Cost of Building with Cob

Michael G. Smith has a background in environmental engineering, ecology, and sustainable resource management. In 1993, along with Ianto Evans and Linda Smiley, he started the Cob Cottage Company, a research and teaching group focused on reviving and improving traditional forms of earthen construction. He is the author of The Cobber's Companion: How to Build Your Own Earthen Home (Cob Cottage Co., 1998) and co-author of The Art of Natural Building: Design, Construction, Resources (New Society, 2002) and The Hand-Sculpted House: A Practical and Philosophical Guide to Building a Cob Cottage (Chelsea Green, 2002). He teaches practical workshops and provides consultation to owner-builders on a wide variety of natural building techniques, site selection, and design. He lives in an intentional community in Northern California. His informative website is www.strawclaywood.com.

Questions and Answers

Q: I would love to build and live in a Cob house. I can't afford to buy a house and I hear the Cob house is cheap to build. Can anyone help me with information on how to get started? I live in Fort Worth, TX and I think these houses are just adorable. If you know of anyone who will help build a cob house or help someone get one that can't afford to buy one that would be great too!

A: The materials needed to build the walls of a cob home - clay, sand, and straw - can indeed be very inexpensive. However, remember that the walls are only a small part of the work and materials that go into a house. In a conventional house, the walls usually cost less than 25% of the total price of the building. With a cob home that proportion may be far lower. The most expensive parts of the house are the roof, windows and doors, finishes, appliances and fixtures. None of those expenses are reduced by building your home out of cob, except possibly the finishes.

Another thing to remember is that when building a conventional house, the cost of materials is generally lower than the cost of labor. In the case of a cob home, the materials can be very inexpensive but there is a great deal of labor required. Because of high labor costs, many professionally built contracted cob homes end up at about the same price per square foot as a conventional custom-built home. I would say that the value is far higher in that a cob home will probably be more beautiful, more durable, and more efficient than a conventional house, but cob homes are not necessarily cheap.

The best way to keep any house cheap is to do as much as possible of the labor yourself, or to find a work force that you don't need to pay, such as your friends, family, and neighbors. One of the great qualities of cob is that you can easily learn to do it yourself. Then you can teach your friends and family in exchange for their help on your project. To learn more, I'd recommend first reading "The Hand-Sculpted House" (Evans, Smith and Smiley, Chelsea Green 2002) and then taking a hands-on cob workshop. See www.cobworkshops.org for a listing of cob workshops all around the country.

Q: I'd like to ask if cob house building is cheaper than buying a manufactured home.

A: Cob building can be extremely inexpensive if you do it yourself. The materials for the walls are very cheap. However, keep in mind that walls are only a small cost of any building: foundations, roofs, windows, doors, floors, finishes, cabinetry and so on are typically a much higher portion of the cost. Also, if you a hire a professional crew to build your cob house, you will end up paying a lot for labor. The best way to keep costs down is to build for yourself (or using non-paid labor sources like workshops and work parties) and use as many salvaged materials as possible.

Q: I am from the Philippines and I would like to learn to apply natural building techniques such as cobbing and use of earthbags to our farm. I would like to apply these to buildings we would put up in our farm such as storage facilities for equipments and crops, livestock shelter and a farmhouse. For now, the immediate need is to apply natural building techniques to housing designed for livestock raising, specifically hog fattener production. I know that given proper construction tools and techniques, cob houses and earthbag buildings are superior than conventional ones in terms of cost efficiency and how these structures can withstand stress. So I would like to ask for your advice on which is more viable and cheaper for our immediate concern, that is housing for livestock raising: cob building or earthbag building?

A: Either cob or earthbag building could be good options for you. It is hard to say which would be appropriate without knowing a lot more about your site, climate, soils, and other conditions. Both can also be very inexpensive, again depending on local availability of materials.

Q: Recently I stayed in a cob house (see picture-skymeadowretreat.org). The owner mentioned it was built by people who were doing a project in learning so it was free. I have an acre of land in the Adirondacks in Upstate NY. Since loosing my job, home, etc. in CA, I'm living in my car with a paralyzed dog and trying to get creative about how to get shelter. How much is a small cob house with a wood stove? Are their programs where I can have one built? Are there payment plans? Any suggestions?

A: A cob house can be very inexpensive if you build it yourself or have a source of unpaid labor. Some tiny houses have been built for as little as a few hundred dollars (with virtually all of the materials found or salvaged); several thousand dollars is more typical for the materials cost of a tiny, un-permitted cob house. A good way to get some of the work done for free is to sponsor a cob workshop to work on your home. You will have to find an experienced teacher willing to work in your area. Usually the best way to do that is to take a cob workshop yourself, to establish a relationship with the instructor and to educate yourself about what is involved. You could do an internet search for cob workshops or go to cobworkshops.org or nbnetwork.org. Be aware that even if you partner with a cob teacher or school, there will still most likely be plenty of work for you to do beforehand and afterwards. I have yet to see any building get finished in a workshop.

Q: I stopped by your cozy little cob house and would like to know roughly how much money you have spent building it.

A: (Benjamin) I would say that the house alone was $4K to $5K. That was mostly because I had to by all the sand and clay. Also the solar power was expensive. In Oregon, Yanto Evens built a house for $500, which was quite amazing and comfortable.

Q: I live in San Antonio, TX. I'm just learning about cob homes. Before I get my hopes up too high I need to know what the cost, for example the traditional home, would be? I'm a registered nurse and I've been approved for 125k loan.

A: It's very difficult to answer your question with any precision because so many factors effect the price of a house. Contractor-built cob homes often seem to come out in about the same price range as a more conventional custom-built home around the same size in the same geographical area. This is because although the materials cost for a cob home can be substantially less than conventional materials, the labor can be more. Some contractors are able to lower their prices in a variety of ways, including by providing some of the labor for free, either through workshops, work trade, or owner contribution. The real potential of cob and other natural materials to provide very cheap housing is when the owner takes over much or all of the job of building her or his own home. That way, most or all of the labor expenses can be eliminated. Cob is an especially suitable technique for this approach because it is so easy for inexperienced builders to learn.

Q: In strawbale building, it seems as though our cost for construction are going to be around the same as if we did standard construction since most areas require the straw to be non-load bearing. Do you have any suggestions as to how to reduce the cost of using strawbales or is COB really the only way to go cheaper?

A: There are two major ways to reduce the cost of your building. The first is to make it smaller; the second is to do a lot of the work yourself or using free or trade labor (such as through workshops, work parties, or the like.) If you are paying for all of your labor and materials, the cost of your building will be fairly similar no matter what materials you're using. I'm surprised to hear that "most areas require straw to be non load-bearing." Even here in California in a Seismic zone 4 we can permit load-bearing straw bale, so I expect you could there too with the help of a cooperative engineer. You are likely to need an engineer's assistance for a large commercial cob building as well.

Q: I know you work mostly in the States, but what would be your rough estimated cost of building a 3 to 4 bedroom Cob home in the Caribbean. The majority of the materials and labor would be easily available locally, what I am concerned about is the cost of a builder to help with design and to see the project through. Can you give me a figure that I can work with while I'm in the planning phase.

A: I wish I could be more helpful in answering your query. Ianto's favorite reply to the question, "How much does a cob house cost?" is "How long is a piece of string?" I have seen cob houses built for anything from $5 to $200 per square foot. The biggest factor effecting this range is the cost of labor. I have no clue at all what the going rate would be in the Caribbean. Even within different parts of the States the going rate of labor, skilled and unskilled, can vary by a factor of 2 to 4. The other huge consideration will be the level of your own skill and expertise and how much unpaid labor you can mobilize. I would encourage you to try to find a competent builder first and have that person come up with cost estimates. That is the standard practice in custom construction.

Q: I am a husband and father of 3. I work at a minimum wage job in Georgia (specifically south Atlanta). I am going to acquire a few acres of land. The land will take most of our savings (only like $6,000 in savings) so we want to build a the cheapest house possible. We like the idea of cob, but being as we are very young and very ignorant to build our own home we need to know what kind of costs per sq ft is reasonable to assume.

A: Costs for cob homes are extremely variable. The big factors are: how much of the labor will you do yourself vs. hire out? How many materials will you buy vs. harvest yourself or salvage? What level of finish are you looking for – rustic or luxurious? Depending on the answers to these questions, and whether or not you are required to get a permit and build to code, the cost per square foot could be anywhere from $20 to $200.


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