Masonry Heaters, Wood-Fired Ovens, Natural Building

Wood-Fired Barrel Oven in Swannanoa, NC

A practical and wood-efficient oven built by hand from local clay, river sand and recycled red clay bricks. Project is evolving into a fully developed outdoor kitchen with counter tops, a wood-fired griddle, a sink and more! The whole area will be roofed as well. Stay tuned for more good times and stories of this family oven at Davidson Farm.

Sculpted Guitar Oven in Brevard, NC

Eva led a workshop in April to build this oven at the Duckpond Pottery, Nick Friedman and Jennifer Kelly’s retail pottery shop and venue for live original music. Nick had an awesome idea to make an oven in the shape of a jazz hollow body guitar! We harvested clay from just down the street and sand from the French Broad River. The people of Brevard are so talented and so much fun! Expect some amazing natural building projects to blossom there soon.

Bali Wood-Fired Oven

We built this wood-fired oven in Bali for Max’s parents using local bricks, clays, sands and fibers. The oven joins the traditional paon (cookstove) that Max built a few years ago.

This oven features ample wood storage for both units, a metal firing door and a wooden door for baking. (Stay tuned for an article about firing doors and efficiency in wood-fired ovens.)

It is always a fun challenge to apply our knowledge of ovens and natural building to local materials. The clay for this oven comes from a village roof tile factory scrap pile and the sand and stone came from a nearby volcano. We found an incredibly porous lava stone to insulate underneath the hearth floor and surrounded the oven’s thermal layer with a mixture that included rice hulls and thatching grass.

Note the sand used to make the smooth inside shape and the sculpted “squirrel tail” to jog the chimney. Upon finishing the oven, we cooked for a three day “Live-Culture Cuisine” fermentation workshop led by Sandor Katz and Mary Jane Edleson.

Many delicious feasts ahead!

Learn to Build Your Own Earth Oven!

Ledge Stone Masonry Heater Near Eugene, Oregon

This heater was built for a family who live near Eugene, OR.  It features a see-through firebox, heated bench and a bake oven.  The outside skin is laid with Montana Bitterroot ledge stone with Three Rivers stone detailing the bake oven arch.  We cast, poured and and polished the bench which includes special embedded stones and fossils.

The heater has a compact, responsive design which serves as a partial wall between living and dining room spaces.  It could have many different facing looks, occupies an area of 48″ x 48″ and stands 6 1/2′ tall.

Read More….

Thanks to Greenleaf Design Build for their good organization and excellent
craftsmanship which allowed our work to flow together seamlessly with their’s.

Masonry Heater at the Allen’s (Portland, OR)


We built this masonry heater in the Portland area in autumn of 2011.  Our clients had collected many beautiful bricks dating back to 1883 (a long time from our West Coast perspective!), local basalt rock, and cobble stones that originally paved the streets of Portland.

This masonry heater (based on the Swedish 5-run design) has a see through firebox, a bake oven, a three-sided heated bench, and a place for wood storage.

This project brings together our understanding of the technical aspects of combustion and heating efficiency and our experience with design and use of recycled building materials.  The heater is currently curing and the exit flue will be installed shortly.  We plan to update this post once the heater is fired and make new posts about the process of this build and about the use of polished “concrete counter tops” for benches and other elements of mass heaters.  Check back on this site, join our mailing list, and see more about this project on Facebook.

Thank you to Norbert Senf and Doug Hargrave for their development of the Norccore and for generous technical assistance in preparation for this project.  Thank you also to Jerry Frisch for continual support and inspiration.

Read more….

The Cabin Stove – A Small Masonry Heater at Aprovecho Research Center

A good part of the month of August has been dedicated to the research, development and construction of a small multi-functional masonry heater I have been calling “The Cabin Stove”.  Eva and I have both been working as instructors in the first year of the Sustainable Shelter Workshop Series at Aprovecho Research Center in Cottage Grove, OR.  The building that is the focal point for this course has been designed to be just slightly smaller than the legal requirements for permitting so that it can at the same time be a teaching tool as well as a laboratory for a basic building system that a group of associated natural builders in the Pacific Northwest considers to be a sound and ecological way of making a home.

The challenge of the design of the Cabin Stove was to come up with something that was very compact but also still resembled and functioned like a masonry heater.  The design criteria included heating the small space, an efficient and clean fire, utility for cooking, heating water, combining some quick/immediate-releaseheat with slower retained radiated heat, relative ease of construction, not too expensive, aesthetically pleasing, and being as compact in size as possible.  A very interesting process to try to combine all of these together.

Our test firings of the prototype in our shop were very promising.  The fire burned well and had no problem making its way through the longer pathway, even notably when the door was open with the beautiful cast fire screen reducing the overall air intake to a moderate amount. I think the design meets most of the criteria listed above well with the exception possibly of cooking utility since this was compromised to accommodate other features.

For the initiated, it is basically a very compact J-loop contraflow with a bi-pass that runs directly to the flu and allows it to function even as an open fireplace.  Rather than insulating the top of the heater as is done often in masonry heater construction, there is a 1/4″ steel plate placed on top that serves as a cooktop and source of immediate heat.  I am optimistic that the proportion of immediate and retained heat will be a good one for our bio-region where temperatures can fluctuate greatly during the day and from one day to the next.  We are within but on the outer limits of the kind of climate that masonry heaters were designed for which explains the need for continued development and innovation.

I did notice in firing the prototype that the big steel plate I had placed on it arced noticeably when hot so I welded a 3/16″ frame onto the Cabin Stove we built at Aprovecho though I am quite sure that the heat will play its funny games and have its own way with the final shape of the steel plate.  Cast iron is almost certainly the way to go for the top although I do not know of a source of affordable custom sizes.

Although the heater at Aprovecho was designed to be a double-skinned heater with a compressed earth block and local stone veneer, I am very excited that we will first test the heater with a single skin.  A neighbor has offered to lend his carbon-monoxide and air-quality monitors to test whether there are any dangers that result from expansion cracks in the single skin.  Given our climate in Oregon, the prospect of building responsive single skin heaters is a very interesting one.  (Note: the variation in the firebrick is because we used firebrick out of an old heater that had been taken down.  The students re-milled each brick to cut away the old mortar to return the brick close to original dimensions).

I have recently been very inspired by the Open Source design philosophy so I share the rest of these photos of process in that spirit!  Stay tuned for more on this heater and other research and endeavors.  Click to see any images enlarged.

You can see some other details of the building, including one of the timber frame’s posts; the faswall and stone stemwall; and strawclay insulation packed in between Larsen-truss style framing.

Custom-made heater hardware, made in our shop from scratch.

Details of Hot Water Serpentine.  More on Plumbing for Thermosiphoned Hot Water Systems….

The light and surrounding forest were really exquisite when I took these shots of the veneer material.  The compressed earth blocks were made by the students.

Find out more…..

Outdoor Kitchen at Vistara: Wood-Fired Barrel Oven and Canning Stove

Ever dreamed of an efficient earthen oven that was hot in just 15 minutes?
How about a canning stove that could process 32 quart jars at once?


The new Wood-Fired Barrel Oven and Canning stove at Vistara!
Built with students during the Outdoor Kitchen Workshop Series!

These two cooking devices will soon be part of a full kitchen with shelving, a sink, wood-storage and more!  They will be connected by counter tops and sheltered by a roof providing ample space to prep and to gather. This will be a resource for the local community!

Vistara has a beautiful garden and many neighborhood fruit trees from which to harvest abundant produce to preserve.  The wood-fired canner is quick to heat up and can also double as a soup pot, stew pot, sauce pot, steamer, etc. Both the barrel oven and the canner were constructed with homemade adobe bricks and plaster formed with Vistara’s clay rich soil.  Thank you to our hosts and the amazing team that helped make this happen!

 Find out more about The Wood-Fired Barrel Oven.

Complete Cob Workshop at Cob Cottage Company – Bandon

Jun 11-19, 2011 in Bandon OR

Max & Eva taught a 9 day intensive course called Complete Cob.

Our project was to build a pavillion that is a large part of a budding outdoor kitchen at the home of Bob and Tammy Van.  During the nine days, we sculpted this structure with local soil, driftwood, redwood and found windows. The course covered in depth all aspects of cob and building techniques such as foundations, construction of walls, arches for doors and windows, roofing, plumbing, electric, shelving, furniture, earthen floors, artistic details and finish work.  In addition to the outdoor kitchen, Bob and Tammy wanted to renovate their garage into a meeting place and so we also worked with them to remodel their existing stick frame construction with ladder trusses and the participants mixed and installed light straw clay insulation.

Added bonuses were the rumford fireplace we built in the pavillion and plastering the new Cob Masonry Heater at Cob Cottage Company!  Our course also covered general natural building strategies such as siting and passive solar design.  We had a beautiful time and are so thankful to our generous and talented hosts!

Making the model

Building and Carving

Windows and Arches

Shelves and Chiseling

Ridge Beams, Rafters and Lashing

Making a Rumford and an Earthen Plaster on the Cob Cottage Masonry Heater

Making a Beautiful Outdoor Kitchen!

The Cob Pavillion with Rumford Fireplace

More photos of the finished roof, plaster and the straw clay retrofit coming soon…

Written by in: Latest News,Natural building |

Straw Clay Retrofit – Village Building Convergence 2011

This year at the VBC,
Eva led the second phase of a light straw clay retrofit in SE Portland
at the Planet Repair Institute!

Light Straw Clay technology has been used for centuries!
People love the low cost, low toxicity, and its use of sustainable, native and locally available materials!

Over a ten day period, with hands on learning, I taught students how to make and use straw-clay effectively and efficiently to build insulated walls.  (See also last year’s post.)

Participants learned about Larson truss framing, and the many facets of mixing and installing straw clay and cob for both interior and exterior settings. We all enjoyed the incredible benefits of this natural building technique as we retrofitted a previously poorly insulated Portland home! I returned later with students to put a base coat plaster on all the walls. Next year at the VBC I will lead the finish plaster, aliz, and sculptural details on this project with Molly Murphy of the Mud Girls.

And good news!  Light straw clay has now been approved by the City of Portland!  This is Portland’s pilot project!  Click here to see the info from ATAC about permitting this technique...

More about the Village Building Convergence…
More about the Planet Repair Institute…

Join our mailing list to receive updates about the finish plaster and more!

Written by in: Latest News,Natural building |

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