Even with many looking for luxurious accommodation with all the latest technology and amenities, the trend is moving slowly towards off-grid living. From mobile homes to prefab tiny houses, we’ve seen people online enjoying life living in these. But have you encountered cob houses?
You build a cob house with clay mixed in between sand and straw, which provides an eco-friendly profile compared with traditional and synthetic materials such as brick and stone.
This article explores various benefits and disadvantages of a cob cottage. We also give a brief explanation of how to build your own home.
A cob house is a tiny house made from a mud mixture of clay, sand, and straw bales. Cob is an ancient natural building technique used in northern Europe, parts of Asia, Africa, and America. Unlike other mud houses that use dried-up brick, cob construction uses wet lumps of cob.
You can build cob walls without a supporting building material, like wooden frames and concrete pouring. It is why a cob house has curvy frames and arches.
A cob house is one of the most durable types of architecture. It is a building technique suitable for people living in arid and mildly cold climate regions.
If you are wondering why a cob house? Here are seven benefits of building cob homes:
Cob homes are great because they have thick walls with high thermal mass, which provides more energy efficiency than modern homes.
The building material, cob, absorbs and stores heat during warmer seasons. It releases the stored heat during colder climate conditions, heating the interior part of the house.
They can absorb solar radiation during the day because of their high thermal mass. It promotes energy efficiency because you don't need central heating systems like air conditioning units and rocket mass heaters. Less energy used means lower energy bills.
One of the most important benefits of making cob houses is its sustainability. You can find some materials used to make cob (clay and mud) on the building site. You can get the other building materials (sand and straw bale) at local stores.
The process of getting these materials does not harm the environment, unlike the modern materials we use for building. Due to the easy sourcing of materials on site, building cob homes has a low carbon footprint.
Furthermore, there is no need for heavy transportation of materials or industrial machinery, which reduces environmental pollution and the energy used for construction.
Building a cob house is less expensive than building a modern home. The materials necessary for building are readily available in the natural environment. They are also low-cost in most locations. Most times, the owner builds their cob home themselves.
However, it can be expensive for people who outsource the building labor instead of doing it themselves.
Your cob home has more protection against fire disasters than modern buildings. The materials used for cob, clay, and sand are naturally fire-resistant.
Another benefit of owning a cob house is its durability. A cob house built correctly can last over 100 years in proper condition and with regular maintenance.
In fact, old cob structures are still available all across Italy, Europe, and Africa. It can survive earthquakes and other natural disasters that destroy modern houses.
Also, cob house construction gives enough room for self and artistic expression. You can build your cob home in any desired shape. Most cob houses have curved walls, drawing on the walls, and circular window and door frames.
You can also use cob to create furniture, ovens, and shelves. It allows free expression through any creative means. It is what makes cob homes unique.
Construction of a cob house can be very time-consuming. Local community members and friends can help you build. It reduces labor costs in time and money. It also creates a sense of unity within the community, promoting social sustainability.
Constructing a cob house takes a lot of time and labor because each layer of cob must dry before you apply the next one. Depending on the size of your cob house, construction can take up to 15 months before it's complete.
So, take note of the construction time before you start building. Cob house is not the best choice for someone looking for a quick construction method.
Also, you might hire a natural builder to help you with construction. To build a cob home, you need some necessary construction skills. It is better to hire an expert, but it is expensive labor. However, you can take cob building courses to learn how to build comb homes.
Refrain from attempting to use cob in areas with cold or wet weather. Cob breaks down after consistent interaction with water. However, you can manage it with a good roofing system.
Getting the necessary permits to build cob houses takes time and effort. It isn't easy because the cob building doesn't meet either traditional build code requirements, and the bodies that grant the permit are not used to handling non-traditional homes.
They will readily accept a house built with synthetic and industrial-formed materials rather than a cob house. It is best to get a permit before making building plans.
After learning the pros and cons of a cob house, you’ve decided to build one. Here is a mini guide on how to start living more sustainably:
Related read: Sustainable living skills.
Cob building is an ancient building technique that isn’t common in our modern world. It is not an acceptable building technique in many parts of the world, especially in North America. So, you need confirmation from your local government if building a cob house in your area is okay.
Although the cob building was recently approved for inclusion in the International Residential Code as Appendix AU in 2021, you will still need local permits to construct a cob house.
Some areas do not allow the building of homes labeled off-grid homes. It refers to houses not connected to the electrical grid. However, some regions now use the term to refer to houses built without using modern house-building techniques. But you can construct a cob house freely in some rural areas.
Once you get a building permit sorted, pick out the section or land area to build your cob house. It is best to pick a parcel of land with an even, flat structure for cob construction because it makes building easier.
However, don’t worry if your land has uneven terrain. The good thing about building cob houses is how they follow bumpy terrains.
Draw a house plan to suit your preferences and the land you are building on. It is best not to build cob houses in flood plains because cob is highly susceptible to water damage from extended exposure.
Before building on your land, you need to clear the land. Remove overgrown bushes and unwanted hills. Fill up the dips and ditches to create even floors. You can compress the area by using a roller device.
Once the land is ready, it is time to lay the foundations of your own cob house. The ancient methods of building cob houses used a stone base as the foundation. The stone base makes a great foundation because it protects the bottom of cob structures from moisture or flooding.
Since we live in a modern world, you can use a poured concrete foundation to build a modern cob house. It is crucial to dry the foundation before you continue building. For this reason, it is best to build cob houses during the warm and dry season.
You can’t build a cob house without preparing the cob mix. Place a tarred canvas on the area designated for mixing cob. Add two parts of clay to one part of sand. Then, add some water and stir to create a suitable cob mix. Stirring them with your bare feet is better to get an even mixture.
You can wear mud boots for protection if you loathe the feeling of mud between your toes. While mixing the clay and sand, add some pieces of straw to the mix. It is best to pick the longest straws from the straw bale because it adds more structure to the cob.
The cob mixture is ready when it doesn’t stick to the tarp. Add more straws until the mixture forms a ball and doesn’t become flat when dropped. An improperly mixed cob reduces the durability of cob houses.
There are a lot of factors to consider when creating the interior walls of a cob home. You need to consider the framework of the doors and windows, the plumbing, and the thickness of the walls.
Cob walls must be arranged evenly for adequate weight distribution. When building cob homes of two to three stories, the walls must have a minimum thickness of 23 inches or more to support a second and third story.
Break off smaller mounds from the cob mixture to form cob walls. Press the small lumps with both hands to smoothen it and create a long, slim piece. This thin piece isn’t the final form to begin the building process. Stand it on the small end, push, and fold until it becomes short and fatter.
You are to recreate the shape of a small clay brick with your hands. You can use a ruler to measure the width of each cob lump to ensure they all have the same width. Layer the cob upwards from the stony foundation. Poke holes at the top as you add new layers.
Cob dries as you build, but it is not a problem. Adding new layers of cob to the dry layer helps it bond better. So push the new wet layer of cob into the old, dry layer with bamboo sticks or dowels.
As you build the walls, leave allowance for electricity by laying some conduit pipes. Also, leave room for plumbing in the kitchen, bathroom, and toilet. In addition, you can incorporate shelves by cutting the cob wall with a harmer or butter knife, depending on the thickness of the walls.
By the time you get to the door and window areas, you should have your window and door frames ready. You’ll want to create the doorways around the door frame. Sink it into the cob and continue building around it to make it secure.
You might need to add protruding nails and screw to the frame so the cob has something to hold on to. You can use a natural re-bar to ensure they are correctly attached.
At this stage, you can add uniqueness to your cob home to reflect your tastes. You can add rocks to the walls to create a unique look. Add your bookcases, cabinets, and shelves to your home. You can also build a straight or spiral staircase.
Start constructing the roof once the walls are ready. You can do this by sticking wooden logs and poles into the top of the walls. You can have a thatch, tarp, or solar panel roof. You can make a good roof out of natural materials.
Once you're all done, add a decorative and protective sealant to the interior and exterior walls to give it a smooth texture. You can decorate cob houses however you want. Some people opt to paint it, while most leave it in its natural state.
Investing in a natural building style is one of the best ways to spend money on housing. Cob homes is a natural building construction that benefits you and the environment.
Although cob construction takes time, it is affordable and saves energy. You can build many other things with cob. You can construct a cob oven, fireplace, and furniture.
A cob cottage is a great housing choice for someone living on an organic farm. You don’t have to spend a lot on energy bills. You can invest in solar power to sort out your other energy needs. Remember to take a course on how to build a cob house before you start building.
Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.
Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.