Building a cob house requires gathering the necessary materials, including clay soil, sand, straw, and water. Clay soil is the primary ingredient in cob construction, while sand is another crucial component. Straw is used to add tensile strength and prevent cracking. Water is essential for activating the clay and allowing it to bind with other materials.
Cob is made from the soil beneath your feet, excavating the subsoil beneath the thin layer of topsoil. The topsoil is the thin layer of dark dirt that contains mostly organic matter, while the subsoil beneath has very little organic material. Cob houses are not mainly composed of synthetic materials but are built out of natural resources like sand, clay, straw, and water.
To build a cob house, follow these steps: gather materials close to your building site, such as sand, clay subsoil, straw, water, tarp, and buckets. Mixing these ingredients with aggregate (course sand) and fiber (chopped straw or chopped horse hair) produces a lime plaster that will make a durable and natural wall. A 75:25 sand:clay ratio is recommended, and all of this needs to be filtered to less than 0.5cm.
Cob house construction is an ancient British method that uses lumps of earth, sand, straw, and water to construct various structures, such as homes, barns, and coops. For cob and other types of earthen building, pure clay is not needed; instead, a clay soil with a high enough clay content is needed to act as an adhesive for the materials.
In summary, building a cob house requires gathering the necessary materials, such as clay soil, sand, straw, and water, to create durable and natural walls.
📹 Building with Cob – A Natural & Affordable Way to Build a House
Bryce from Dreamweavers Collective explains the benefits and challenges of building with cob! Cob is a natural building material …
📹 How To Build A COB HOUSE | Introduction & Building Design
In this tutorial series we will be learning step-by-step how to build a cob house from the foundation to the roof. Cob is a mixture of …
That’s true, cob houses are very strong. In my home country, Afghanistan, houses are mainly built from dirt. Even the flat roofs are made of clay and joist from tree trunks for support. It’s bullet proof. Even if you hit it with mortar rounds, you can’t completely demolish. In winter, when it snows, you go up the roof with your wooden snow shovel and clean the snow. We used to replace the top layer every time we noticed a leak in the ceiling. Top layer has more straw to make it more erosion resistant. So one layer could last a year or two depending on the amount of rain in a year.
I am from Bangladesh, there is an area in Bangladesh called Bogra. In the countryside, there are mud houses that go up to three stories at times and they last for decades upon decades through the typhoons, flood and earthquakes. I am not from Bogra but where I am from there are mud houses too. They stay very cool during the summer. Same with mud mosques even though we have people crowding into them. The mud mosques in Mali are centuries old. Some are now about a 1,000 to 1,300 years old.
Is cob suitable for building a 400~500 sf cabin in colder, often wetter climates such as in northern parts of Canada? I’ve been studying conventional construction and building science extensively, but now am seriously considering building using natural materials. How would you recommend learning cob construction to do myself?
Thank you for this valuable article. In the Netherlands, it’s known to people with physical joint issues, and asthma, breathing issues, that living in an environment of cob, often helps to recover to good health again. There are homes, which are now changed inside, covered with cob, so that the resident can enjoy better health. I’ve worked with cob in Spain, in a small remote village, where a family man created a cob house on his vineyard, and worked with volunteers, in 2014. He used a small machine, like a plough, to break open the clay around the building plot, and we mixed the clay with straw and other ingredients, some sort of sand and fine chaff-like material as well. The three of us, two down at the heap of mixed clay, throwing clay balls up, worked on the walls, shaping a variety of rooms. The roof wasn’t present, of course, that’s always last, when building with cob, at least when you start from scratch. It was wonderful and fun, mixing the material, and to work with it to build up the walls. When dry, it was hard and sharp like glass. The climate was excellent, combined with the building material right there to be used, in that place. I’ve also helped cover walls of strawbale homes with clay, in Britain’s communes living off-grid, and later, in the Netherlands, where gradually possibilities to build your own home just to your liking are developing. Empty stretches of land, or where glasshouses are removed due to old age, are chosen to be offered to self-builders who buy the plot, and are free to design and build their home.
Idk if it’s genetic or does every man enjoys: 1. Planing and building stuff. 2. Going off to the forest. (Picking mushrooms, berries, hunting and fishing). 3. Eating food that you just harvested. 4. Sparring. 5. Learning how the universe works so you can plan and predict stuff (physics). It’s just makes you feel something. Meanwhile 8 hours at a desk is torture.
when he said 3 parts sand, 1part clay, i knew this guy knows what he’s talking about i did myself some compressive tests with clay-sand blocks and the ideal ratio is like 1:3 also adding straw really rise the tensile strength a lot one adobe brick could carry like 60kg on the 3 points test the material is almost perfect if it wasnt for the low water resistance but there are ways to protect it from heavy rainfalls and rising water tho
Awesome article! Bryce seems like an interesting person and a knowledgeable one as well. I’m curious about how building inspectors and architects treat this material. By the way he described it and from what I know of regulations, it seems like it would be hard to actually put up a structure, especially approaching a city/town. That said, it looks like he was making cob on a street, not on a farm or the like. Anyone have any ideas or insight? Thanks!
There are Cobb buildings in the UK that have been around for many, many centuries, but the oldest known cob structure is over 10,000 years old. It is still standing because it has been looked after by generations of people. Like all structures, cob buildings need care and attention from time to time. Simple checking for erosion and repairing damage before it becomes a problem is key to the longevity of cob buildings. A fresh coat of lime wash to renew the weatherproofing and protection every so often will extend the life of the cob as well. Oddly enough I was part of the crew that worked on many of the Cobb buildings in this article. I took several Cobb building workshops with Patrick Hennebery and his cobworks crew!
Adobe (Cob) has the advantage of thermal mass. It absorbs, stores and emits heat. This stabilizes the temperature of a building keeping it cool in the summer and warm in the winter. Once it gets warm it stays warm and once it’s cool it stays cool. In the Southwest it is often paired with passive solar heating.
Nice job Bryce! Thanks for spreading the word! Next time you’re back in Bandon come see all the great cob structures we have built since you were here last. You’ll love the lighthouse fresco! Or come down and stay awhile and help fresco the new Surf Shack!!! Keep up the great works….hugs from Oregon! Tammy
How do you test your soil to see if there is enough clay ? Guessing you have to do the build quickly and get a roof on before a big rain comes in and destroys your build ? Thx very much ! I am 61 and recently retired. I’ve always wanted to build a cob house. We are currently in Nicaragua but traveling between Mexico and Argentina, in search of our favorite retirement city. My wife is not really sold on living in a cob house so it may be a project for me and hopefully she likes it when it’s done. Otherwise it may end up being my man cave. 😃
I’ve built a small room out of cob and earthbags by myself on my property which I’m happy with. If you are considering building with cob, keep in mind it is very labor intensive. You can imagine how much work went into that one batch he’s making by hand, now imagine how many times you’ll need to do that to make a house from it. Great way to build, but make sure you are up to getting dirty and doing a lot of work.
this is Rural India technique and ofcourse much older technique nd equivalent similar time or before Indus valley civilization technique……some more older… you can see lots of houses in rural India with this technique before bricks this technique was and is used Thanks to bring it again t0 the world
I love this and wish it could be found more readily around the USA. The house that I grew up in was in my stepfather’s family since the early 1900’s (like 1901 ish). It is literally falling apart. We’ve done some upgrades to it but the whole thing is slowly rotting away. It should have been demolished years ago and built new. 118 years old and on its last legs yet these cob structures have been standing in other parts of the world for hundreds if not thousands of years. I’m sure greed plays into a lot of this as I don’t see these cob structures being all that large. A sign of wealth is a massive house and it’s probably easier to use conventional building materials.
in Ukrainian villages you can still find lots of houses made of saman – sun-dryed bricks made of clay, straw and sand, especially in the South, where wood was not that accessible. I used to live in my grandma’s house with saman walls and stove heating, the perfect house – warm in winter and cool in summer.
I’ve wanted a cob home for a while now. I will someday build my own cob home.! They are so beautiful, natural, and sturdy. They seem soooo much better for the environment and are built stronger than any “new” house. I wish the government (or people in general) would catch on to the pros of these as houses. Maybe they will catch on 😁
When building a cob structure, and you’re ready to finish a wall,.. is there something you should coat the walls with like a plaster,, stucko, or a type of paint to act as a sealant,..? I was wondering because on the inside parts where theres a bench like a bench over a Rocket thermal mass stove tunnel, to keep the sand and dirt from getting on your clothes and blankets when you sit on them,.. Thanks
Hi. I’m Chandan. Chandra from India. Your concept is awesome. I am interested in making mud/bamboo House and do also have people to make but the problem is that they can’t make stylish, differently. I will be highly obliged if you provide your support regarding the matter. Waiting for your response please
Hey, Bryce! (Or others who know this). Is this possible to use when building homes in Norway? Keep in mind cold periods of time where the temperature goes beneath -30 celcius. Not every winter now a days actually, cause it´s gotten warmer here. But, definitely below 20 on the regular. Do you use any other structural materials as a sceletone within the cob ? Like logs or metall or other? How do you integrate the floor and walls on the first floor? And, I see they all have wooden roofs and walls if a second floor. How do you integrate that to the walls below so that they don´t collapse? Thank you! This looks very interesting and nice! 😀
Doesn’t 3rd generation mean that he learned from his father, who learned from his father? Maybe not father, maybe mother… But how does learning how to cob at a workshop make him a 3rd generation cobber? That implies that it runs deep in his family history and I didnt hear a word mentioned about anyone else in his family. I am a 5th generation baby. By that, Im here, my mother is here, my grandmother too, and then her mother, and her mother were all still alive when I was born. That’s generational. He threw me for a loop when he said hes a 3rd generation cobber but yet learned at a workshop… or maybe Im off? Could be!
Does anyone know about how long it would take a single person to build a 200 sq ft house with cob? Nothing fancy/artistic. Just the 4 basic walls. Every cob house building I’ve seen is with a group of people, and I know it’s more labor and time intense than other build methods. Just wondering if it’s practical for one person to build it.
The 1990 Manjil–Rudbar earthquake occurred on June 21 at 00:30:14 local time in northern Iran. The shock had a moment magnitude of 7.4 and a Mercalli Intensity of X (Extreme). Widespread damage occurred to the northwest of the capital city of Tehran, including the cities of Rudbar and Manjil. The National Geophysical Data Center estimated that $8 billion in damage occurred in the affected area. Other earthquake catalogs presented estimates of the loss of life in the range of 35,000–50,000, with a further 60,000–105,000 that were injured. This was from wikipedia In that earthquake 500,000 people became homeless. 700 villages turned completely leveled up and other 300 villages damaged. That was end of cob houses.
The guy talk like it should be a replacement for casual building materials!! Well, that’s not true, and cob will never replace the bricks cement materials, obviously for so many reasons, especially with the current weather conditions! Still, you can do the cob work in the interior of your house if you really like it.
Although I enjoyed the article I really wish someone would do a more in depth tutorial of a complete cob structure build that’s well documented. There really isn’t much on YT beyond the This Cob House website and they really don’t want to show people everything because they’re more interested it seems in making money by getting people to attend their “workshops”. I’m working on buying 10 acres of rural property that I plan on building about 4 cob cottages on for couples to rent as getaways and a cob house for myself. I’ll be damned if I do all that work and not document the shit. Someone needs to put together and upload some really good articles of the entire process.
Hey. Very cool article. I was wondering if you had ever heard of anyone putting cob over straw bales? I live in great plains and native limestone house are very common, I’ve seen sod dugouts, and also a lot if strawbsoe houses. Usually the bake houses are covered in stucco but I like the idea of a more permanent solution, something I do once and don’t touch for like twenty or thirty years. I had wondered about concrete. But this article has me interested in cob. Any feedback would be appreciated.
Hello Exploring Alternatives, I would like to ask for your permission to re-use this article in a non-profit project called International Voluntary Service for Climate Justice. We are producing content with some earth-builders from the University of Santa Fe, Argentina. Our agenda is focused on promoting climate justice through things like bio-construction. Let me know if we can use parts for our purposes by republishing them online, with the source credited and mentioned. Thanks in advance! MA
This is what google first article says; Cob vs. Rammed Earth. … Rammed earth is stronger than cob and less prone to shrinkage as the mix is compacted and requires less water, shrinkage and subsequent cracks being caused by water evaporation. Cob and rammed earth can be used for floor and wall construction.
Government should Allow cob cottage in the yard so Elderly can have free homes….be close to Family and are not exposed to abuse in nursing….Government won’t allow it unless we All take Action to help our elderly who worked so hard to provide comforts for Us… …Children should take responsibility to care for them …It’s duty of family not to neglect elderly…who have saved to make sure their kids have a better easier life….please help in creating Laws in favour of Elderly….All these wealthy construction companies can pitch in…After all you cannot take any wealth with you……Remember HEAVEN lies beneath a mother’s Feet….
The oldest adobe (cob bricks & clay sand mortor) still standing and in use is over 600 years old by white mans stories. There are still in use communities and several abandoned cities and/or communities built by the pueblo and other southeast tribes used and kept up ie maintained for centuries as have the true mexicans, the indigenous native peoples of Mexico, who have also built adobe dwellings for at minimum over 900 years and still live in many of those that have been maintained! There are multiple abandoned communities all over central America and North America some maintained for historical reasons others left alone and crumbling without maintenance! When I lived in New Mexico we had an A-frame home my father built out of free lumber he sourced by tearing down or Well… helping to tear down 2 NMSU, campus buildings and built our home virtually for free! But we had already started on our adobe bricks, so he used our bricks to build a really awesome grill and oven for us to bake in and grill out on or do regular cooking just over wood fire instead of gas! That grill and oven was not under anykind of a protective awning or like a gazebo roof or the like there was none, but the entire time we were there it remained the same as the day we built it and yes it was fire proof that was for sure!! But it was good as rain after four years worth of use before we moved! It was just then getting ready for a maintenance coat!! Cob, adobe or whatever one calls it is amazing amazing amazing SUSTAINABLE & HEALTHY as well as being so beautiful and worakble in it’s plyablity!
Here is google first response to cob vs earthbags earthbags are considerably faster (think days, not months), much more moisture resistant (used for flood control), and don’t require a long curing time (cob can literally take years to dry out). But also, there’s the mixing. Cob and adobe are very labor intensive, and mixing is hard work.
As much of a non-environmentally friendly idea this is; if some company produced plastic roofs for cob and earthbag buildings we would see a boon in natural building. It’s the roofs that are tricky. The right plastic “lid” would make the process 1,000 times simpler and quicker. And the roof could be formed with beveled edges so sod could be put on it or a thatched Reed look. Dome roofs, traditional, hip, Victorian, mansard, you name it. With gutter systems molded into for rain harvesting. Daydream with me.
So is cob prone to deterioration when wet? It has the appearance of stone when dry but I notice the traditional shingled roofs which made me wounder why not have a cob roof? Stone roofs are amazing, so am I wrong in assuming that you need to keep the cob walls as dry as possible? And im curious as to how dry and for how long, can they get wet and for how long can they be wet?
Affordable… for who? The thing about cob building is the HUGE labour requirements to mix and build, there’s a reason main stream builders don’t use cob, its too labour intensive, ie unprofitable and unaffordable for any but the wealthy and/or those able to ‘host a cob building workshop’ and get people to pay you to do the work for you in exchange for “learning how to build with cob”. If you build yourself a small test project like a cob oven, you could figure out how much labour goes into sourcing the materials to make cob and how much labour it takes to mix the cob and how much labour it takes to build with cob. Then if you still want to build a house with 18″ thick walls, host a workshop, you’ll need the help.
I am sincerely doing research to build an underground home (I live in Canada and I want to build a home with pipes that won’t freeze) and there are 2-3 questions I’m trying to get answered. How do they build the dome roof? Where does plumbing/wiring go and what happens if you need to make repairs? Lastly, why domes and circles vs boxes and squares? I intuitively like it better, feels more natural, easier to heat I assume, but wood is a plentiful resource in my build site and I’m having a hard time justifying building in the round
I’m building a house with cob here in Mexico by myself ufa I’m 67 years old and it poops me out lol but poco a poco. Sure wish some one young would come down here for the winter and help me out lo. I’m using vástago de Palma then apply the cob over it. I want to learn more about plastering over the cob next. It’s warm her in the winter lol! I’m in Baja California Sur in a town called Todos Santos
OK, is the point of this that wattle and daub with “cob” is good? Fine, but this article doesn’t actually explain much, and cob wouldn’t really be that affordable for the average person. Where, other than forest land you own that’s far away from where you work, would you find branches and the needed sand clay and straw? You’d have to source them. Even the tiny amount the guy in this article is making is made from stuff bought at the hardware store. You still need lumber. You still need labor. If the point of this article is that you can build a cabin this way, congrats; building a cabin is building another building you don’t need. This article isn’t useful if they don’t go into detail on how to build a house with cob.
Unless you do it all yourself and invest all the time it takes (which you cannot monetize), it’s probably more expensive workforce-wise to build cob structures. The materials are cheap, but the cost comes up from excavation and transportation, unless a suitable site dictates you the place you must build. The point of modern materials is that they are mass-produced and made for easier assembly
If I don’t have access to having clay, what could be an alternative? Could I use a bag of concrete mortar? Could cob also be used just for siding on a house, as opposed to building a wall? I want to do two different projects, one for a shed/house and the other for siding my house. Would the cob stand up in cold Alberta weather for siding?
Thermal mass is not the same thing as insulation. In winter when there is inadequate heat from the sun reaching your cob walls, they’re going to remain cold all winter long. In cold climates you’re going to want insulation, not thermal mass, to keep out the cold. In summer, thermal mass will keep your house cool for several hours, but it needs time at night to shed its heat. If you’re in an uncomfortably hot climate where it doesn’t cool down very much at night, your house isn’t going to lose enough heat at night to make your days comfortable, and it may simply add to the heat keeping you awake. Again, insulation is what you really want. Straw bale construction provides insulation, not thermal mass. Cob is a building technique suitable only for relatively mild climates.