Cob Houses: A Simple Guide To Building A Cob House

cob houses


Even though I am busy building my own tiny house, I still find myself thinking about building a cob house… is that cheating on my tiny house?

I have been coming back to cob houses again and again because I love the curves of cob walls, the organic feeling that the cob mix brings and the price is also very attractive.  I have thought about building a cob house if in the future I decide I need more space if I get married or just want more space.

What Is Cob?

what is a cob house

Cob is basically clay, sand and usually straw mixed together to be used as a building material, kinda like bricks, but the advantage is that most of the materials can be sourced on site or purchased cheaply.  Having the right ratio of these three ingredients will let you create a study mix.  It’s basically like mud castles for adults, that is a building technique that’s been used for over 10,000 years!

Why A Cob House?

why choose a cob house

A Cob House is natural building material that has lots of beneficial properties that lend itself to a very comfortable home.  With the thick walls of the cob house, you have a lot of thermal regulation happening.  So in the heat of summer, the walls keep things cooler.  In the cold of winter, the walls can carry heat late into the nights.

Cob Lasts A Long Time

Cob is also very durable if it is properly sheltered from the rain.  A good roof will protect the walls and last for hundreds of years.  Even when the house has started to weather, you can actually re-apply a new layer of cob on to the outside to make it brand new!

simple cob house with lots of natural light

Cob Housing Is Affordable

Cob is also very affordable, in many cases all the materials can be found on your own land or can be obtained in large quantities for quite cheap.  You’ll need to do a soil test on your own dirt to see if it’s suitable for cob building, but in general most sites have some usable soil.

Cob Houses Are Pretty Fire Resistant

Because it’s mainly clay and sand, you don’t have much for forest fires to burn up.  Cob is a popular choice for areas that prone to wild fires or other extreme weather.

cob house with arched roof

Cob Houses Are Healthy

Creating a cob house often creates a very healthy home for air quality.  The one area you’ll need to spend some attention on is moisture levels.  Once you make your cob, it will need to dry out full and that can take months to years.  The bulk of the moisture will dry out of the walls in the first year, but will not fully cure for 1-2 years past that.

interior cob walls of house

Once you build the house and add a roof, you should allow it to breath for many months before moving into it. Then I’d do your internal sealing process. When you do move in, a dehumidifier will be important to draw the large amount of moisture out of the air.

Curved Walls And Round Cob Houses

The thing I love most about cob houses is the curves of the walls.  There is something so cozy, so appealing, so comforting about the curves in a cob house.  You can have these organic forms that allow elements just flow into each other.  It is hard to put your finger on exactly what it is about cob houses, but they have this magical quality that seems to resonate with some part of our brain.  I love it

How Do You Mix Cob?

how to mix cob the right way

The important part of cob is getting the mix right, you want roughly between 2 parts clay, 1 part sand, sprinkling of straw and a little water.  To mix these together the favorite method is with your bare feet!  I love the feeling of the cob squishing between your toes, so much fun!  You want the ingredients to be very well mixed, moist, but not wet and the straw well worked in.

The mix should hold its form solidly and not look like its melting or slump.  Make a test set of brick and allow them to dry.

Building A Cob House

Building A Cob House

A cob home has a lot of benefits, the one down side is that it’s very labor intensive and takes a good while.  Unlike traditional houses which can got up very quickly, cob is a slow process, so be prepared.

Set The Foundation For Your Cob House

No house is any good without a solid foundation to build upon and that goes doubly for cob.  Because your cob walls are so thick, around 24 inches thick, we are talking about a lot of weight.  Literally thousands of pounds of weight from the walls alone.  We want to have a good clear site to build the house.

cob house foundation

Start by clearing the top layers of soil to get to the solid base layer soil.  You want to dig down to below your frost line which can be 2-3 feet in some areas.  From there build your base with quality materials and tamp down with a powered tamper as you build your way up.

Consider water flow, so that water will be channeled away from the house site and any water that does come to the house can drain away quickly.  Use french drains and swales to handle this water.

Build Your Cob Walls

The walls in a cob house are super thick, which is what gives it’s strength.  Your walls will be thicker at the base and get thinner as they rise.  At the top, your walls might be around 18 inches, but your cob wall at the base will be 24 inches.  As you build, poke holes int the top of the wall to allow you to integrate the next layer into the bottom layer.

layer of cob mix to create a cob wall for the house

In general you can only build your wall 2-3 feet vertically at a time before you’re going to want to let it set and dry some.  This is an important step and is what takes so much time with cob.  Allowing it to dry will make sure the wall doesn’t slump over.

Windows And Doors In A Cob House

You can absolutely have windows and doors in a cob house.  The main approach here is to have a solid timber act as the header for the span of the top of the window or door.  Basically have a big beefy piece of wood at least 6 inches thick and go for as wide as the wall.

install of windows into a cob house

You want the header to cross the gap of the opening and then extend at least one foot on either side so it rests firmly on the top of the wall, transferring weight onto the wall.  The larger the span, the larger you need to extend your header to be supported by the wall.

Built In Cob Shelves, Stairs, Etc

Because you’re making the walls out of cob, you can form steps into the floor, you can have the cob flow so it has places to put books and other storage spaces.  You are also able to have wood stoves, fire places and other cooking surfaces part of the actual cob structure.

This is where your creative side comes out and you can work in beautiful curves, artistic elements and anything else you can come up with.

Sealing Cob Walls

plastering cob walls

There are a large number of natural ways to seal the walls of your cob house.  Various plasters, finished mud layers and white washes can all be used in the final stages of the walls.  This helps seal the walls and keep them lasting a long time.  It also lets you color the walls in artful ways.

Seal Your Floors

My favorite way is to do several finish layers of finishing mud and plaster.  From there, 5-10 coats of linseed oil applied directly to the dirt floor.  Finally come in and polish the floor with bees wax.

bees wax sealed cob floors

This approach brings a reasonably durable floor that is healthy from an air quality perspective, but also beautiful.  There is something so satisfying as that finished waxed floor rests under your bare feet.

What Can Cob Be Used For?

Cob is a great multi purpose building material.  Basically, most of what you’d normally build into a house, you can also build out of cob.  Cob has been used for thousands of years, so we have learned a few things about how it can be used in various way.  Here are a few of the big ones:

Cob Structures

Obviously cob can be used to build a house out of, but it’s also good to make other elements.  In the distant past, this was the building material of choice, so barns, well houses, out buildings, animal pens and storage buildings were all made out of Cob.

Cob Ovens

My favorite use of cob is building cob pizza ovens… because, pizza.  A cob oven can get to 800 degrees and is key to making a really good pizza.  It’s also really good for baking breads.  The oven is able to have a very consistent heat that also has some moisture to it.  This is way better than your home oven that has wild heat swings.

me building cob oven

Typically what I’ll do is get the oven heated up full, then put a little door on the front to let the heat fully soak into the mass of the oven.  From there I’ll stoke this a bit, then clean the bottom floor with a wet rag, making sure the coal bed is pushed to the back of the oven.

From there I’ll cook my pizzas which can fully cook in as little as 30 seconds!  I’ve been able to raise my small cob ovens up to 800 degrees for really fast cooking times that make delicious thin crust pizza.

After pizzas, I’ll toss in a few loafs of break to bake as the heat starts to tapper off.  I don’t add any wood, just let the heat bleed off, which it will still be around 500 degrees at this point.

Finally I pull the bread and slide in whole chicken, a beef roast or other large meat with vegetables.

Rocket Mass Heaters

A rocket mass heater is just a high efficiency wood fire that the heat is piped through a large mass of cob and sometime rocks.  The cob will heat up and the larger the mass of the cob, the better.  This is usually done as a cob bench, which allows you to have a useful large mass in your house.

bench in a cob house with a rocket mass heater through it

Cob House Tours

cob house tours

Here is a collection of some of the best cob house tours I’ve seen.  Take a look at these video tours:

Cob Design Inspirations

cob house inspirations

One of the wonderful things about cob homes is the ability to have a lot of artistic flair to them.  The natural curves of the house are one of the best features of cob homes.  Here are some photos for you to get some design ideas for your own cob house.

Cob house interior

Cob houses can be big and 2 stories

cozy bedroom in cob house

use a rocket mass heater to heat your cob house

organic shapes for handmade cob house

natural curved cob stairs

Cob house interior with wooden beams and stone floor

cob house exterior

  1. Hey, one of those places is my neighbour’s house! It’s a fantastic place, very comfy and good in all weather. It was built before I got my place so I didn’t get to see the process but I’ve heard lots of stories. If I was building a permanent structure I’d definitely consider cob, for both practical and aesthetic reasons. The heated cob bench is amazing on a chilly day.

  2. If you want a great exchange/apprenticeship go to
    and attend a stay building innovative cob houses,thermal mass rocket stoves,etc.
    Wonderful group of people!

  3. Ryan, I totally understand. I think about natural built houses all the time and we haven’t finished out the interior of our Tiny House yet! Natural built homes are so beautiful and we would have built this way had we had land to build upon & the money to buy the land (we decided not to go in to debt again and opted for the tiny house on wheels instead).

  4. What do you guys think of a tiny cob house on wheels? So building a cob house on a trailer? Do you think it would crack going over a speed bump? I really really want to do this but haven’t found any information about cob houses on wheels … is it too heavy? Thank you for your input!!!

    • I also have the same question!

    • i would imagine it would crack (because of all the bumps and yes it would be to heavy 🙁

    • I don’t believe that you could put a Cob house on wheels because of the weight.

  5. I love the Cob house. Am building in franklin tenn do you have plAns for your cobs? Lovely

    Genie akin

  6. Hello.Please share the already constructed cob houses, the challenges encountered and solutions. Thank you.

  7. I have a couple lots in CharlotteCounty,Florida. Would this be a good thought to build a couple??

  8. What is the difference between cob and adobe? I live in an adobe house with cement floor.

    • I think adobe is generally made with sun hardened bricks & cob is built up with wet clumps, allowed to dry some, built up some more, & so on.

  9. Can cob houses have basements? I don’t think I’ve ever seen over with a basement…

  10. How can I find a Natural Builder to hire, so they can build a cob house for my family? I need an expert. Thank you.

  11. Oh we are planning to build a tiny cob house. Just waiting eagerly to start and your message above is very helpful. Thank you ☺️

  12. Excellent article, I need to truly improve the content I have.

    I have attemptedto blog on third part platforms,
    it just did
    not transpire just how I wanted it to. But your website has
    providing me a hope to achieve this. I shall be bookmarking your website
    and checking it out from time to time. Many thanks!

  13. Is there a natural builder with experience building cob homes that I can hire to help me build a couple of cob homes on my land?

  14. Can this cob house be built in Panama in the mountains where it rains a lot in the winter?

    • It’s a good question. I have heard there are examples of old cob houses in England, where the weather gets wet and freezing. I have never built or tried to build cob before, but that might be a direction to research in. Panama is a tropical climate though, so it might be more difficult for the cob to dry because of the humidity, but I hope you can find a way.

    • You can built a cob house in any climate. I have seen lot of mud houses in the tropics where it rains a lot and very humid. Give it a good extra high basement and a expanded roof like a cap around your outside walls, and it’d have a long life.

  15. You can build a cob house anywhere.
    But you have to consider the quality of the clay in the area.
    Usually if you dig, that clay will be used to build the walls and you’ll have a cellar as well.

  16. How would I go about getting a permit for building a cob home in Meade County Ky? I’ve tried contacting a couple real estate agencies here but so far they never heard of the material. Any help or advice would be appreciate.

  17. Thank you for your lovely and useful article.
    Could you please advise me on the best way to plaster the cob house walls? A light mud with something ?
    Thank you!
    Dina Yardley

  18. Wonderful! So inspired, I have a homesite and am so looking forward to being able to build. Thank you for sharing your experience and projects.

  19. Extremely interesting. But I live in Europe and you are probably an American/Canadian company. Do you do business in UK or France?

    Everywhere I read of cob, it is always claimed that cob is cheaper than conventional houses. Do you have any confirmed numbers? It isn’t easy going to the bank asking for a loan for a design of little known technology.

    Are these wonderful interiors designed in forehand, or is the final touches pure ad lib?

  20. This is cool. Just wish I had more time to build one! Would be great for a new spa!

  21. Superbly inspiring information. I’m off to attend a cob, Adobe building workshop in the Himalayas after this.

  22. wonderful, i would love to learn more about this

  23. That’s great and lovely

  24. Greetings ttl, thanks for this wonderful insight into the cob world. I am now a great fan and would love to have your guide to cob house building and any other information about cob house building.
    Thanks as I look forward to your positive response.
    Kind regards, Chidi

  25. This is awesome! My dream is to build a cob house and have a decent garden with honey bees <3

  26. Thank you very much for sharing this valuable info. I
    live in the Caribbean and is thinking of building a cob house.

  27. Love this, can a cob heater be used to heat a swimming pool?

  28. Love this, can a cob heater be used to heat a swimming pool?

  29. Where do I get plans to show to get a permit to build?

  30. commin up on 58 years old. Nothing in the bank for later. I need a Cobb house. These are way cool but a 1 person place would be great. Any references?

  31. Wow, loved each and every place I look at.What states are good to have a cob home in? I live in Michigan and are weather is rain snow heat cold ect.

  32. I am interested in cob house
    How can I physically talk to somebody in person

  33. Absolutely beautiful. My dream is to build a cob house one day. Thank you for all the brilliant ideas I learnt from this publication.

  34. What kind of soil test do you need to make cob? What composition are you looking for?

  35. What part of the US is best to Build
    i would love to build a few COB CITY

  36. How can I make the structure for a cob house? Do I first need some kind of wooden structure to use as support? And when is that applied – before the building itself, or as we go… I can see in these videos pieces of wooden structure coming out – is that done during the proces? Do I need an architect for this? Can I build the whole thing myself?

  37. How can I make the structure for a cob house? Do I first need some kind of wooden structure to use as support? And when is that applied – before the building itself, or as we go… I can see in these videos pieces of wooden structure coming out – is that done during the proces? Do I need an architect for this? Can I build the whole thing myself?

  38. How can I build a cob house by myself without any help? Is that possible? I would be prepared to invest 5 years in the project. If it’s possible, do you have any tips? I would also need to go to one of your workshops maybe?

  39. Wow! want to build a cob home soon.

  40. I enjoyed this article, very informative and with photos to delight the senses, thank you, I feel closer to be able to making something out of cob, a dream a have been entertaining for quite a long time. First I want to create a little playhouse for beautiful girls, then a small house 🤞🤞🤞

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