How To Make Cob: All You Need To Know

If you have only just now heard of cob and are wondering what it is and how it could possibly be turned into a house, then you should read this article. 

You will learn that one of the many great aspects of cob homes is their capacity to have a lot of creative flare.

How to Make Cob: All You Need to Know

One of the nicest aspects of cob dwellings is their natural curves.

If you are wanting to build a resourceful, sustainably, and beautiful home – then this guide will help!

What Is Cob?

Cob, sometimes called cobb, is a type of construction material made out of clay, straw (or another fibrous organic material), water, and sometimes lime.

Cob construction, unlike straw bale and adobe construction, does not employ dry bricks or blocks. Instead, wall surfaces are constructed from moist cob mixture lumps that are squeezed and moulded into smooth, sinuous patterns.

A cob house is one of the most long-lasting forms of earth construction. Cob can resist prolonged periods of rain since the mud mixture is permeable.

To protect the outer walls from wind damage, a lime and sand plaster might be employed.

Cob architecture is suited for the desert, and some believe it is even suitable for very cold climes – walls may be two feet thick, especially at the base, above the foundation.

Small cob constructions, such as tiny dwellings and garden huts, are low-cost DIY projects.

How To Make Cob

The most crucial aspect of cob is getting the appropriate mix, which should be around 2 parts clay, 1 part sand, a dusting of straw, and a little water.

To do it the traditional way, you can combine the mixture with your bare feet.

Stamp the mixture until it is thoroughly combined and has a texture of being moist but not wet and the straw has mixed in.

However, if you prefer to adopt a more modern method of mixing, you can use a portable cement mixer instead, which conducts all of the labor-intensive mixing of the clay, sand, water, and straw, is the simplest way to build cob.

The mixture should retain its shape and not appear to be melting or slumping.

Make a test set of bricks and leave them aside to dry.

In many places of the world, clay is a plentiful natural resource. It is cheap and has been used to construct “mud cottages” from the beginning of building.

Because clay has varying moisture percentages, different quantities of sand are utilized to make cob.

Straw serves as a fibrous binder. To construct a cob wall, balls of the mixture are tossed together and moulded over a pre-built base — a foundation that is often formed of stone and rises a foot above grade.

How To Build With Cob

Cob is an excellent all-purpose construction material. Basically, you can create much of what you’d ordinarily build into a house out of cob.

For thousands of years, cob has been used to build homes, which means that over this time we learnt a few things about how to use it in different ways.

Here is a brief step by step guideline on how to build a cob house. 

Start With The Foundation

No home is good without a sturdy foundation to build on, and cob is no exception. Since cob walls are generally very thick (about 24 inches), they will also be very heavy.

This means that they need a good, sturdy foundation to give it the most support. 

Begin by removing the top layers of soil to expose the firm foundation layer dirt.

You should dig down to the frost line, which might be 2-3 feet in certain regions.

Build your foundation with excellent materials and tamp down with a powerful tamper as you work your way up.

Consider water flow so that water is diverted away from the home site and any water that does come into contact with the house may drain rapidly.

To handle this water, it is best to use French drains and swales.

Build The Walls

The walls of a cob home are quite thick, which lends it its strength. The walls will be thicker at the bottom and thinner as you climb. 

Usually, the walls will be 18 inches tall at the top, but the base will be 24 inches tall.

Poke holes in the top of the wall as you construct to allow the following layer to be integrated into the bottom layer.

You should build the wall 2-3 feet vertically before letting it set and dry.

This is a key phase that takes a long time with cob. Letting it dry will prevent the wall from collapsing.

Install Doors And Windows

You can even add doors and windows to your cob building to make it really feel like home.

The fundamental method here is to use a solid timber as the header for the whole span of the window or door’s top.

Basically, you want a huge meaty piece of wood that is at least 6 inches thick and as broad as the wall.

The header should pass the aperture and then extend at least one foot on either side, resting solidly on the top of the wall and transmitting weight onto the wall.

The bigger the width, the longer your header must be to be supported by the wall.

Build The Interior

Because the walls are made of cob, you can make stairs into the floor and have the cob flow so that there are spaces for storage. Wood stoves, fire areas, and other cooking surfaces can also be built within the cob construction.

This is where your creative side shines through, and you may use gorgeous curves, artistic motifs, and everything else you can think of.


There are several natural methods for sealing the walls of your cob house.

In the final phases of the walls,completed mud layers, various plasters, and white washes can all be employed. This aids in the sealing of the walls and their long-term durability.

It also allows you to color the walls in artistic ways.

One of the preferred methods is to apply multiple final coats of finishing mud and plaster. 5-10 applications of linseed oil were then applied straight to the dirt floor.

Finally, use beeswax to polish the floor.

This method results in a floor that is not only moderately durable but also healthful in terms of air quality.

There’s something so wonderful about having that polished waxed floor under your bare feet.


Cob is a building material which consists of clay, sand, and straw which is then mixed together to create cob. 

Cob was first used in 13th century England and a popular theory is that it evolved from the same mud mixture found in Medieval times used to mortar stone walls and fill in holes between stone faces. 

Even to this day, cob is still used to build houses not only in England, but all over the world.

There are many reasons for this. One of which is that cob buildings are great for insulation.

So if you live in a cold climate or warm climate, the temperature will be kept consistent and comfortable. 

Another great thing about cob is that it is easy to come by and if you put in the research and work, you can make your very own cob house. 

Joel Adams
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