​Domes have been an integral part of human construction for a long, long while. From the mosques of Istanbul to the basilicas of Rome or Moscow, from adobe vaults in Mexico to the snow igloos of the Arctic Circle, the curved roof can be found in an awful lot of places. So that must mean it’s great, right?
 
Hmm. There’s a lot to like about the dome. There’s a lot to be wary of, too. And there’s a very good reason it was only the Inuit of certain areas who built igloo snow domes. Others further south used other techniques. It's not just coincidence that the mud dome was traditionally built in places like Cameroon or Mexico, but not in Cornwall or Galicia. Dreaming of a mud Sistine Chapel in your back garden? Read on.

The dome became something of an architectural darling in the ’60s. A lot of this has to do with Buckminster Fuller, who began pioneering geodesic dome structures and biospheres in the ’40s and ’50s. A decade later domes became popular on a more individual homeowner level, when space-age architecture became trendy. This is also when the limitations of the dome as a house became clear.

The Good
Domes are beautiful for sure, and they feel extremely calming to live inside. They are like wombs or caves. And heck, for an artist they're both original and funky. With their soft lines and circular form they soothe both eye and spirit. But beware, like most sexy things, they come with some potentially costly drawbacks.
 
The Bad
Lloyd Kahn of The Shelter Blog wrote two books on domes. They were his most popular and lucrative publications. Yet he pulled them off the market because, to quote him, they were “smart but not wise”. Here’s a list of reasons why:
 
1. Impractical
One interesting issue Lloyd Kahn has with domes is that they are impractical. You can’t dissect them easily into sub-quarters, meaning they’re great for meditation centres or lecture halls, but not so great for a house, where you might want to cut the space up into separate rooms.
 
Solution: Well, I suppose here I’d say if everything had to just be practical in this life, I’d probably hang myself from boredom. That isn’t to say Lloyd doesn’t have a good point. I experienced the same issue on a lesser scale with my roundhouse. Pretty much all building materials are designed for squares. And you’re probably going to be making your own furniture if you go dome. But as far as the separate rooms are concerned, if your heart is set on round then the solution is to build multiple smaller round spaces that are linked, like Rhonda did here in Mexico.

2. Leaking
One of the more serious disadvantages of the dome is they are notoriously difficult to waterproof, because unlike most housing structures, there's no roof, and therefore no 'hat' to protect the structure. This is fine in a desert, and even more fine if you only have soft powdery snow sitting on ice blocks. But bring in some serious rainfall, and you’ve got major problems. For the geodesic domes there are masses of joints where the triangular panes all tessellate, all of which are potential leak points. That’s a lot of sealant you’re going to need, and a lot of potential maintenance.
 
For mud domes, in particular earthbag domes, water-protecting is the thing you absolutely have to wrap your head around. Because what you really don’t want to do is what every mainstream builder will tell you to do, namely coat it in Portland cement.
 
Don’t cement over a mud dome!
If you slap Portland on, you have basically stuck an impermeable crust over your lovely breathable walls. So you’ve just killed the airflow. Boom! This will lead to an increase in mould and damp. The house won't be as cool in summer (or warm in winter) as it would have been if it were all mud.

Also, there’s a reasonable chance the cement will crack and fall off too, as clay walls expand and contract with humidity changes, while Portland can’t. See this experience kindly shared by Gautam. Please note this was lime render not Portland, but basically it's the same issue (though at least the lime render will breathe). http://www.themudhome.com/.../gautam-and-kims-earthbag..

Proper solutions:
There are two main ways to keep a dome dry:
 
1) Do what Jehane Rucquoi did at 3 Moons and build a deck on it, or add some sort of cap over the top. This is easily the best way to protect the dome. Jehane's design was ace if you ask me.
 
2) Use shingles. See more about them here: https://en.wikipedia.org/wiki/Roof_shingle
 
Yes, domes are a tough one. But I'm not going to lie, I'll probably make one before I die, because for a creative soul they are beguiling structures.

Related links:
 
Kelly Hart’s interview with Oliver Goshey, all about earthbag domes. A must-listen if you are considering building one! https://abundantedge.com/abundantedge-xzmogh2g479mqg866e0v765lb804l6
 
Lloyd Kahn interview, where he discussed the limitations of the dome: https://www.buildingsustainabilitypodcast.com/45-years-of-building-inspiration-lloyd-kahn/
 
Rhonda’s dome world in Mexico: http://www.themudhome.com/mudbuilding/rhondas-sculpted-earthbag-dome-home-in-mexico
 
Jehane’s earthbag domes in Nevada:
http://www.themudhome.com/mudbuilding/the-85-year-old-dome-builder-of-arizona
 
Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​It’s actually pretty easy to add window and door frames into earthbag buildings. The most important thing, as always with earthbag, is anchoring things to the walls. But there are a couple of potential issues, so it pays to be aware of them.
 
1. Making a mould
The standard way to create space for your door or window is to make a mould. Some people use tyres, some use hay bales, most build a box out of wood or ply and insert it onto the wall where they want their window. 

That said, I’ve never done it this way. I’ve always stuck the window or door frame straight into the wall, and built around it. There are pros and cons to both methods, as you’ll see in a bit.

2. Anchors
As you lay earthbags up to the edges of the mould or frame, it’s crucial to add anchors between the bags that you will attach your frames to. What you don’t want in any kind of construction is the frames shifting or sliding about. They need to be securely nailed into the earthbag wall. How?
 
You can either make your own anchors from small planks of wood and slot them between the bags like this:

Or you can use metal brackets to do the same job (see Owen Geiger’s method).
 
3. Fixing anchors onto earthbags
Fix the anchor onto your earthbag by driving big fat nails (minimum 10 - 12cm) right through the anchor and into the earthbag.

​I’ve found you want one anchor, every three or four rows of earth bags. Any less and things start wobbling.
 
4. Barbed wire
Once your anchors are secured, you lay the barbed wire over the top of the anchors, and nail it into place. This gives the upper row of bags something to grip onto. Once you tamp the lot down, that anchor is wedged. Now you have something to screw/nail your window or door frame into.

​Issues to watch out for:
The snag with earthbag is this: The higher up you go and the more you tamp, the more pressure is exerted on the lower bags. So they will naturally squeeze inwards, pressing against your window or door frame, or indeed your mould. If you are using a mould this can make it difficult to yank out. The common recommendation is to stick wedges between the mould and the earthbag wall. Even so, most people still seem to find it hard to pull the mould out. A mould without rough edges will help your cause. Or perhaps a bit of plastic sheet between the wall and the mould would help it slide?

​If you want to add window or door frames directly into the wall, your issue is this: Your frames must be tough or they will buckle under the pressure of the bags. This happened on my first house, where the window frames turned into trapeziums :)) You need to pay attention that your lower, upper and side lintels are heavy-duty, because they all bear the brunt of the pressure. We used 10 x 30 cm lintels on the build in Olympos, and they held up.
 

Good luck folks! And remember, everything has to be anchored together in earthbag building. If it's not anchored into your wall, it's not secure and may well wobble.

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​Starting Your Own Project?
The Mud Home small, private and very supportive Facebook group is a safe space for new mud builders and off-gridders. It’s also the most inexpensive way to get assistance from me. It’s filling up, though. The number of members will be capped at 100 so I can give everyone the proper help they need, so if you want to be part of it, don't leave it too long.

​ (With details of how Cath made her super living roof)
 
Time for a different earthbag build. I’m letting you in on a mud adventure that has touched my heart rather. It’s one you won’t have seen before. Deep in the urban badlands of Brixton is a mud home with spirit. It’s plucky, original, and despite its size has plenty of personality – much like the woman who built it, in fact. Welcome to Mud Hut, built by Cath Coffey and the Mud Hutters.

For those outside the UK or who don’t know, Brixton isn’t some rural off-grid wilderness, it’s London. But while Mud Hut squats in the capital’s backyard, it harks back to somewhere else, somewhere much further south. Its roots stretch right back across Europe, over the Mediterranean, through the Sahara, and into East Africa.

“I always loved visiting my grandparents in Kenya,” Cath told me. “They lived in mud huts in a village on the foothills of Mount Kenya. My grandfather had two wives, each with their own hut, thatched with reeds from the river. Kids, goats, chickens and wood-fired cooking smells all intermingled. The sound of Kikuyu and laughter...It felt like a free life, if a strenuous one. They grew their own food, and were mostly self-sustaining.”
 
And it was this Kenyan life and family that inspired Mud Hut.

Mud Hut is 22 feet in diameter. It’s an earthbag house (hyperadobe) with rubble trench foundation, earth plaster, and wooden floor. The house was made with raschel mesh tubing, which Cath found from a certain Mr Jing Hou in China. “He was the only person I found who would send me a small quantity (500 metres),” explains Cath. “I still have plenty enough left for another structure or two! Mr Jing Hou loves the building...calls me Mr Cath.”  :)

How long did it take to build?
“The house took just over a year to build, and that includes a long break for winter. It was constructed by myself and one other helper mainly. Del McCoy was my main wingman. The rest of the family were also amazing, each in their own way. I’ll always be indebted to friends who took time from their busy lives to help. It was a very special time,” explains Cath.
 
How much did the house cost?
“Honestly, I don’t know and I’m scared to total it up! I know it cost a lot more than I thought...scrub that...I didn’t think about the cost. I just had a compulsion to build.”

​How to reduce the cost of your build
On the subject of cost, one thing I can say is that Cath is super smart about reducing building costs by using recycled and reclaimed materials. It makes a huge difference. I often think that with building as with travelling, you spend as much as you have. Do take note of Cath’s tips on foraging below, especially if you are in a first-world country where people shamelessly throw everything away.
 
How Cath made the living roof
Living roofs are always made like massive club sandwiches: there are plenty of layers. Cath really did her homework when it came to the roof. It’s designed for a cold, wet British climate.
 
1. The roof has a wooden frame (60% off from a family member who worked at a large DIY store).
2. The frame was covered with free reclaimed 18 mm plywood.
3. Next layer was carpet from the bins at the back of Carpetland (pure wool!)
4. Then Cath added 6mm EPMD pondliner (expensive).
5. After that there’s a root barrier (root barriers are always non-organic, otherwise obviously roots will burrow and your roof will no longer be waterproof.)
6. Finally sedum modules with Leca (expanded clay balls) infill.
 
“I know from my sedum roof at home that the sedum will eventually migrate and colonise the Leca. The carpet, sedum and Leca all make for good insulation. There is also 150 mm insulation batting in between the roof joists. The building is both warm and cool when you need it to be. Result!”
 
The pitch of the roof
People sometimes get this wrong, because unlike tiles or other roof systems, living roofs don’t want too much pitch. If the roof’s too steep you’ve got erosion issues; if it’s too flat you’ve got a swimming pool. About 5 - 10 degrees is optimum (that’s 1:12 or 2:12 max).
 
What about the edging?
This is the trickiest part of the living roof, if you ask me. Cath’s living roof is edged with steel garden edging. The EPDM is sandwiched between two layers of edging so that excess water drips off the lower edge. She plans to build planters with water-loving plants at the drip edge to take advantage of the run-off.
 
This is definitely a super model for a living roof on an earthbag house in a wet climate, in my opinion.

​What was the most challenging part of the build for Cath?
“The doubt,” she replies. “The ‘do I know what I’m doing?’ The physical demands; earth is heavy. The protracted time period. Costs spiralling. The ups and downs of life.”
 
Mud Hut Today
Cath built this house for her artist sister, in fact. “She’s a compulsive maker and needed space.” And what a beautiful place for a creative to work within! It’s the ultimate she-shack.

​Cath’s Resources:
Cath has kindly shared the resources she used to build Mud Hut.
 

• The late great Owen Geiger of the Natural Building Institute. “So generous with his  responses,” Cath says.
• Earthbag Building by Kaki Hunter and Donald Kiffmeyer.
• YouTube: A valuable resource full of generous people sharing their experiences. Great for people who learn best by watching.
• The Mud Home and yours truly (blush).

 
On the subject of Owen Geiger I’ll also pay tribute, because he patiently answered my questions too, and whenever I’m feeling a little frustrated by my inbox, I always remember his generous example.

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​Hold on to your seats. I’m about to blow your mind. I’ve just witnessed the most stunning clay plaster I’ve ever seen. It’s on an earthbag house too, which I can tell you is one of the trickier substrates to achieve a decent finish on.
 
The masterpiece in question is courtesy of the wonderful Geeli Mitti community in northern India. Geeli Mitti was founded by Shagun Singh, who is pretty much as incredible as her houses. What she has created up there near Delhi is nothing short of a dream. 

​This earthbag house is the latest in a number of revolutionary architectural projects at Geeli Mitti. Shagun and friends love experimenting with different kinds of natural building, and have perfected clay plasters to such an extent, I’d rate it as some of the best out there. And that’s no exaggeration.
 
I’m a bit lucky because Shagun is a member of our private Facebook group, so I was able to get some details on how these colours and finishes were achieved. It’s all surprisingly simple.

​I originally assumed this was a clay paint finish, but I was wrong. “No paint used,” explained Shagun. “It's the finish plaster coat itself on the exterior. We used red clay soil dug out from a nearby land, and similarly some whitish-yellowish soil that had been dug out, then added some yellow oxide minerals to it to achieve the colour.”
 
Yes, amazingly and wonderfully, this beautiful result wasn’t achieved by importing a bunch of materials, but by searching out and using clays in and around the structure itself. This is so often possible. Unless you’re at the beach, it’s highly likely you have many different types of clay in your neighbourhood, and it’s worth hunting for them because you don’t need huge amounts for a finishing layer of plaster.

​“On the inside, we lime washed the walls with the yellow oxide added to lime,” says Shagun.

​But what about this truly eye-opening Shiva sculpture? How was that finish achieved?
It's actually a clay, sand, dung mixture sculpted into shape. Then, once the sculpture was completely dry, it was sanded smooth with sandpaper. After that it was coated in linseed oil for sheen, hardness and weather protection. Nice huh?

This guy is a real masterpiece. I wondered how Shagun and friends achieved the milky finish. “This finish plaster was a mix of our site soil which is 60% sand, some clay to balance it, cow dung and very little lime. The lime to rest ratio would be 1:6 and then once the plaster was still slightly moist, not completely dry, I burnished with crystals using small circular motions. So lots of elbow grease needed,” says Shagun.
 
As you see, the mixture itself is incredibly simple. It kind of proves why I’m skeptical about adding a million things to your earth plaster. The application technique, along with perseverance and  effort, is at least half of the story.

Over the course of time, some of the Geeli Mitti team have become real pros. "I'd love to mention the name of one of my oldest team members, Ganesh," says Shagun. "He has worked with me throughout on all the plasters and finishes showcased in the article, and has become quite the plaster wizard now!"

​If you think Geeli Mitti is content to rest on its laurels here, you’d be wrong. They’ve already got another ground-breaking project organised for the end of May. What’s next? A bamboo geodesic dome! So if you’re in northern India and want to experience the Geeli Mitti natural building phenomenon, I’d sign up for that course quick.
 
More about Geeli Mitti
You can find out more about Geeli Mitti from their Facebook page or their website: http://geelimitti.in/
Do check out “The Team” page on Geeli Mitti. I love that the animals are placed at the top of the team, and the cooks are second. Sounds exactly right:)

Are you building or planning to build?
If this is you, consider joining The Mud Home Facebook Group. It will no doubt save you a bunch of money, as many have already commented. You also have the chance to connect with some amazing natural builders and off-gridders. The numbers for that group will be limited to 100 so that I can give the proper attention to each project.

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​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.

Are you building or planning to build?
If this is you, consider joining The Mud Home Facebook Group. It will no doubt save you a bunch of money, as many have already commented. You also have the chance to connect with some amazing natural builders and off-gridders. The numbers for that group will be limited to 100 so that I can give the proper attention to each project.

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​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/

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.

​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.

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​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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If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.