert, you’re going to be greeted by something that doesn’t go to plan. The folk who manifest mud worlds are not those who don’t have problems, they are those who face them, and work patiently and persistently to overcome them.

You have read this post thanks to The Mud Home Sustainers and all those supporting this site, be it with contributions, positive and constructive feedback, or by sharing. If you’d like to join our Mud Home group and enjoy the perks that come with it, hop over to my Patreon page.

​Normally, earthbags are filled with damp earth. The earth should have about 20-25% clay in it. If you are using bags rather than tubes, then you first fill the bottom of the bag and squash the damp dirt into the base and corners to create a nice square bottom. After that you fill the rest of the bag, and lay it on your wall. When all the bags in the row are laid, you tamp the entire layer with something heavy and flat. Tamping is key. It squashes the clayey dirt into a compacted, immovable layer. Eventually, when the house dries, that dirt becomes a solid clay brick. 

All of the above is pretty time consuming, and dragging bags full of damp dirt around is hard work. Under normal circumstances, and to prevent a hernia, once the wall gets higher you begin filling the bags on the wall itself. Again, this is pretty slow going, and can drive impatient types like me mad.

I say, there’s always another way. :) Last year in my earthbag workshop in Turkey, we stumbled upon a brand new technique, altogether by accident, and it changed our earthbag world. You know how it is; someone makes a mistake, and it ends up being the best thing that happened.
 
The mistake was that a few volunteers threw a row of earthbags onto the wall without dampening the earth first. As I went round and prodded the bags, I could feel they were bone dry. Just a bunch of loose aggregate. You can read why you don’t want loose aggregate here.
 
Now...there is a common misconception that the polypropylene bags usually used for earthbagging aren’t breathable. This isn’t correct. They are definitely breathable and permeable. If they weren’t, your dirt wall would never dry out properly. So, knowing this, I decided to try and wet the bags on the wall (well, actually I decided someone else would wet the bags, but you know what I mean).
 
A kind helper grabbed a hose and gave the dry layer of bags a really good soaking. Then he grabbed the tamper and tamped the lot down. When I checked the bags, they were as good as the rest. The bags had absorbed the water, and the tamping had distributed the water evenly through the earthbag.

The advantage of wetting the bags on the wall is that you don’t have to cart all that damp earth about, nor do you have to dampen the earth on the ground and mix it in (which is a bit of a bind in itself). It is a lot lot easier to work with the loose dirt, and easier to fill the sacks, too. 

1. Make sure your clay is distributed evenly into your dirt.
2. Fill your earthbags with dry soil.
3. Lay them on the wall.
4. Take a hose and give the whole layer a thorough wetting. Make sure all the bags are well dampened.
5. If you’re using individual bags, go around and check the corners of the bags are nice and tight, and not sticking out. Reshape and regusset them where necessary.
6. Tamp the whole layer.
 
Note: This technique only works by dampening one layer of bags at a time. Don’t throw a whole house up and then think you can squirt a hose on it. It won’t work.

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Earthbag building is probably one of the least technically taxing construction techniques you can choose. You can get away with having no experience whatsoever and still build yourself a strong, sound home. That said, I have seen a few examples of things going wrong, and it’s always the same mistake, so I thought I’d shine a spotlight on it.
 
Everyone worries about the wrong thing, and I was exactly the same. Most questions come to me concerning foundations, climatic impact on earthbags, and bag fillings. This is probably because folk are at the outset of their build and still planning. Once the construction begins, the questions tend to evaporate in the excitement.

​The bag filling is not nearly as crucial as you think it is.  As long as you’re using dirt, and that dirt is basically sticking together when wet, you’re going to be fine, (see my article on bag fillings). I did recently spot some birdbrained article by someone who had clearly never laid a finger on an earthbag, claiming you put straw in the bags. Obviously that would be a bad idea. Earthbags are for clayey earth.
 
The foundations
Now I’m not saying you don’t need to think about foundations. You do. But we’re all somewhat brainwashed by mainstream building techniques, and convinced the foundations are the linchpin preventing the house from falling down. We’re also certain that that there has to be a concrete slab somewhere, because that’s strong, right?
 
In fact, a whole bunch of things contribute to the structural integrity of a house. With earthbag building, the foundation is as important for drainage as it is for structural strength. Forget the concrete slab. Forget concrete full stop. It really isn’t what you want or need. Make yourself a nice simple rubble trench with a couple of earthbag rows below grade, and you’ll be fine. It’s simple, effective, and hard to screw up.

​The most common mistake is for a wall to collapse.
The most common earthbag issue by far is for a wall to topple. This notably only happens with square/rectangular structures or very large round structures (more than 10m diameter), or retaining walls. So if you’re new to the bagging game, you might want to consider a smaller round house first.
 
If you’re adamant you want straight walls, then you’ve got to pay good attention to a few things:
1. You need buttresses. And the buttresses must lock into the wall and be attached to the barbed wire of each layer. So you can’t just say, “Oops maybe I need a buttress here,” and add one at the end. It has to be incorporated into the build. This equally true for retaining walls. The higher the wall, the more buttresses you need. A rule of thumb is a maximum of 10 feet/3 metres between buttresses.
 
2.Your vertical straightness is crucial. With a small round house you can get away with an awful lot. With a square/rectangle, those walls need to be vertical.
 
3. You need a decent bond beam* to lock the top of the structure together, and on a square structure, that would mean long, straight planks of wood nailed into the top layer of bags.

​Every building technique has its own logic, and its own way of supporting itself. With earthbags, the structural strength of the building is created by the ‘tying’ together of everything within the structure using barbed wire. Everything – every bag, every window frame, every door frame, every arch and buttress – must be attached to the rings of barbed wire so that the entire structure is interlocked. This is what really gives it the tensile strength when under pressure of impact or earthquakes, and what stops the walls from toppling over.
 
If you want to assess whether your walls are liable to collapse, climb on the top of them or give them a shove. If there’s any swaying, you’re in trouble.
 
Finally, at the end of the build, make sure you have two layers of earthbags going over the top of everything (lintels, arches etc.) Those final two layers create enough pressure and tension to hold the structure together. In most cases you will also add a bond beam* here too.

​I know some people are using mesh bags, and I have to be honest, I don’t see how the structural integrity of the building is maintained, especially in seismic areas where the house sways. If someone has actual hard-won experience (rather than hearsay or armchair opinion) of using the mesh bags, please add your findings in the comments below.
 
*A bond beam is a horizontal reinforcement that runs along the top (or sometimes the middle) of a wall. It holds the wall together and stops it breaking open. In modern mainstream construction, concrete and rebar are used. In traditional building it has usually been thick wooden planks or beams. Don’t assume concrete is stronger. It is brittle, and in the case of an earthquake it can crack. The rebar is the only thing giving concrete any strength. In my opinion, for an earthbag structure, wood is a better option. It has more give, and can move with the house in the case of a quake.

​If you want to know more about the kinds of mistake you can make while building an earthbag house, you may be interested in my most popular book, Mud Ball. This is the story of how I built my own earthbag house, and the various agonies I and the victims I managed to lure into helping me, endured in the process. The ebook is on offer this week at $3.99 on all ebook retailers in all locations (including Kindle, Nook and ibook) so if you’d like to catch it at this lower price, now is your chance. It will go back up to $5.99 on 24th December 2017.

“Despite having very little money, almost no building experience, and endless naysayers who told her she would fail, Atulya K. Bingham completed her lovely earthbag home . . .Her personal, inspirational story shows how anyone can build their own sustainable home with earthbags." Dr. Owen Geiger, author of Earthbag Building Guide and the Natural Building Blog. 

Many thanks to Baykal for keeping track of the figures for us.