Going Green with Cob
Cob building has been a popular construction method for centuries. The materials used are normally within the local environment, which can help the design blend into its surroundings. Cob structures offer a lot of design freedom that only have a few limitations, one of which may end up being cost. The overall cost of the building is dependent on the scale of construction.
There are three main base materials used in cob building. Clay, sand and straw are mixed together to form cob. Now, if one had a lot of these materials already their cost would be small but the majority of people building today will need to at least buy the sand and straw to get their cob started.
The amount needed to be bought will be based on the scale of the building and the pricing of local resources. A cob home can be much cheaper to construct than a traditional home, though it is important to keep in mind the wiring, plumbing, windows and doors that will be used in the home. For our purposes here, we are just going to look at the base price for the cob construction itself.
Estimated pricing for 30 tons of clay, sand and straw can be rounded out to $500 apiece. Adding all three, the cob estimate comes to $15,000. This total is for a simple 1 bedroom, 1 bathroom construction that includes a living area and kitchen. Again, the prices depend on the area you live in and the suppliers that are available. Unfortunately, creating a static price list that spans the entire United States is not possible due to fluctuating costs in different areas of the country.
Cutting Costs Down
An alternative route to the costs above, would be to use the local materials available. Some people who build with cob have free land space available for building. Another way that people have broken down the cost of materials is by using the clay and sand already on the land. Straw can be either grown or collected from donations. People have also collected wood scraps and other left over building materials from construction sites for use as window frames and doors.
The following are items that can be used to build cheaper:
- Clay already on land
- Sand already on land
- Donated or home grown straw
- Well water on land or municipal water
- Use self and family as only labor
- Donated lumber from construction sites
- Scrap wood collected on land
- Left over sand from construction sites
These are just a few ways to cut the cost of building materials for cob. One other way would be to appeal to your local community for donations of supplies and labor. Even by using a few of these ideas listed the overall end cost can be very reasonable for self-made green construction.
The Cob Cottage Company, https://www.cobcottage.com
Adam Weisman, Katy Bryce, Building With Cob: A Step-by-step Guide, Green Books, 2006.
Image credit: The Culture Artist Orginization, Cob Building Gallery, https://www.cultureartist.org/Cob_Gallery/cob_building_gallery_page_16.htm