What is Cob?
Cob is a natural material used to build houses, barns, and smaller structures. Cob is made of earth (subsoil), water, fibrous organic material such as straw, and sometimes lime is mixed in. You mix this natural material with your hands and feet to form lumps of earth mixed with either sand or straw. It’s an easy construction to learn and one of the most inexpensive forms of building
A cob house is cool in the summer and will remain warm in the winter. Cob is resistant to rain and cold conditions. As well as resistant to dry and humid conditions. Alternative building methods that use earth to construct homes are 100% recyclable, non-toxic, require no special equipment, and use only natural, sustainable materials.
The basics of building with cob.
1. Compress the land.
Even out the dips in your building site and make sure there are no soft places that could possibly sink in. Once the house site is compressed, cover it with a layer of sand to ensure the building site is even. You want a flat, smooth surface to begin.
You could build a concrete foundation all natural is better. Simply form a cob floor. Cob is durable once dried. You can paint it or sprinkle sand on top of the floor and seal it and it will be skid proof. There are many different options and different designs when building using cob construction.
3. Mix the cob.
Once your main ingredients are mixed. Pull out the longest pieces from straw bales and mix together with the mud mixture until you form balls that do not flatten out when dropped.
4. Build cob walls
After mixing, form lumps and add a handful at a time, forming a wall, smoothing out and shaping as you go. You will want to make sure the wall is the same thickness from bottom to top so it doesn’t thin out at the top leaning inwards. You can work on building a cob house for months. You can add wet cob to dry cob and it will bond, unlike concrete.
5. Doors and Windows
The best option is to form both windows and doors using frames. You can sink wood directly into the wet cob. The wet mud mixture will not destroy the wooden frames. The cob will dry causing no harm to the wood and giving you a strong frame. You can then fit suitable doors and windows.
6. Special Additions
This is your cob house. Make it as personal as you desire. You can build an oven out of cob. You can build and shape your own nooks and crannies to store your books or other items. You can form bookshelves right into the cob walls. You can shape shelves into the wall to display your personal belongings. You can even add staircases. Make the stairs straight, curved, or they can also be built right into the wall. You can be as creative as you want, add your own personal touches. This is your cob house, your home.
At the top of each cob wall, you can form a roof with wood or beams. It is your choice on how to construct your cob house’s roof. Whatever you choose, tin, mud, solar panels, etc., be sure the roof will be able to hold up against the weather and elements of your site location.
8. Almost finished
Did you know you can paint cob once it dries? You can paint the interior and exterior of your cob house any color you choose. Build a cob barn or coop on your land to match your new cob house. Stick with being eco-friendly and green. Raise your own animals and build a huge garden.
You are probably wondering about hygiene and electric. During construction, when forming your cob walls is when you will add in these functions. If you want electricity or plumbing, simply build the pipes or wires into the walls. The cob will not harm them in any way. You may need to add insulation depending on the climate. You can also add insulation when constructing your home. If you want these features, do not forget to add them as you are building. You would not want to destroy your home and rebuild it if you forget to install something important.
Alternative Building Methods
There are other ways to build sustainable homes that are made of natural materials beside using cob construction.
• Strawbale- Stack strawbales and finish with plaster or earth.
• Logs- A popular and beautiful structure, a log cabin. A house built using logs.
• Adobe- A clay brick method similar to cobconstruction. This a hard and laborious form of construction. The clay brick mix is similar to concrete. Once, you form the bricks and they dry. You will then build your structure. Not an easy task depending on the size of the clay bricks.
• Rammed earth – Soil that is compressed into a mold.
There are countless other methods as well. I’ll stick with building a house using cob construction. A cob house is sustainable, fireproof, the walls have a high thermal mass to keep warm in cold weather and stay cool in the hot summer. You may need to upkeep the exterior walls every decade or so due to rain. Or you can simply buy a waterproof stain to cover your house with to prevent the rain from wearing down the walls if you are in a place with constant, heavy downpours. On the contrary, cob houses are made to last. Homes built using cob construction will withstand the wears and tears of time. After the construction is complete, the cob house will last for generations to come.