How To Make Cob – Step-By-Step Guide for Beginners
How to make cob is easy and quick if you have the exact knowledge from experts. Collect the required material, followed by adding water in a pre-set proportion, and mix it with your hands and feet. Keep on mixing until it is good or the consistency you need.
Cob is an antique/old material used in the construction purpose buildings. This material has a rich history dating back thousands of years. It is a mixture of clay, sand, and straw and has been used in construction for its durability, thermal properties, and sustainability.
Cob is a well-known material, but it is rarely available in ready-made form. So, those who use cob for their projects tend to make it from scratch.
In this article, we will give you a thorough guide on how to make cob step-by-step. So, you can explore this traditional technique and potentially use it for your building projects. But let us first tell you what cob is.
What is a cob?
Cob is a classic building material that uses a mixture of earth, sand, straw, and water to produce durable and sustainable structures. It is an ancient building method that has been employed for centuries in different parts of the world.
Scope of Cob Making
This is famous, particularly in regions where these materials are available in greater quality. In today’s modern world, people are still using cob for different construction projects, including cob bricks, cob houses, and outdoor oven construction.
Cob Making Machines
There are cob-making machines available that help people make their work easy and make cob for commercial purposes. On the other hand, in rural areas, where resources are limited, underprivileged people make it on their own to meet their needs.
Cob Construction
In cob construction, the cob mixture is made by mixing clay-rich soil with sand. Straw or other fibrous materials are added to act as a binding agent and provide strong strength. Water is then added to the mixture to build a workable consistency.
Cob Mixture
The cob mixture is generally formed into large lumps or balls, known as cobs, and these cobs are then piled up on top of each other to build walls. The walls are built-in layers, and each layer is left to dry and harden before the next layer is added. This process allows the walls to take shape and gain strength slowly.
Cob Properties
Cob constructions usually have dense, thick walls, providing incredible thermal mass and insulation properties. They can benefit from controlling indoor temperatures, which keeps the interior cool in hot weather and warm in cold weather. Cob structures also tend to be aesthetically pleasing with organic figures and raw textures.
Benefits of Cob Construction
One of the advantages of cob construction is that it uses locally available and sustainable materials. It is also a relatively inexpensive building method, as the materials are often free or inexpensive.
Skills needed for Cob Making
Cob building requires skilled craftsmanship and knowledge of the materials and techniques involved. However, it is a fine technique that can be used to create a variety of structures, including houses, cottages, studios, and garden walls. With proper maintenance, cob buildings can last for many years.
Materials Required To Make Cob
- Clay: Look for clay with high clay content. Clay can be purchased from ceramics suppliers or dug up from your own land if it contains suitable clay sediments.
- Sand: Use sharp sand or a mixture of sand and pebble. Avoid using fine sand, as it may dilute the cob.
- Straw: Go for long straw fibres, such as wheat or barley straw, which will improve the strength of the cob.
- Water: Sufficient water is needed to achieve the right consistency for mixing.
Step-by-Step Guide To Make Cob
Prepare the Clay
Dig up or collect clay from your land, or you can purchase it from a supplier. Remove any harsh rocks or or debris that can disrupt the texture of the clay. Break the clay into smaller pieces and allow it to air dry for some days. You can also accelerate the process by spreading it under the sun to dry.
Prepare the Sand:
If you are using harsh sand, no extra preparation is needed. If your sand contains larger particles or gravel, filter it through a mesh to remove any oversized material.
Prepare the Straw:
Collect long straw fibers, such as wheat or barley straw. Remove any seeds or debris from the straw. Cut the straw into small pieces (around 2-4 inches in length) to simplify the mixing process.
Mixing the Cob:
Start by measuring the quantities of clay, sand, and straw. A common proportion is about 1 part clay, 2 parts sand, and a handful of straw for every 4 parts of the mixture. Scatter the sand on the mixing area and make a well in the very center.
Gradually add the clay into the well, breaking it up and mixing it with the sand using shovels or spades. Add water in small quantities while mixing the clay and sand. Intend for a consistency similar to bread dough (moist but not overly wet). Once the clay and sand are well mixed, add the straw and continue mixing until it is evenly distributed throughout the cob.
How to make a cob without clay?
There are a few circumstances where clay may not be available. Although traditional cob commonly consists of a combination of clay, sand, and straw. Where clay provides the binding properties necessary for the cob to hold its shape. However, if you don’t have clay, you can still create a similar building material using alternative ingredients. Here’s how you can make cob without clay:
Materials:
- Sand
- Soil
- Straw
- Water
This is how you will begin making cob without clay. Start by collecting sand. Look for clean, sand-free from debris and large size gravels. River sand or construction sand is usually suitable.
Search for soil with much clay content. Even though it might not be pure clay, soil that contains a significant quantity of clay will help to give some binding properties. Clay-rich soil is frequently found in agricultural regions, digs, and riverbanks.
- Mix the sand and soil together in a ratio of around three parts sand to 1 part soil. Adjust the ratios according to the consistency that is required.
- Slowly add water to the mixture while thoroughly mixing it. You need consistency, the same as dough or mud. The water will help the clay in the soil and bind the sand particles together.
- Add shredded straw to the mixture once the sand and soil are well mixed and have the desired consistency. The fibers will support to strengthen the cob and also remove the fear of it cracking.
- Knead the mixture well enough and make sure that the distribution of straw is even. This will help in improving the quality of the material.
- Now, test the cob by shaping a small sample into a ball or a small brick. Let it dry for a few days to check if it holds its shape. You might need to add more water or fibers to the mixture if it crushes.
Once you’re satisfied with the consistency and binding properties, you can use the cob to build walls, ovens, or other structures. Use the cob in layers, allowing each layer to partially dry before adding the next layer.
Remember that a cob made without clay might not have the same strength or durability as a traditional cob. It’s important to consider the requirements of the purpose for which the cob is needed.
FAQs:
How do you make cob mix?
Cob is a mixture of soil, sand, straw, and water. You merely need to add all these elements together whilst adding water gradually. Once you have a thick consistency, knead the cob well. You can also use a mortar mixer to mix the cob.
Can you make a cob without clay?
Yes, you can make a cob without clay. In place of clay, you can use soil that has clay properties. A clay-rich soil, which consists of both sand and silt and other materials, can be used in place of pure clay.
How do I waterproof my cob?
To make your cob waterproof, it is recommended to use boiled linseed oil. Coat your cob with the linseed oil and it will protect the cob from water.
What is cob made from?
Cob is typically made of components like clay, sand, straw, and water.
Conclusion
Learning how to make cob isn’t as hard as it seems. Simply collect the required materials and jump into the process of cob-making. Cob has been used as a building-making material for ages. This material is not only easy to make but is also long-lasting. The elements used for cob-making are almost easily available all around the world.
These elements serve as the binding purpose and reinforce it. However, the main component of cob clay might not be accessible to everyone looking to make a cob. Nonetheless, there are substitutes that you can use in place of clay.
