The Eco-Friendly Building Method You’ve Never Heard Of

by Steve Graham, Networx

Cob construction is like shaping a house with artists’ clay but never baking it. Cob (which borrows an Old English word for mound and has nothing to do with corn) is a mass of straw, clay, sand, and water. In a gradually reviving form of construction, it is hand-sculpted into buildings while the mixture is still wet.

Cob construction may be the world’s most environmentally friendly building process. There are no additives or chemicals. No energy is consumed in heating or forming the material, and no heavy machinery is required. In the right areas, the basic building materials all can be obtained locally.

Cob was used for many years in Europe, and is still widely used in Africa. Many European earth structures are still standing despite centuries of rain and harsh winters.

It is closely related to adobe, a popular building style in the Southwestern United States. The main difference is bricks. Adobe uses sun-dried earth bricks connected with mud mortar. Cob construction is a simpler concept, but takes detailed planning. Here are the first steps of cob construction.

Choosing a Site

The most important factor is drainage. Cob will break down if it is submerged. Make sure that even a 1,000-year flood won’t saturate your cob walls.

Instead, build on a hill to ensure good drainage. Cob works well on sloped properties that complicate standard frame construction. Also look for full sun exposure in the winter, and land with available clay soils, if possible.

Designing the House

Spend plenty of time designing every inch and each curve of a cob house. Make a scale model of the house, including surrounding trees and landscape features. Without four-foot sheets of drywall and other pre-measured supplies to confine the project, much of the house can be as creative as your imagination.

Thoroughly consider lighting and insulation. Take advantage of natural solar light and heat, and design thick walls with embedded straw-bale insulation where needed. After creating a design and consulting with cob experts, obtain the proper building permits (even though very few municipal housing codes explicitly cover cob construction).


You can’t just buy cob mix at a home improvement store, but you may be able to creatively find the materials for free or really cheap. All but the richest agricultural soil and rockiest mountain landscapes have some mix of sand and clay. If either material is not immediately available, look for road projects or construction sites where they may be looking to get rid of clay and sand. Farmers often sell cheap straw bales. As long as the straw is not rain-rotted, it should hold the sand and clay together nicely. With materials in hand and a model of the house, you’re ready to build.

Cob construction is an old, simple and environmentally friendly building technique that is new to most of us. For cob building workshops and classes, and other information, visit the Cob Cottage Company. “The Hand-Sculpted House” by Ianto Evans, Michael Smith and Linda Smiley, is a detailed cob construction handbook that provided background information for this article.

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William C
William Cabout a month ago


Johnso R.
Past Member 1 years ago

I would be supportive on all your articles and blogs as a result of they are simply up to the mark. retrofit port st lucie

Angela J.
Angela J3 years ago

Thank you.

Alan Lambert
Alan Lambert3 years ago

Fascinating information...

Pinke A.
Pinke A3 years ago

Interesting method,thank you for sharing.

Will L.
Past Member 3 years ago

I may incorporate some cob into my project too. Artists studio cottages. RV Camp ground. Permaculture food forest, aquaculture, raised beds, solar, wind, gravity feed drop flume power generation, swales and dams, ponds, earth energies from 18 th century telegraph, battery charging Stubblefield transformers.
I have held one in my hands near 50 years ago in Yukon, along the river, an old telegraph line. Thought it was a home made anchore for a pole.:) hah..surprised when I found the stubblefield not, works, develpment is on going, 500 volts in unit generates 650 volts on demand or simply keep batteries charged use converter.
12 volt appliances.
My shops, gift shop, work shops stone and bone or wood carvings and some stone jewellery ceremonial objects.
Animals are like kids..nice to have a steer fatted, nice to take off for 5 days hunting too:) We injuns, all mix up.

Erika M.
Erika M3 years ago

I've heard of it and looked into it a bit on the internet. One can make some really beautiful houses with it. I think a motivated person with experience could make a good business building Cob homes. I've also looked into straw bale building. They are both very affordable and worth looking into. I think they are also safer (basically fireproof) and cheaper to keep up.

Kate R.
Past Member 3 years ago

Cob cottages are common in my area, often with a traditional thatched roof. We lived in one for 5 years. As long as the bottom of the walls are built with stone, to reduce rising damp, & the eaves have enough overlap to stop rain hitting the cob surface directly, a cob house will last virtually for ever. I actually helped a couple of friends build a cob shed about 20 years ago. None of us had any experience, they bought a book on cob & designed it themselves. It was hard work, but fun, & a great way to spend a few hot weeks in the summer. Mud pies for grown ups, what could be better? I remember a great deal of beer being drunk & general hilarity all round. It's still standing, although I understand it's scheduled for rethatching this summer. BTW, we live in an area of high rainfall & relatively high humidity (the grass stays green all the year round)

Ashlyine B.
Ashlyine B.4 years ago

I absolutely feel delighted once I realize articles appropriate to my work and my subject.
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