This summer’s adventure was a two-week hands-on natural building intensive workshop at Wanosh Forest Gardens in Willits, California. The main instructor was Michael G. Smith of Straw Clay Wood and Spreadwing Farm in Rumsey in the Capay Valley; with Avani Leitz and Viva Hansen also teaching and overseeing much of the work.

I’ve been wanting to learn more about natural building since I first moved to Davis in 2012 and became aware of Michael. It took me 11 years to finally make room for this experience in my I life and I was worried my body wouldn’t hold up to the intensive daily labor. But hold up, she did!

The highlights of the workshop for me were organic, mostly vegan meals prepared with love and intention; learning a plethora of different techniques from the Larsen Truss to earthbags, concepts like passive solar, thermal mass, and insulative versus conductive materials; and, finally, the gatherings, field trip to the beach, closing celebrations and ceremonies, jam sessions, and dance parties. Capturing the full feeling for you would be a challenge.

Luckily, my main intent is to convey the most important lesson learned: currently a rarely used set of methods and materials, natural building holds great promise for constructing low cost, ecologically sound, extremely low operational cost shelters.

Michael’s first foray into using forms for a rammed earth structure which will have exterior insulation, all resting on an earth bag foundation. Courtesy photo.

What is natural building?

According to Wikipedia: “The basis of natural building is the need to lessen the environmental impact of buildings and other supporting systems, without sacrificing comfort or health. … A natural building … focus[es] on durability and the use of minimally processed, plentiful or renewable resources, as well as those that, while recycled or salvaged, produce healthy living environments and maintain indoor air quality. Natural building tends to rely on human labor, more than technology.”

The Wikipedia entry quotes Michael right up front: “As Michael G. Smith observes, it depends on “local ecology, geology and climate; on the character of the particular building site, and on the needs and personalities of the builders and users.” To quote Michael from his 2002 book, “The Hand Sculpted House,” “natural building implies profoundly different attitudes to places, building sites, ecology, work, and how we live in buildings. Natural building means paying more attention to all the details of how the world really works.”

Primary materials include cob (a mixture of straw and clay and often sand), straw bales, adobe bricks, quarried or field-gathered stone, gravel, bark, willow reeds, unmilled timbers, milled lumber, bamboo, plasters of various sorts, and used bottles. Concrete and plastic can have their place, but definitely do not dominate. Tools are primarily hands, feet, shovels, a “cobbers thumb” and various plastering trowels, but equipment as carbon intensive as backhoes can be very useful on a selective basis as well.

Despite the reality that many natural buildings are often quite small and single rooms, they can also be large and can always include conventional plumbing and electrical utilities, and all sorts of roofing systems and code-compliant foundations — all essential elements for the kind of home we’ve all come to expect. Full Belly Farm in the Capay Valley is home to a two story straw bale beauty with all the bells and whistles!

Adobe bricks made from on-site soil were used in a cob structure after drying in the sun. Courtesy photo.


This rammed earth structure was built with a set of forms that were filled, removed, then set on top of the previous run, with spacers that doubled as anchors for eventual exterior insulation. Courtesy photo.

Low impacts and learning opportunities

Natural building is labor intensive, which is the main reason it might cost more during construction than conventional methods. On the flip side, according to Michael, conventional construction generally backloads its costs, with 25% up front for construction and 75% over the lifetime of the structure for “operations” (mostly heating and cooling). Natural building projects also produce far less emissions than conventional ones due to an emphasis on site available materials, natural materials, and thermal mass, insulating, and passive solar techniques.

Michael is the author and co-author of several books on natural building techniques. His most recent work, “Essential Cob Construction,” available January 2024, focuses on giving engineers, architects, designers, contractors, and owner-builders what they need to construct code-compliant, low-embodied carbon, and fire- and earthquake-resistant buildings from cob – a mix of clay, sand, and straw.

Yes, that’s right, there is code for cob! To date, California has adopted code for straw bale and light straw clay construction but not cob, despite the International Code Council adopting a model into the International Residential Code in 2021.

Michael will be teaching another workshop this summer at Wanosh, “The Arts of Natural Plaster,” with legend Athena Steen, from Monday September 18 to Friday September 23. Topics include wall preparation, straw-clay base plaster, clay and lime finish plasters, and more.  Week two from September 24 to 29 will be taught by Viva Hansen and Blair Phillips.

Get more details here:

Since 1993, Michael has taught well over 100 hands-on natural building workshops, ranging in length from day-long oven building workshops for kids to twelve-week professional trainings. Many of the workshops are about a week long. Workshops are a great way to kick-start a natural building project with an expert leader and a group of enthusiastic helpers. They are also a lot of fun and often lead to lasting friendships.


Aspen, John, and Sasha, with Carina looking on, work together to fill earth bags to create a level run for the foundation. Courtesy photo.


Taylor with buckets of big smiles and “Chuck” (Jose) always having fun. Photo credit Leslie Crenna.


Viva Hansen sculpts a sun into a round window opening amdist blue bottles embedded in a combination cob-and-adobe-brick structure with quarried stone foundation and timber roof. Avani Leitz and Ana work on the framework for a woven willow highlight. Courtesy photo.


Yolo County is home to more than one natural building pioneer

As part of my follow through on this thread, I checked in with Jon Hammond of Indigo Architects and discovered that Jon, principal with Indigo Architects on 5th Street in Davis, has had a lifetime relationship with natural building. Davisites know the Dairy Queen wavy-roofline-conversion that is now offices for Indigo Architects and RepowerYolo, but other projects include Jon and Sayako’s home west of Winters, benches at the Davis Amtrak station, the Riverbank Teen Center in Stockton, and two police stations in Visalia and Dublin, all projects that make use of natural building techniques and materials—in particular, straw bale.

Steel, bricks, and concrete are carbon intensive building materials. Straw bale, on the other hand, is a great insulator, and when plastered is very fire resistant. One of Jon’s ADU straw bale projects survived a wildfire! Jon thinks of natural building techniques as “super beautiful” and definitely carbon sequestering. He noted that natural building is cost effective for owner-builders using the “friends and family” model, but that individual residential designs intended for general contractor-led projects have been less commonly pursued by his clients. What folks may not appreciate up front as part of a natural building construction project costs is the low operational costs later.

Jon related that the Visalia police station project used rice straw bales which appealed to that community of farmers who especially liked the idea of using an agricultural waste product. He said rice straw gives them grief because either it has to be burned or turned into the soil with external treatments because the decomposition process uses a lot of nitrogen. So rice straw bale-based structures are a win-win for sure.


Jon Hammond of Indigo Architects constructed the first modern-era strawbale structure in the early 1980’s in Winters, California. This home sparked reinterest in the use of native and low-energy materials in construction. Strawbale creates charm and energy efficient R-50 walls. Integration of sculptural elements and traditional forms into a straw bale house create an expressive and super insulated architecture. Photo courtesy Indigo Architects.


Timber, straw, and plasters give a soft and warm feeling to this home. Photo courtesy Indigo Architects.


The Riverbank Teen Center in Riverbank CA features: Strawbale Walls, Large Roll-Up Doors That Create a Free Flowing Indoor/Outdoor Space, Natural Ventilation, Natural Light, Computer Lab, Workout Room and Kitchenette. Photo courtesy Indigo Architects.


The Visalia Police Substations feature: Twin buildings combine elements of Spanish-style design with practical, energy-saving materials. Thick straw bale and concrete block walls provide ballistics and blast resistance with the classic look of adobe. These substations serve as forward-thinking examples of how small towns can lead the nation in smart civic building, reducing impact on energy and resources. Photo courtesy Indigo Architects.


Dublin Police Station: This LEED-Gold energy-efficient building features the use of sustainable, straw bale construction. The structure is a beautiful addition to the civic architecture of Dublin, that also contributes to the viability of California’s agricultural regions. Photo courtesy Indigo Architects.

The potential for natural building

While much work remains to expand the reach and viability of natural building on a larger scale, and in urban/suburban settings, the techniques hold great promise for addressing our housing crisis in a manner that respects the earth and those of us who live upon it. Natural building can deliver on the promise of a safe and secure future. I’m excited to see where it leads for you!


Michael and Wanosh’s workshops and his upcoming new book are great ways to find out more. With so many books and resources out there on natural building, it can be intimidating. Focus on the resources in this article to get started.

Indigo Architects web site:

YouTube channels

Sustainable Building Essentials book series

More books

Other cool stuff to check out

Michael G. Smith of Straw Clay Wood oversees work on a rammed earth structure with forms and earthbag foundation laid on gravel-filled, sloping trenches with drain pipe. Photo credit Leslie Crenna.


Leslie Crenna (author) sets runs of adobe bricks with mortar made from on-site soil. Photo courtesy Wanosh Forest Gardens.


Leslie smiles as the wall rises standing on a straw bale to keep up. Peter works on the section near the window with outside sun sculptural element. Photo courtesy Viva Hansen.