How to use rubbish in cob building and more.
​There are so many facets to the “problem” of trash: building with it, reusing it, what about recycling? How to deal with garbage when you’re off-grid in nature? How to reduce it? Because heck, as a species we have a real problem with the stuff. As with all these environmental issues we also have piles of judgement that tower far higher than the actual garbage dumps themselves. It’s unhelpful because there’s no simple answer (other than stop buying stuff) and many many subtleties to consider.
 
Here’s what I’m doing with my rubbish. Roll on the judgement:) It’s complex, so stay alert.

1. Reuse/Recycle - Welcome to the Trashure Bin
 
We all know recycling isn’t the great eco-saviour it was supposed to be, as a lot of it ends up transported across the world to be dumped in another country. We also all know it would be better to reuse stuff. But how exactly can you manage that sensibly without your house turning into something you might see on Hoarders?
 
Here’s how I do it.

​I have two bins where I shove everything that I could ever possibly reuse, this includes jars, bottles, plastic containers, tins, sacks, plant pots, netting, blah-de-blah. I can’t tell you how many times I dip into those bins, and how often they save me buying something. Need something to put those nails and screws in? Go to the trashure bin. Need a water pot for the hens? Look in the trashure bin. Need a food container? You guessed it, I go to the trashure bin.
 
But...
 
How I keep the trashure in check
We’ve all seen those reports of someone lost in their hoarding habit, with sheds and rooms overflowing with stuff they’ll never use. It’s unhealthy and can end up polluting your beautiful land. So how do I stop my trashure from taking over?
 
Once the trashure bin is full, then it is time for stage two. I reuse an old sandbag and fill it with the least desirable bits of trashure. Those bits go to the recycling. I try to choose glass and tin because I know they have a much better chance of being recycled. I usually need to do this once every two months. No, it’s not perfect. Please show me something that is. Having said that, I'm always ready to improve, and the building with rubbish ideas at the end of this article are where I'd start.

Beware: While trash can be treasure, you might want to erect some defense against other guilt-ridden consumers who will be itching to offload their crap onto you like you're some local version of China. If you're like me you'll often be too quick to say yes, and then be stuck with something that pollutes your land. Be discerning with what you take from other people or your home ends up looking like a landfill site.
 
2. Compost it
If it’s food or organic, then obviously it goes on the compost heap.

​3. Burn it
This is the most controversial of the lot. I use a wood burner to heat my home so I burn all old papers and cardboard in it (actually they are my firelighters). My rubbish may as well keep me warm after all. But here’s the thing that causes the controversy: I also burn small bits of plastic. Huh? WHAT? Oh, the moral outrage! Yes... I shall roll up my sleeves on this one, because urbanite eco-purists haven’t got a flaming clue if you ask me.
 
If there are any tiny plastic pieces that I think will cause an animal harm, such as those stupid bits of plastic they tie stuff up with, or a bit of sellotape, or the scraps from a disintegrated plastic bag, namely anything an animal might swallow, I burn those. And I feel good about that decision. In my opinion the “toxic” gas caused by a finger’s worth of plastic a fortnight is a lot less harmful in the air than it is in solid form in multiple animals’ stomachs.

4. Build with it
One of my favourites of course. I reuse a lot of rubbish in building. Glass bottles and jars are the obvious one. I’ve used them all over my building work, creating windows in the chicken coop or bottle walls.
 
Kristen Krash of Sueño de Vida in Ecuador said she stuck lots of trash into the cob walls of her buildings. If you are remote it can be a real pain trying to get rid of rubbish, so it’s a fantastic plan. You can actually embed it into your cob work and make walls out of the stuff.
 
Here’s how Kristen uses rubbish in cob walls:
1. Stuff all the small pieces (bottle caps, wrappers, bags etc) into plastic bottles.
 
2. Then on top of the wall foundation (usually mortared stones) she lays a row of stuffed bottles. Then, a layer of cob, then more bottles, then cob.
 
3. She lets each double layer set up for a day in between to stabilise. "It's just like earthship walls, except with cob instead of cement,” she says, and adds that she also once worked on a cob house where the builder put an entire broken TV set into the wall.

Please note: You do need to pay attention to how you're impacting the structural integrity of your cob walls when using rubbish in them. Kristen used most of her rubbish in non-supporting walls.

​What did I do with the broken tiles from my roof? I used them as drainage and terracing.

Old cupboards, old doors, old windows etc can all be upcycled into beauty, as Dianne Gungor and Bismil have shown in their work.

Old Clothes
Ah well this is something most rural folk can feel good about. Compared to anyone working the 9-5 or participating in “society,” we off-gridsters don’t usually own big wardrobes. And everything is used until it basically doesn’t hold together anymore. Once it doesn’t hold together, we then cut it up and use it as cleaning cloths, rags, animal beds, etc etc. I can’t remember when I last threw out clothes other than shoes.
 
Reduce your shopping (forage, plunder, re-use, upcycle)
Obviously the best way to reduce your rubbish footprint (and your off-grid headache of getting rid of rubbish) is to stop buying stuff. Really, there isn’t such a thing as an eco-product. If it had to be made in a factory somewhere and/or transported, it’s not eco, so stop kidding yourself. If you live in the country this is so much easier. Every time you forage something be it hay, stones, wood, or clay, you’ve saved rubbish.
 
The worst offender? Get ready to be surprised...
The worst offenders, which are never discussed, are building materials. Even a natural builder like me who refuses to buy anything and builds out of mud and lime and anything she can find laying around, even so, my biggest non-recyclable rubbish contribution is building materials. Linseed oil tins, rollers, paint brushes, glue cartridges.
 
The other worst offender is of course plastic packaging. You can do a lot more about this one though by shopping in local markets, growing your own food, and not engaging in processed foods. Who wants to eat that plastic packaged poison anyway?
 
Other creative ideas from The Mud Home Facebook Group:
 
“I would turn it into art for your home and or garden. I think it's something to study and ponder at night on how to make creative garden totems, fun wall art, flying stuff, steampunk art,” says artist Daphne Roberts, who turns everything into beauty.
​
“Old cement goes in my own little landfill, trying to build up an area,” says Chris Mack in Ecuador. In fact, if you have a piece of land this is probably the most honest way of dealing with it. You’ll see how much crap you have, and you can always plunder it later.
 
“Cement renders and pointing can be crushed and used as aggregate in hydrated lime mortar, render, and plaster. And pulverized brick (resulting from damage caused by said cement renders and pointing) can be repurposed as pozzolan,” explains Claude, who’s naturally renovating an old house.

​Related link - Dianne and Bismil’s upcycled bathroom:
https://www.themudhome.com/mudbuilding/a-stylish-natural-bathroom-made-of-lime-and-milk
 
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Istanbul is famous for its spectacular domes, many of them commissioned by a well-known Sultan called Suleiman (The Magnificent)*, and realised by his favourite architect Mimar Sinan. None of them were earthbag of course. Until now.
 
Get ready folks, this is probably one of the most technically interesting earthbag structures I’ve seen, with some pioneering design features such as an oculus skylight and a slipstraw insulation envelope. Woohoo! Yes it’s ambitious, even so there’s a lot for everyone to learn from this project.
 
But first let me introduce you to Xavier Allard, the quiet French/Belgian chap with plenty of attention to detail who managed this project. Luckily for us he documented it extremely well too. But who is he? And why is he in Turkey?
 
“I discovered Turkey while traveling and decided to stay”, says Xavier. He’s not giving much away here eh? So I shall interpret this as meaning he rather liked the place, possibly because the food is fab, and the people are friendly? Anyway ten years on he’s still in there.

How did Xavier become the Mimar Sinan of natural building?
 “No no, I’m not Sinan, that’s Matthieu Pedergnana**”, explains Xavier. “I’m the builder. It all began when I met Matthieu in Ankara. He’s a French architect who was teaching architecture at Yaşar University...I learned everything on site both from him as a building mentor and on my own, first volunteering on alternative building projects, then organizing workshops myself. Eventually I specialized in woodworking”.
 
The Koluba Team
After a lot of natural building experience, Xavier set up his own natural building organisation called Koluba. The Koluba team have been making plenty of mud beauty over at the Sihirli Tohumlar*** permie farm about 130km from Istanbul. And it warms my heart to see earthen structures once again sprouting on Turkish soil. As you’ll no doubt remember when I built my earthbag house back in 2011, most people thought it was a pile of poop, that it would melt in the rain, and that concrete was God. Sigh.
 
Xavier also has a valuable partner in Koluba, Okan Demirbaş, a structural engineer specialising in plasters and stonework. “Okan is gifted with both a sharp practical mind, the ability to work fast and well, and a deep interest in true craftsmanship, a combination so uncommon that finding new team members is one of our main struggles these days”, says Xavier. Oh and I hear you!
 
So as you can see, we have a very well qualified and experienced team here. Good job too! This build is not for the faint of heart.

The Magnificent Earthbag Semi Dome
This stunning structure is 80m2, and it’s unusual because it’s an earthbag semi dome built within a wood/slipstraw structure. It has a reciprocal green roof, and comprises three rooms, two storage bays and a terrace. If you’re a beginner to earthbag, don’t try anything as ambitious or large as this. Koluba had a big team and a lot of expertise on their side.

The Foundations (A New Method)
Koluba did something unconventional with the foundations. Instead of the traditional rubble trench, they just used tamped gravel bags laid below grade as a foundation. “We did this a lot on small buildings”, said Xavier, “But this time it had to carry a lot of weight (the roof is 45tons+), and it managed successfully”.
 
This is very interesting news, and it makes sense, because the gravel bags act like a rubble trench anyway, and if they’re laid below grade, they should serve as footings just as well.
 
Post and Beam Structure
Next the team attached twenty 10 X 20cm posts onto the earthbags to carry the roof. How did they do that? The posts have anchors, or feet, on the bottom to increase the contact size, and then they were locked in by another layer of bags laid over the top.
 
The large roof beams that create the roof mandala rest on the posts, and they meet at the centre of the building to form a heptagon over the oculus of the dome. This is the awesome skylight, and it’s beautifully reminiscent to me of the Blue Mosque roof.

To see all this more clearly, watch the timelapse video.

The Slipstraw Insulating Envelope
For me this is one of the most brilliant parts of this building. We always hear how you can’t build earthbag in cold climates. But if you are in a cooler climate, and want to do earthbag, here’s a fantastic way to insulate your structure.
 
First, a series of wall panels were installed between the posts. Then they were filled with 20cm of slipstraw (straw with a small amount of liquid clay, compressed into temporary frameworks). Finally, the earthbag semi dome was built in the centre of that structure. Neat huh?

The Semi Dome
“The earthbag semi dome in the centre is 4m in diameter, 3m in height. It has 5 openings and is quite flat so we had to add buttresses in the rooms”, explains Xavier. Which brings up a point I’m eager to highlight. Plans always have to shift if you’re a pioneer builder, and you may have to add things you didn’t want to initially. But I tell you what, they always end up being some mighty useful or beautiful feature at some point, as you’ll see at the end.
 
The Roof
The roof beams are connected with about a hundred 10 x 20cm purlins. Then about 20cm depth of hemp chips were poured around them. After that wooden roofing boards were laid, then an EPDM waterproof membrane, and finally 25cm of soil for the living roof.
 
For more details you can see exactly how they did all that in this short but informative video: https://www.youtube.com/watch?v=AlgFqNyno6w

The Interior
There is a kitchen and a bathroom, and the dome serves as a living room.
 
The floors in the three rooms were insulated with hemp chips poured under a wooden floor. Everywhere else, the floor slabs were made with a mix of lime and LECAT (expanded clay) and those slabs were topped with stones.
 
The walls were rough plastered with an earth/sand/straw mix, then the interior walls were finished with clay plasters. The exterior was finished with a lime plaster. The bathroom is tadelakt. And all the furniture and trimming is handmade (beds, stairs, benches, shelves etc).

​Challenges
I always like to mention challenges in building, because there is a naive idea floating around the minds of those who haven’t actually built anything, that if you just plan and research and think about it enough, you’ll avoid all difficulty. You don’t get natural builders and architects more qualified and better-prepped than the ones mentioned here. And yet when I asked Xavier about challenges, he was very transparent and offered a long list. For me, this is the ultimate test of confidence. If you have to pretend nothing ever goes wrong, you’re probably not a pro.
 
All the challenges Xavier mentioned were so familiar to me. And they’ll be familiar to everyone who builds. Plan changes, plaster, roofing, and volunteers, always guaranteed to make you sweat. Notice how Xavier deals with challenges, (namely flexibility, determination, and a good old prayer every now and again:))
 
1. Roofing stress. “The roof was very complicated with difficult angles and large parts to handle. There was very little space for error”, says Xavier, who had to organise the placement of beams weighing up to 300kg onto the roof. Yes it was stressful. And yes it’s a good job he’s a woodworking expert.
 
2. Dome moving outwards. “Another critical moment was when we noticed that the dome was moving outwards due to it having too many openings. We took the difficult decision to add several buttresses sticking out in the middle of the rooms, reducing their surface, but later these buttresses became nice features of the rooms giving support to the stairs or shelving”, explains Xavier.
 
3. Plaster troubles. I always say plaster is one of the trickiest parts of a build. It looks deceptively easy. It isn’t. “Exterior plasters were (and will be) a struggle. The building is very exposed to strong northern winter winds and lime plasters got badly damaged in some places. We repaired and reinforced this year but there might be much future maintenance needed at those sensitive points”.
 
4. Finishing that never finishes. “This actually took most of those 11 months”, laments Xavier. “Hundreds of details to care for, starting with the rough plaster phase”.
 
Yup brace yourselves. The structure is the easy part. The finishing phase is misnamed and should be called the punishing phase instead. It will demand every ounce of determination from you.

​5. What, no shower? “Another problem was the shower”, says Xavier. “That little room had been designed to house a toilet only, but the owner asked for a shower on the way”. He he he. Oh the joys of doing commission work. He continues, “Walls were there, a big wooden post in the middle of the only possible spot for that shower. So we embedded burlap mesh in the lime, waterproofed as much as we could, applied tadelakt over and prayed to whichever god deals with plaster cracks. A year later the shower plasters are intact”.
 
I love that they prayed to the plaster crack gods. And I love that it worked:))
 
6. Volunteers. “I can also add that having to work with volunteers is sometimes a major challenge in this type of project. Some people will be capable, learn quickly and turn out to be productive, others will be a burden whose work you’ll need to check constantly, perhaps even redo and waste even more time. It is a lottery”.
 
Oh preaching to the choir with that one Xavier! But despite the mixed experiences, Koluba are still bravely taking on new volunteers.
 
Want to Volunteer with Koluba?
Koluba are accepting volunteers with some woodworking experience this year. It will be a different location, in the beautiful Kazdağlar mountains near Çanakkale. For more details contact Xavier/Koluba at the address below.

​Contact Koluba (and see a stack more stunning photos) at:
Instagram/Facebook @kolubakolektifi
Website: www.koluba.org
 
Other related links:
**Architect: Matthieu Pedergnana @dogalmimar
***Location: @sihirlitohumlar
 
What is slipstraw? https://strawclaywood.com/natural-building-techniques/straw-clay-or-slipstraw/
 
* And if you want to catch up on a glittery piece of Turkish history (albeit glammed up to the hilt), then grab some popcorn and indulge in the historical romp that is Magnificent Century, one of Turkey’s best-selling media exports.
https://www.youtube.com/watch?v=N2ZlLE4z__4

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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.

It’s always hard to explain to people about leaving the grid behind if they haven’t experienced it. It’s such a different life, with different rewards and different challenges. I find myself either making it all sound like a herculean endurance effort, or some butterfly-filled, free food utopia. Being off-grid is both and neither of these, and a whole lot more. It’s another paradigm.
 
I could never return to the old ways, to working in the system, to having a boss or contorting myself to fit someone else’s timetable, to the pollution and noise, to the EMFs, to wi-fi, to the awful processed food, to the chemicals, aircon, and concrete. It’s unthinkable. I haven’t enjoyed running hot water for ten years, nor a washing machine, nor a fridge (not that these things are necessarily inevitable if you go off-grid). But despite the seeming lack of comfort, I’m still saying I’d never go back. I miss my land when I’m away just one night!

The trouble is, if you’re in the urban world and imagining life without a washing machine or a fridge, chopping your own wood, and boiling water on a stove, it looks hard. But that’s because you’re in a world that’s completely unadapted to those things, with days rammed full of appointments and rushing and nonsensical bureaucratic duties to the point that spending half an hour hand-washing would be a disaster. My days simply aren’t like that. I get up when I want and sleep when I want. I’m in a world where hand-washing could even be a pleasant diversion. I’m also not having my body and mind continually attacked by noise and pollutants, nor have I been sitting at a desk eight hours a day. You only understand what those things are doing to you when you live in a mud or stone hut without power cables long enough for your body to clean and revive itself.
 
On the other hand, when people don’t understand why I can’t make that hundredth flipping Zoom call, or why I can’t say for sure I’ll be free at 4:15 pm on Friday, or why I don’t want a puppy right now, it’s hard to explain. These people are flicking everything on with switches. I’m literally building every damn thing I use, from my bed to my water systems to my fire each night. And I’m reliant on the weather to do these things. So if it’s rained all day and the sun happens to pop out at 4:15 pm on Friday, I need to go and find wood, not chat on the phone!
 
Probably the best way to get an idea of the transition from the system to off-grid is to read my book Dirt Witch, but for a more right-brained approach, here’s a tidy(ish) list of pros and cons. Most of the cons are also pros though, as you’ll see.

“This is such a compelling book, it will make you want to abandon everything you know and commune with the trees and the dirt.” –Luisa Lyons

The challenges of being off-grid:
 
1. Being off-grid is very physical. You aren’t sitting on your butt all day, you are out there building, gardening, cooking, digging, chopping wood, dragging things up hills, moving rocks, etc. So you’ll get very tired at certain points, especially in the beginning when you are setting up. You need to learn how to pace yourself and manage your energy. Getting a puppy isn’t the best idea at the outset.
 
2. You are at the mercy of the weather. Climatic forces are the thing you’ll worry about most – not money, not admin, not power, and definitely not critters. Fires, snow and rain can all get pretty dangerous pretty darn fast. Your world and what you can do is entirely controlled by meteorological forces. You will understand what no one down there in the modern world seems to be able to wrap their deluded heads around. Nature is Queen, and we are her subjects. Forget your plans, they count for nothing. You will work with and around the weather.

3. Lack of structure. Some people find the freedom and open days a burden, some think it’s the best thing that ever happened. This does a bit depend on personality. Generally creative types do well when they are free. I have an inexpensive course on structuring your day outside the 9-5 for those finding their days are being frittered, or who feel lost in all that freedom.
 
4. Possible isolation. Again this is personality. Just be aware you are not in the hustle and bustle anymore, so there’s more space, more quiet time to stop and think. If you are a people-needer then make sure you buy land in places with people around and knit yourself a community.
 
5. Inaccessibility: You can’t just nip to the corner shop and buy yourself some salt if you run out. When you shop, you need to be focussed about the supplies you need. And when you’re back on your land you have to learn to use what you have well. Inaccessibility means you'll want to be smart regarding accidents too because it’s hard for ambulances to reach you, and hospitals are far away. Remember your first aid, have a decent first aid kit to hand, learn how to use herbs, get on with your neighbours, and be careful when hanging off ladders.

​6. Income: I add this a little doubtfully because I notice Westerners worry way too much about two things in their off-grid planning: money and electricity. That’s because in that other world, money and power are crucial. You’re leaving that old world behind though, so what counts there doesn’t necessarily count half as much when you’re in the countryside off-grid. Yes you still need a bit of money to get by of course, and make your life more comfortable, but 300 USD a month per person will usually be enough once you’re set up (depending on where you live it could be a fair bit less). Even so, for those of us who are more happy-go-lucky in the money department (ahem), you do need to consider how you are going to earn those 300 bucks. (see this article for more ideas on that).

7. Iffy internet: I forgot about this one, I’m so used to it. In fact, I’ve enjoyed some better internet connections off-grid, than some people do on grid. But you do need to consider that you’re probably not going to be using Wi-fi. I’ve been on pay-as-you-go metered internet ever since the internet began, and I work online! I actually prefer it because a) I don’t like Wi-fi signals, b) It means I have to be focused with my internet usage, so I don’t get lost on Youtube videos or Netflix for hours at a time. I write and store all my articles offline, and only turn on the internet to upload. For those who want limitless internet, there are off-grid options too, the most cost-effective of which is usually satellite internet.
 
The advantages:
 
1. Being off-grid is physical. You will get in shape. Fast. In the longer term, your body is going to thank you. We were designed for working in nature, and our bodies adapt incredibly quickly. You will lose weight while gaining muscle, strength, stamina, and overall health.
 
2. Freedom. You never have to get up to the sound of an alarm again. You never have to commute again. You never have to take crap from a boss again. You can set your own schedule and make your own rules. You are sovereign of your own life. And yes it is just as good as it sounds. Not a day goes by when I don’t wake up relieved that I don’t have to yank myself out of bed to reach some godawful job that I don't believe in any way.
 
3. No power or water bills. There are so many aspects to this I love. Obviously the financial aspect is one of them, but just imagine never having to go through the torture of phoning the water company to cancel or change a contract. And just imagine also having the beatific feeling of not funding some ecocidal CEO’s yacht in the Bahamas at the same time.

4. Enhanced creativity and problem-solving ability. Once you’re off-grid in nature you’ll begin to access your inner creativity, and solve all manner of problems you were previously so sure you needed to hire someone for. You start to realise you don’t need to buy half the things you thought you did, and you find yourself tapping into a wellspring of natural inspiration. It’s all very empowering.
 
4. Nature and wildlife. This is the part of the adventure most moderns are clueless about, and that’s such a sad fact. This is what I do it for! Nature is our home. It is impossible to relay the joy of living amongst all these creatures and observing the ever-changing beauty of the plant life, the sunsets, and the cloudscapes. Poor little rich moderns with their radiation-spewing screens and their soulless shopping malls, always feeling something is missing and never knowing why. This planet is a wonderland, and the ‘wealthiest’ don’t even know.
 
6. Resilience in the face of societal collapse. Depending on how well you’ve set up your system, and (more importantly) how well you adapt to working with nature, you find that pandemics happen, societies break down, and economies collapse, but not much actually changes for you. If you didn’t have some kind of media harrying you, you’d probably not even know!

7. Clean food and water
I’ve been drinking pure mountain spring water fresh from the source for about fifteen years now. If you like chlorinated, fluoride-treated, Lord-knows-what-esle contaminated mains water, carry on drinking from your tap, but you won’t convince my taste buds or my body that it’s healthier. There’s no comparison. Spring water from the source tastes and feels life-giving. The same, if not more, goes for shop bought vegetables. I still have to stoop to buying some of them, but the difference in quality is astounding. The only way to be sure your food supply isn’t contaminated with pesticides and poisons is to grow it or rear it yourself somewhere clean.

​If you want to know more about going off-grid you might like to try my free off-grid prep course. There are five questions you need to ask yourself before you take the plunge.

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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.

Courtesy of Helen Atkinson in Baltimore
 
Now for something a little different. Something a little fun. Not that Helen’s cob oven is particularly ‘little’. Au contraire, this wonderful project is quite the cob oven piazza:) Ah, there’s so much you can do when you learn the art of cob and earth plaster. Your imagination is the only limit.
 
As soon as Helen joined The Mud Home Facebook group last year, she began sharing her oven progress. What I loved about her posts was how she clearly enjoyed experimenting. This is Helen’s third cob oven now, and each time they get better and better. There's a lot of very good information coming here, no matter how much you've researched cob ovens, so do read it all.

 Why Three Ovens?
 
“The first one had way too many deep cracks in it,” explained Helen, “So I tore it down a few days after the build and rebuilt. The second one included a four-inch layer of insulation and was great. We had some lovely pizza parties, but when I forgot to put the tarp on and it rained, there was some definite erosion. Now the third iteration has a whole new (flat) floor under it and roof.”
 
Do You Need A Roof?
A roof over a cob oven is pretty much always recommended, unless perhaps you are in the desert. Rain will indeed erode that cob dome. But I love how Helen kept improving her design like this. Cob ovens routinely fail, for many reasons. I know when people experiment and tinker and redesign, they have learned deeply what works and what doesn’t. Not being one to miss an opportunity like that, I asked Helen for all her tips. This oven is very well done.
 
Many thanks to Helen for this very detailed explanation. It will be useful for anyone wanting to give this a go.
 
How Helen Made Her Cob Oven

1. First she built the foundation out of stacked prefab stones from the hardware store. “The ones that are used to build round fire pits,” says Helen.
 
2. Next she filled the empty round base (which was almost hip height) with ‘urbanite’ from a roadworks nearby. "We fetched it in wheelbarrows," said Helen. "And then added sand to fill the tiny gaps. After that I put a border around the base made of large and small river rock collected from a park nearby.”

3. It’s advisable to add a decent insulation layer underneath the actual oven. This helps the oven heat up fast (otherwise all the heat is sucked down into the base). A good way to do this is with a layer of recycled glass bottles. Helen embedded the bottles in sand and then about 3-4 inches (10 cm) of cob.

4. The oven base is formed out of fire bricks. “I put a 3-4 inch layer of cob on top of the insulation layer, so that the outer edges would meet up with the oven sides and be like a chocolate covered peanut. Next I put some sand down in which to arrange the fire bricks, laid the fire bricks carefully in the centre in rows and a large flat stone to stick out the front so I have a lip to drag the ashes out into a bucket,” says Helen.

5. The dome of the oven is made from cob. Here’s how she made the cob dome:
i) Helen shaped a sand pile into a round mound on top of the firebrick base (16 inches high).
ii) She covered the sand pile with wet newspaper (makes it easier to remove the sand at the end).
iii) She covered the sand mound in 4 inches of cob. This is the layer that is built to take the heat. Her tip here was to press the cob down and around the sand dome in a spiral (rather than patting it against the sand dome itself, which moves the sand around in the middle.
iv) Once that was completely dry, she carefully dug out the sand, leaving the clean oven floor (firebricks) with a cob dome on it (Sigi Koko has a great YouTube video on how to do this step).

6. Next she added a 3-4 inch layer of insulating mud onto her cob dome, that included dry hamster bedding. The hamster bedding is supposed to incinerate and create pockets of air. “A friend gave me an old cast iron stove door, and I built a doorway out of fire brick with a chimney made from an old piece of ceramic pipe, and used a stiff mud plaster to cover it all and hold the chimney in place,” Helen said.

7. Now that the oven structure was built, Helen plastered the whole lot with an earthen plaster she made with deer poop added (for the record: you don’t have to plaster the base of the oven, it was an aesthetic touch).

8. Next she decorated her new oven in beautiful mosaics and sculptures. Once it had completely dried she coated it an a whopping 7 coats of linseed oil. “I think this is what really saved me,” she said. “Even though I had built the shelter to cover the oven there is enough sideways wind and rain to wash the sides away without the oil.” Take note folks!
 
So there you have it. How to make a very good cob oven that heats up fast and doesn’t collapse in the first rain of the year.
 
Of course I have to ask what will come next. Perhaps an entire cob oven complex with cob benches and picnic tables and… Just joking Helen:)

The Top 3 Reasons Cob Ovens ‘Fail’
As I said, cob ovens do misfire quite often. That’s not really the end of the world if you’d like to just have a go. Ultimately we all learn from our mistakes a lot faster than we do from online commentators like me:) But for the record, here are the most common pitfalls:
 
1. The oven isn’t adequately protected from the weather. You really need it well covered, preferably by a roof. And if you’re in a rainy climate, some linseed oil won’t go amiss either.
 
2. Not enough air flow, so the fire struggles to get going. For the best suction, you want an entry point for air (small flue or tube, or open oven door), and an exit point for smoke (chimney or flue).
 
3. No insulation. This means it takes an age for your cob oven to heat up. If you’re baking pizzas all day this may not be such a drama. But if you want to get cooking fast, then insulate.

Related links:
Cob vs earth plaster, what's the difference?
http://www.themudhome.com/mudbuilding/earthen-plaster-and-cob-whats-the-difference

Introduction to Earth Plaster
 
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Lots of peeps are asking questions about building into the side of a hill, or semi-underground. I’m in a good position to answer this, because all my stone huts have been built into the rock face. In fact the barn uses the rock of the land as one of the walls. This is quite common in both Spain and Portugal, but brings with it some issues, the main one being damp.

Why build into the landscape at all? Despite the drawbacks people have been building underground for eons (there are 10 000 year old underground cities in Turkey). Why? Well there are quite a few perks to being a little lower down.

Advantages

• Shelter: You are much less prone to wind damage which is important in places with hurricanes and the like.
  
• Aesthetic: You blend into the landscape better and your house becomes a part of the land.
  
• Invisibility: You are less conspicuous, so for all those on the run it’s an attractive option.
  
• On a small plot, it can be a good use of land space too.
  

Disadvantages
The most obvious drawback is that underground houses are notoriously prone to damp, or worse flooding.

How to build underground
The key to a semi-submerged house is two-fold. You need a vapour barrier and decent drainage. Whether you are considering an earthbag bunker or a stone root cellar, the same applies.

1.Vapour barrier
I’m usually quite ambivalent about vapour barriers in natural homes, but this is the clear exception. You definitely want a vapour barrier (plastic tarp) on the exterior of your outside walls if you are underground. The barrier should separate your structure from the earth/rock outside. Some people even add a double barrier.

2. Drainage
Dig a decent trench all the way around your structure, line it with geotextile membrane and fill it with rubble (rubble trench). You could also add a french drain here, but do it properly (see this article). The main point about drainage that seems to get forgotten is gravity. You need a decent downward slope, and no amount of perforated plastic tube is going to help you if said tube is laid flat, or nearly flat. I often think a decent rubble trench lined with geotextile membrane sloping well downwards, works better anyway.

3. Guttering
This is super important. Make sure the water running off your roof, isn’t sinking into the ground around your building. Add guttering all the way round your roof eaves and channel that water away from the house and the ground surrounding it.

Extra note: There’s no getting away from it really. Submerged buildings often feel a bit damp. A good solution to damp is a wood burner. It will dry a building out very fast. But of course that’s only a valid option in a cooler climate. If you’re in the warm then think long and hard about ventilation and possibly a dehumidifier.

Which types of sustainable building suit going underground?
Now, there will no doubt be those who disagree, but having seen a couple of examples of strawbale rot in the damp, personally I wouldn’t be itching to stick strawbale underground. Nor would I prefer to use wood. The safest options are stone and earthbag because they can handle the wet. Hempcrete might also be OK but I haven’t seen any examples of that yet.

Related links:
Earthbag root cellar: https://www.wildernesscollege.com/earthbags.html
Underground earthbag room: https://youtu.be/8dM2It_T3nE
Rubble trench: https://cordwoodconstruction.org/rubble-trench-the-basics
Do you want a french drain or not? https://www.estormwater.com/drainage/french-drains-and-their-downfall

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​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
 
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​Here’s an innovative earthbag project to whet the more arty side of your appetite. Rhonda in our Mud Home Facebook group is making something rather stunning happen over in Mexico. This is an exceptionally well-designed build, with so many original architectural features, I wanted to showcase it. Rhonda was also incredibly informative in her documenting, which is very helpful for others, so a public shout out to her for that.

The Mexican Dream
 
But let's rewind a bit. How did this earthbag marvel begin? As always, it starts with a dream. Five years ago, after many visits to the country, Rhonda moved to Mexico. “I fell in love with the more simple way of living. Mexico taught me that all of the stuff I had accumulated in my past life in Canada and the United States was completely unnecessary, all the kitchen gadgets, 25 pairs of shoes, the matching set of pots and pans, everything that we think we can't live without or that we need to be happy.”
 
Oh and ain’t that the truth, eh? So our muddy artist ditched the Western fixation on ‘more more more’ and moved to Nayarit on Mexico’s west coast. “It’s the best decision I ever made,” she says. “There are always language barriers and issues that come up, but I happily accept them as challenges and experiences.”
 
We’ve been watching somewhat agog in our little Facebook group as this earthbag dome world has mushroomed out of the dust. Pretty much all you see below was built in the month of November. One of the greatest boons of the earthbag building technique is it boasts both strength and flexibility. You can do things with it that you can’t do easily with many other techniques. One of those architectural delights is the dome.
 
A Word on Domes
 
Now, before we go any further, and before a thousand more people rush out and decide to build a dome because hey they’re sexy, a word of caution. Domes are not for every climate. They pose many waterproofing issues for one thing, I'll be covering them in more detail next month, but in the meantime, don't say I didn't warn you.

Why Earthbag?
 
“For many years I investigated different methods of more natural ways of building,” says Rhonda. “There seem to be more and more popping up these days, different ideas all very interesting in their own way. It wasn't until I read your book Mud Ball and found your website that I became really intrigued and started soaking up all the information I possibly could.”
 
Rhonda sculpts dolls for a living, so it’s no surprise she would want to work with earthbag, which like cob often attracts artists because both allow the builder to literally sculpt a house. You are no longer restricted to post and beam structures, or inflexible building materials. The whole shelter becomes something to mould.
 
“I love that it's possible to experiment and include lots of different techniques artistically like sculpting and painting and stonework, just to name a few. Really your imagination is the only limit,” Rhonda says. And let’s face it, this might be her first build, but her imagination is certainly enjoying some legroom, even so.

So how did she and her team build it?

The Foundations
 
“We did two levels of gravel-filled bags below grade, and another two levels of gravel-filled bags above grade. Black plastic was added over the bags after the below grade levels were finished,” explains Rhonda. She’s really chosen the correct foundation and stem wall approach. I’ve said it many times, it’s hard to beat the rubble trench foundation for natural builds. It simply works. It’s cheaper than Portland cement, a million times better for drainage, fairly fool-proof and a lot more environmentally kind. I can’t see one good reason not to use it.
 
More on gravel foundations here.

The Earthbag Domes
 
These domes are made from earthbag PP tubing filled with stabilised earth. “I went with continuous bags and 50cm wide,” explains Rhonda. "After the gravel bag layers, we continued filling all of the next levels with dirt and lime. We added some plumbing and are going to be separating grey water out for recycling,”
 
The domes will comprise skylights embedded into the top. In this case the upper ring of the dome (where the skylight will sit) has been reinforced with a small concrete ring (bond beam). Bond beams at the point where a dome tapers in are sometimes used (or required by codes) to prevent the dome from splaying out under the pressure of the domed roof. These can also be made from wood, which I prefer not only for eco reasons, but because wood typically has more give than reinforced concrete. In this case though, the ring is so tiny and tight, Rhonda is right in my opinion to choose cement. You'd be hard-pressed to make a structurally sound wooden circle that small. "The other reason I didn't use a wooden bond beam is because we have a huge termite problem in Mexico. They eat up everything in a matter of a couple weeks and the only way to keep them out is to spray with some very hazardous concoction," explained Rhonda. And it's true, sometimes Portland is the lesser of two evils.

​The Keyhole Doorways
 
It’s not just the cluster of domes that is interesting in this build. For me it's the other features that are truly inspiring. I don’t think I’ve ever seen anyone make anything like Rhonda’s stunning keyhole doorways.

How did they make them?
 
The doorways are so clever. They were made using moulds that were engineered from tyres resting on wooden frames. The tyres were old disused ones, which made them a much cheaper recycled option than making wooden forms.
 
“I was able to find free tires for window and door forms and we wired two tires together for all of the window openings to make them wider because we're using wider bags. I'm using the tractor tires for the door into the indoor garden and one also going into the bedroom,” explains Rhonda.

This keyhole doorway is particularly exciting because it joins two intersecting earthbag domes.

What’s next?
 
“This first one, La Casa Montañita, will be my home and a very special build for me,” says Rhonda. But it won’t end here. It never does:) “I am planning to build on the same piece of property a Superadobe pool and a structure for art retreat and class students to stay in. I will offer and host classes for many types of art, sculpting, painting, doll making, stone mosaics and who knows maybe even Superadobe. I'm addicted to this method of building and it's countless possibilities. I'm sure there are many new projects in my future.”
 
Things to take away from this inspiring build:
 
1. Using wider bags: As Rhonda says, “I love the wider bags for the walls but it does make the work a lot heavier. We are also using an extremely heavy tamper and double rows of 35 kilo barbed wire so the bags are super solid.” When you use wider sacks in earthbag, it means you have to dig and fill a lot more dirt. But...wide tubes are going to be less of a strain than wide bags, because tubes don’t get ‘lifted’ onto the wall after they are filled. This is worth bearing in mind.
 
2. Stabilised earth: Take note, if you don’t have enough clay on your land for any reason, you can also stabilise your earth using lime in the mixture.
 
3. Planning and design: There are usually two camps: one lot spend their life overthinking everything and doing nothing (groan); the other bunch (ahem, me) leap straight in and muddle through, the downside being more potential cock-ups and extra expense (but  hey, at least something manifests). Then there is this rather admirable subset of folk, of which Rhonda is one, who plan things superbly well, and actually execute their plans as well. I have nothing but respect for such people. For the rest of us, it pays to know which side of the overthinking/reckless-and-rash boundary you sit, so that you can push yourself in the other direction.

See more on Rhonda’s dolls here: https://creamsodabjd.com
Keep up with her sculpted eco builds here: https://www.smudgez.com
 
Related articles you may find useful
My Free Earthbag Building Guide: http://www.themudhome.com/earthbagbuilding.html
More on the polypropylene sacks: http://www.themudhome.com/the-sacks.html
Gravel/rubble trench foundations: http://www.themudhome.com/gravel-foundations.html

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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.

Yay! The cob hen coop is finished. There's even a bit of grass growing on that roof. So here it is: How to make a smallish (1.5m diameter) cob chicken coop, including a living roof and limecrete floor (yes my hens live in style).

Note to all the folk who love to read this stuff, but never do it: This is the one time you should quit the procrastinating, and just give it a go. A cob coop/kennel is perfectly doable alone, it costs basically nothing, and you don't need a permit for it. That's it. I've just set a match to all your excuses:) No garden? Make a small cat house in the park or something! An animal shelter is a super way to practice using cob. It’s basically a miniature version of a house, so you get to try out all the techniques on a manageable scale before committing to a more ambitious structure. Yup, it really is time to get your hands dirty!

First, dig a small trench/circle for the foundation. This is a hen house, not a castle, so it really only needs to be 10-20cm deep. Fill it with nice fat rocks. Then fill in the gaps with smaller rocks.

Adding gravel over the top isn’t strictly necessary, but it fills in all the tiny gaps and creates a nice flat surface to build on. This is especially useful if you’re adding a limecrete/earth floor.

Mix up some cob. I used roughly one part clay, one part soil, one part straw, some horse manure ,and two parts sand. But each person’s mix is different, so test it. If you want to be very professional and master the art of clay plaster and cob, take a look at my Perfect Earth Plaster Course.

Now add another ring of rocks for a stem wall (to raise the cob off the ground so it is protected from rainwater runoff). This is an important feature with all mud buildings, so don’t skip this part unless you especially like watching cob disintegrate in water.
 
I wanted to test out both a limecrete and earthen floor in my climate, so I made the chicken coop floor half and half. I also wanted to test out whether a vapour barrier was a good idea or not. Hence I laid some plastic between the gravel and the mixture in one half of the coop, but slapped the mixture straight down onto the gravel on the other half. Now that I’ve seen how it functions, I think these natural floors work much better without the vapour barrier (others disagree). What I’m seeing is, the half of the floor where I stuck the vapour barrier doesn’t dry out properly because the damp can’t evaporate.

Take your cob mixture and slap it on top of your stem wall to create your first mud layer. Wait for this to dry before adding the next layer on top. In my climate (damp) I found I could lay about 30cm (height) of cob mixture at one time, after which it began to buckle.

Add your door frames wherever you want them. These need to be properly anchored into the cob mixture. You can see from the photo how I created small lintels above and below the door, which extend into the cob. These were nailed into the cob mixture below. I also added nails (see the red lines) into the side of the door frames so the cob has something to stick to.

Keep building up and around the frames until they’re completely embedded into the structure.

Once you reach the top, add some ‘wall plates’ for your roof to sit on. Again these should be anchored into the cob. I nailed mine in.

Before the roof goes on (if it’s a smallish coop), sculpt the inside. It’s a lot easier this way.

Add your roof joists. I used bits of old wood I had laying around. Make sure they’re level, and that the roof is sloping gently from front to back.

Use some sort of roofing board to cover the joists. Cut it to the shape you want and screw it in place. Then add a water proof membrane of some kind. You can add hens as well at this stage, if you want.

Attach a rim to the edge of the roofing board to create a kind of tray for the dirt to sit in. In this case I used skirting board, but hey, use your imagination and whatever you have to hand.

Remember to add mesh at the back so that water can drain out.

For a living roof you need a root barrier. Bitumen based membranes, Onduline, or roofing felt won’t be enough because roots will soon eat through them. Sadly plastic is the only way here (as far as I know).

Normally on a human house you’d want a drainage layer here (see how to make a living roof here).
​
Because this is a tiny hen coop, I didn’t bother with that and stuck the dirt straight in.

In about six months the roof should be green. But in the meantime, the hens are happy and snug.

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Step by step how my roof was made
Roofing is the trickiest and most important part of a house build. As I’m sure you know, the roof of my old barn is on! It’s covered in beautiful traditional Spanish curved tiles too (collected from anyone I could lay my grubby, pertinacious hands on). But I’m not going to lie; I’m not a fan of tiles. Living roofs will always be my favourite. There are so many advantages to them, and they are a heck of a lot easier to construct.
 
Even so, in many places in the world, the tiled roof is the norm. So here’s exactly how we (ahem, Brian) made mine.

​1. Raising the roof and squaring the trapezium
I wanted to slightly increase the height and pitch of my roof without impacting the character of my old barn. So first the walls were built up and levelled using clay bricks mortared with limecrete. As every single wall is wonky (the barn is basically a trapezium), this was trickier than it appeared. The roof (which is rectangular) needed to squat on the barn at a slight angle. This is of course a neurotic’s nightmare. So if you like everything minutely straight, all I can say is don’t buy an old building. Me? I like the incongruity, and it’s perfectly in keeping with the nobbled, nothing-is-straight personality of my old Asturian barn.

2. Adding the wall plates (15cm x 15cm)
Next, two 15cm x 15cm wall plates (horizontal wooden beams that rest on the walls) were mortared onto the bricks with NHL (hydraulic) lime. Why hydraulic? I wouldn’t recommend lime putty here, even with a pozzolan, a) because it takes too long to cure fully and you need that roof structurally sound fast, b) NHL lime is more cementitious than soft lime putty, and in heavy structural jobs like holding a roof on, that’s what you need.

Important note: You can't just mortar the wall plates on and hope for the best. They need to be tied down to the wall. I mention this at the bottom of the post, but it's since become clear people don't read that far:)) I'm still tying the thing down, but once it's done, I'll share that bit too.

3. The ridge beam (15cm x 30cm)
Once the walls had been levelled and the wall plates were attached, things turned rather exciting on Mud Pico. We needed to lift the massive central ridge beam up and across the middle of the barn. It was a momentous day sloshing with adrenalin, and frankly by noon I thought someone would die (or at the very least suffer a hernia).
 
We couldn’t use a full 8-metre beam because we had no cranes nor machine lifting tools, just human muscle. For those in the rich West, who to my Turkish way of thinking seem to be extremely dependent on machines to do everything, just note: where there’s a will, there’s a way.

So in fact there are two 4-metre-long 15 x 30s joined together to create the 8-metre ridge beam. The beam is supported in the middle by a vertical central pillar (two fat pieces of ancient chestnut), which all rests on a horizontal 200-year-old massive chestnut beam that runs through the middle of the barn.
 
Important note: The two ridge beams aren’t just screwed together using brackets! Notice they are bolted top to bottom onto that horizontal angled wooden brace, which then rests on the vertical central chestnut pillars.

4. The rafters (7cm X 15 cm)
My roof comprises 32 rafters (16 on each side), and all have been bird-mouthed to fit onto the wall plate and the ridge beam. Each of those bird-mouths was hand-sawed by Brian. For those doing the math, yes that’s 64 bird mouths in 7 x 15 rafters. And yes, that is indeed hard work:) It seemed like the poor guy was sawing for about a week. Brian, however, was stoic in the face of this brutality, merely murmuring between the clouds of sawdust things like, “who needs a gym?”

5. The spacing
My rafters are fairly heavy-duty (7cm x 15cm), so for my tiled roof, a 50cm span between each rafter was ample.

6. Roofing Boards
Now, if you have plenty of money and time, you would lay some lovely wooden roofing boards at this point, then add your insulation on top of that, then roofing felt, and finally tiles.
 
Me? I was out of money and very very pushed for time. So we screwed a kind of chipboard (sawdust heated with resin and turned into planks) straight down onto the rafters. I will add insulation and some pretty cladding on the inside later when I’ve saved a bit of money.

​7. Waterproofing
This for me was the most annoying part of this roof. If you are building a modern house with normal roof tiles, then all you need to do is use a lovely permeable roofing membrane, and you’re away. I’m not building a modern house. Basically I live in a museum, so I am bound by law to use tejas curvas, which sounds like something the inquisition threatened witches with, and in retrospect probably is.

Tejas curvas (curvy tiles) are of course much more beautiful than their less exacting modern counterparts. In truth, I would probably have used them anyway out of respect for tradition. Personally I think tacky soulless ugliness is as visually polluting as bitumen membranes. But...lovely as these tiles look, I cannot deny they involve a colossal waste of resources.
 
Tejas curvas cannot be nailed into place. In bygone years, when wood was aplenty, the locals would use chestnut beams separated at a fairly staggering 15cm, and rest the tiles in the gaps. Today of course, this is an unthinkable waste of trees. Also, in those days, every time a tile cracked you had to replace it fast as your roof would start leaking. So for these tiles some kind of waterproof membrane is necessary.
 
Today, especially for tejas curvas, a type of bitumen membrane has been produced, complete with ripples that you rest the tiles in. You might argue that bitumen in and of itself isn’t so bad compared to plastic (I mean at least it breaks down – plants can grow through bitumen in a few years), but I daresay other crap is impregnated in the bitumen to mould it into a harder rippled shape.
 
Is there another way?
If you have time and money, you could I suppose lay a nice permeable roofing membrane down (though hey, I’m pretty sure these involve micro-plastics somewhere too), and then create the ridges for the tiles out of wood (which, unless you are recycling, has of course been cut from somewhere). Whether you deem this method more or less ecological is a matter of opinion.

8. The tiles (tejas curvas)
I’m sorry to say the tile drama doesn’t end with the bitumen boards though. Once those are down, you’ve now got the unenviable job of fixing those wretched tejas so that they don’t blow away in the fairly gusty Atlantic winds that charge around up here. Traditionally, folk covered their roofs in rocks. I must say, I quite like the rocks myself.

​On my other two small cabañas, I used limecrete to stick the tiles together. This mostly worked, except on one edge, where ultimately I had to add the rocks again because they were ripped off in a gale. The trouble was, limecreting the tiles together was utterly exhausting, material-heavy work, and I hated every minute of it. This was actually the original reason I decided to get someone else to do my barn roof. Limecreting those tiles really broke me (carrying heavy buckets of crete on the roof, plus a water bucket, and trying to fix the tiles without dislodging the ones you’ve just mortared all on a pitch far too high...nah. Not doing it again.
 
So when Brian took up my roofing gauntlet, I simply did not feel I could ask him to do what I wasn’t prepared to do myself. He wanted to use tile glue, and frankly I just let him. It isn’t eco. It isn’t nice to use either, in my opinion. But on the plus side you don’t need much of it.
 
In hindsight, what do I recommend for tiles?
If you use all brand-new tejas curvas, then there is a better option. You can fix them with special clips, and use minimal limecrete or glue. I especially wanted to retain the old look of the barn though, so my second hand tiles were far too warped to use clips with. I think a lot about what I would have chosen to do had it been me wrestling with those tiles. Honestly I’m not sure. But maybe, just maybe, I’d simply have slung them down and ballasted them with rocks, like the old days. That would of course mean I’d be up there again in a couple of years repairing and replacing, but the tiles would at least be easier to lay in the first place. Hmph. Tejas curvas, it’s a tough one. If anyone has come up with anything easier and more sustainable, let me know.

Still to do:
I’m very grateful to Brian for the incredible effort he put in to making me a solid and beautiful roof. I also learned a stack of things from him in the process. Brian and Julia’s shift is over now though, so the rest is up to me:) One crucial structural job that people all-too-often forget in the heat of the roofing adventure, is tying the thing down. I know more than one person who has seen their roof fly, or lift alarmingly. It might seem impossible with the weight of it, but if a heavy gust can get under an eave, it can start to lever it off the wall. In my earthbag house in Turkey, we tied the roof down with ropes cinched through the earthbags. Stone houses are different though.
 
Roof and wall ties
I have a number of techniques I’m using to tie my roof down, and will write a separate post on it next month once it's done and I have photos to illustrate it.

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The top ten natural insulation materials, and how to use them.

If you live in a cooler climate (or indeed a hot one and need to keep the burning summer sun out), no matter which kind of house you build, insulation will be on your mind. Without a shadow of a doubt the most important areas to insulate are the roof (60% of your heat disappears out here), and the floor (at least another 10% of your home’s warmth is sucked into the ground).

But there are quite a few natural materials to choose from, and all are suited to different jobs. Some are naturally easier to use for roofing, while others work better under the floor. Here’s a quick guide showing the pros and cons, approximate R Value, and usage of each type:

R Value? Oh no, what’s that?
Insulation levels are measured in R values. Here’s a neat little infographic for US climate zones showing the kind of R values you would need for your roof, floor and walls for a conventional house in various climates. All building materials have an R value per inch. Bear in mind though, some insulating materials work in different ways (for example, if you compress certain materials like wool, then you reduce their capacity to insulate).

Cotton bats (sometimes mixed with wool) (R 3.7 per inch)
Pros: Easy to move about, easy to source, snug, clean and warm. Pleasant to touch. Not usually expensive.
Cons: Mouse heaven. These perform better in the damp than wood insulation, but worse than say cork. Can be squashed (and lose some of its insulation power)
How to use it:
For roofing pin it somewhere between your roofing boards and your waterproofing.
For flooring create a wooden framework under your floorboards and insert it in the gaps between the floor joists. Consider a vapour barrier beneath the bats and the substrate (if going straight on the ground).

2. Wood insulation (R2.5)
Pros: Can be bought in easy-to-use panels or boards.
Cons: Can be difficult to source if you are in the sticks. Not the cheapest material either. And of course mice love it, because it's fibrous and soft (not solid wood). You can buy denser panels, but I'm guessing mice would still get into them. Wood insulation is also quite sensitive to damp. And of course a bit hopeless in a fire.
How to use it: If you want to keep the mice out of it, I recommend laying a metal mesh underneath it and over it. Lay the mesh first, slap the wood boards down, then wrap the mesh over the top and around. For roofing, wood insulation works best somewhere between your roof boards and your waterproofing. For flooring I’d only use it if I was sure there wasn’t damp anywhere in the equation.

3. Cork boards (R 3.5)
Pros: Fireproof. Mice aren’t especially into it. Easy to install. If you get the sanded version it looks so good you may not wish to cover it.
Cons: Ants are into it, sorry to say. More expensive than some other options, and not available everywhere.
How to use it: Cork is super easy to use as it comes in sturdy-ish boards. For roofing it’s perfect. Tack it somewhere between your roofing boards and your waterproofing. For flooring you need a flat surface to lay it on. You could create a wooden framework under your floorboards and insert it in the gaps between the floor joists.

4. Perlite (R 2.7)
Pros: This is a volcanic glass super for flooring. It copes well with damp, is sturdy, not prone to rotting, fireproof, and mouse-proof.
Cons: Can be hard to source.
How to use it: I don’t see how you can use this for roofing (perhaps by pinning up sacks of it, but it’s not particularly well-suited). Perlite really shines for flooring, though. You can lay a fat layer of these small rocks on top of some geotextile membrane, and stick your floor of choice onto it. If using under an earthen or limecrete floor, you’ll want another layer of geotextile membrane on the top of it to prevent your liquid flooring from sinking into the rocks before it dries.
 
5. Foamglas (R 3.4)
Pros: Foamglas is a bit like perlite, though inorganic, which is to say not natural. However it is probably more sustainable than its natural volcanic sister. It boasts the same advantages too. It copes well with damp, is sturdy, not prone to rotting, fireproof, and mouse-proof. It’s more readily available than perlite too, and although it’s inorganic it is breathable, which is important.
Cons: Not natural, but probably more sustainable in the long term than perlite.  A bit pricey, but getting cheaper as it becomes more popular.
How to use it: You can buy foamglas in panels or as small coal-sized rocks. The panels are best for roofs, the rocks for floors. You can lay a fat layer of these small grey rocks on top of some geotextile membrane, and stick your floor of choice onto it. If using under an earthen or limecrete floor, you want another layer of geotextile membrane on the top of it to prevent your liquid flooring from sinking into the rocks before it dries.
 
6. Pumice (R value not found)
Pros: Pumice has the same advantages as perlite and foamed glass. It copes well with damp, is sturdy, not prone to rotting, fireproof, and mouse-proof. It’s also very light, which makes transportation and wheelbarrowing a lot easier, which counts for a lot when you’re out in the sticks.
Cons: Can be hard to source.
How to use it: Best for floors. As with foamglas, you can lay a fat layer of these small rocks on top of some geotextile membrane, and stick your floor of choice onto it. If using under an earthen or limecrete floor, you’ll want another layer of geotextile membrane on the top of it to prevent your liquid flooring from sinking into the rocks before it dries.

7. Sheep’s Wool (R 3.5-3.8)
Pros: Snug, doesn’t need much processing, and if you have sheep in your area then it’s an obvious, sustainable, and natural choice.
Cons: Wool has a bad reputation for attracting moths. Some say if you leave the tannin in the wool, this deters them, others disagree. And the tannin smells, so… I must admit I suspect the moth thing depends on other factors, because I have sacks and sacks of wool in my old barn (it’s been there at least twenty years) and no moths. The wool hasn’t been washed though, so the tannin theory may be correct.
How to use it: For roofing I’ve heard of folk filling bags or hessian sacks with it, and pinning it to the roof, or creating a wooden frame and stuffing it full of the wool. For flooring it’s easier. You can simply stuff it under floorboards, but make sure you seal it in well. Leave no holes for mice or moths.

8. Straw (R1.45)
Pros: Cheap as chips, easy to source (in many places).
Cons: Mouse heaven. Not as insulating as many of the other options, which means you might need half a metre of it to keep warm.
How to use it: I’m not sure about using straw in the roof. I suppose you could create a framework between your roof boards and your waterproofing, and ram it in there. But it would be difficult to seal it from mice, and you’d need a heck of a lot to really insulate well. For flooring you could potentially lay a vapour barrier, then stuff it under your floor joists, then add your floorboards. Laying a wire mesh all around would help deter mice. But yes, mice love straw. In my opinion, straw works best for walls. Slip-straw (a method of mixing a lot of straw into a clay slip, and then wedging it into a framework) is a good way of using straw for wall insulation.

9. Papercrete with lime (R 2.6-3.2)
Papercrete is the method of mixing paper with lime to create a nicely insulating crete with a surprisingly high R value.
Pros: Very inexpensive, easy to make, pest-proof.
Cons: Messy to apply. Not for roofing.
How to use it: For flooring you could create a massive slab of it, and then add the floor of your choice over it. Works best as an insulating render though.
 
10. Hemp (R 3.5)
This is the trendy new kid on the natural building block. You can buy hemp loose, in flexible rolls like wool, or in boards. The boards are great for ceilings.

Hempcrete (or hemplime) (R 2.4)
Like papercrete, this is lime and hemp mixed. In some places you buy it already formed into blocks, which makes it easier to use.
Pros: Inexpensive, fireproof, mouse-proof and generally pest-proof.
Cons: Hemp can be difficult to source depending on where you live. Messy to use and apply. There have been issues in cool, damp climates of hempcretes not curing adequately. This is usually due to using a very soft lime putty. If you are in a cooler, wetter climate, consider a more hydraulic lime for this.
How to use it: Hemplime is better suited to floors and walls. For flooring, you can lay a fat slab of it on some geotextile membrane, and then add tiles, wood, or earth over the top.

Extra: Cardboard (R 3-4)
The humble cardboard is a very useful material with a high R value. If you’re strapped for cash and need something to keep the cold out fast, you could do worse than use corrugated cardboard. I actually stuck this under my floor beneath some cotton bats.
Pros: Cheap, nay free if you head to the recycling bin. Easy to source, and easy to use.
Cons: No good in the damp, and rots very fast. You need a lot of layers to get a decent insulation value for a very cold climate. Not very durable.
How to use it: As it comes in boards, it’s really easy to use and can be tacked into place on a roof, for example. I’d see it as a short-term option, and I’d stick a vapour barrier under it if it’s going near a floor.
 
Earth, concrete, and insulation
People babble on about earth houses being bad in cold climates, but heck, earth is way way way warmer than Portland cement. I’ve experienced it firsthand, and the numbers agree. Concrete has an appalling R value (R 0.08). compared to earth (somewhere between R 0.15 and 0.2). This makes earth at least twice as warm as concrete. If you’ve got straw in that earth mix (which you probably will have) it’s automatically more insulating too. So, if you’re wavering about earthen houses, but have lived in concrete the rest of your life, you’re going to be pleasantly surprised. That said, for those in the seriously cold zones (below freezing for months at a time), earth houses will need insulating. More on earth and cold climates here.

​Insulation Summary
1. The roof is your priority.
2. The floor is your second priority.
3. Find any little draught hole and close it.
4. If you have a house with thermal mass (earth or stone) it is generally recommended to add insulation to the outside of the house walls.
5. But if you can’t do that for any reason, it’s still worth insulating the inside.
 
Best for roofs
Cork panels
Cotton/wool bats
Wood insulation boards
Foamglas panels
Hemp boards
 
Best for floors
Foamglas
Perlite
Pumice
Hemplime
 
Best for walls
Papercrete (lime-based)
Hemplime
Insulating earthen plaster (read more about that here)

How to keep mice out
Mice are insulation-loving, upholstery-chewing, corner-pooping little scoundrels. The only real way to deter them from your insulation is to seal it. Thoroughly. They will chew through almost anything other than solid wood beams, stone, and wire mesh. Find every hole, crevice and gap and fill it with lime mortar or earth plaster (though they may even chew through the latter too, eventually).
 
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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.