The Olmo Project

The driving force behind the Olmo Project was to design a wood-fired earthen oven for a specific location with a specific function. There were a few factors that came into play with the design. First, the oven not only needed to cook pizzas and breads but needed to be large enough to cook a turkey. Second, because of its location, the oven needed to have a sleek profile so it would not visually dominate the environment. So, I decided to build an experimental/ hybrid  oven with the capacity to function as a traditional "Horno" as well as an oven that can be continually heated with wood or propane. To increase capacity the interior space without creating a massive structure, I took the traditional round dome design and made it oval. This allowed me to make an interior width of 22" while maintaining a depth of only 15". These dimensions give me plenty of room to place a turkey as well as allow space for continual wood stoking. The secret is, that I build in a secondary chamber below the floor of the oven with a grate system in the actual floor. This chamber allows air regulation into the oven and can also serve as a firebox if desired. By placing a flue on the opposite side of the grate, the fire will be pulled up, across and down the interior of the oven in a typical cross draft manor. To minimize the exterior bulk of the oven, I insulated the oven core with 3" to 5" of vermiculite that is contained by a 3" high straw cob shell, topped with a high straw plaster coat. The finished product is an oven with a large and diverse cooking capacity while maintaining a humble presence.

The first Layer of urbanite determines the size & form of the oven

Here you can see the layout of the floor and grate system. I used an old iron drain cover for the grate that rests on to a internal firebox composed of firebrick.

After the earthen inner core was built and hollowed out, I inserted a stovepipe for a chimney and used a thin sheet of metal to create a sprung arch doorway.

Here you can see the results of the oval design, creating a sleek footprint. You can also see the entrance to the secondary chamber. While a small fire could be maintained inside, this opening would be best utilized as a burner port for a propane burner. It's original design plans is to allow air into the main chamber to burn wood placed inside the oven at the same time allowing a place for ash and coals to collect. Eventually a plug will be built to control air intake. By providing air into the oven, fuel can be burn cleaner, hotter and more efficiently. This also allows wood to burn with the door closed for continual stoking.

This a  Current picture of the Olmo Oven in Progress as of 1/14/06. The finished oven just received a finish plaster coat and eventually the chimney will be capped. A simple shed roof will be built over the oven, giving protection as well as creating a work space off to the side. The construction of the oven began in November, not a typical time for natural building. I was blessed with nice weather but drying has been slow. The rainy season finally has arrived so the oven is tarpped until a roof can be built. To counter act the moisture, I built fires inside the   base and interior dome to speed the drying while I was still building. The choice of vermiculite not only made a good insulation but is very lite, allowing me to finish the building on top of a still wet interior core with out the fear of it caving in.

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