About Us

A young lady building a cob chimney

About Building with Cob

Building with Cob: Warm, Natural, Inviting.

There’s something about the smooth, hand-sculpted forms and the natural, earthy appearance that gives cob structures a feel – almost a “presence” – unlike anything else in the built environment. This quality alone, in addition to its amazing durability and thermal mass properties, would be enough to make us choose cob as our favorite building material. But just in case that’s not enough for you, here are a few more good reasons to choose building with cob.


Building with cob encourages us to use locally available materials, most of which can almost always be found within a 5-10 km range of your project.

The earth component can often be found just below the topsoil on your property! If not – there is almost always some nearby roadwork or some other construction project which would be happy to give you all the clay-rich soil you want for free. The straw component can be purchased from a local farmer for a few dollars a bale (if you don’t already know a farmer, you now have yet another reason to work a trip to your local farmers market into your weekly routine)! The sand component – if not already in your subsoil – can be purchased cheaply and without hassle from any nearby quarry.


Whether it’s an adobe floor, a cob wall or an earthen plaster project, the primary ingredients the same: clay, straw and sand. The only difference is the ratios of each ingredient and the overall quantities. The good thing to remember is that, whether it’s a little or a lot, all ingredients occur locally and naturally – which means low processing and even lower embodied energy.

Earth also has excellent thermal mass properties, so it naturally moderates indoor temperatures by storing heat during the heat of the day and releasing it back into the environment during the coolness of night. This unique property makes cob, earthen floors and earthen plaster perfect building materials to choose if you are interested in designing a passive solar house.


All of Fermata’s building materials – even our silicate mineral paints – incorporate 100% naturally occurring materials, with our guarantee of no off-gassing chemicals or toxins – unwanted (and often ignored) ingredients which are commonly found at high levels in modern building materials.

In addition to a healthy physical nature, the gentle curves and flowing forms of earthen construction – it’s “presence” – naturally create a comforting, friendly environment. Indeed, studies have suggested that earthen construction in the built environment can significantly reduce stress levels of a building’s occupants, thereby improving both mental and physical health!


Cobbing has been aptly referred to in the literature as the construction of “hand sculpted homes”. The same could be said about adobe floors and earthen plastering. No other building technique offers such an intimate, almost spiritual connection with the building material – encouraging you to literally “get your hands into it”. In our opinion, no other form of construction is as artistic or as inspired.

Owner Participation

We love what we do. We love it so much, we’re sure you will love it too.

In fact, we’re so sure of it that we want to encourage you to participate. What better way for you to gain that intimate connection with your living space than for you to help build it? Earthen construction is extremely hard work, but the material is forgiving and the rewards are immense. Contact us to find out how you can be involved!