The Double Chamber Cob Oven

Cob ovens have an incredible power – they bring people together, they bake the most amazing food, they are beautiful to look at, and they are not too bad from an efficiency perspective. With a growing awareness around air quality and increasing pressures on wood resources, we always want to make the most of the wood we burn. Rocket mass heaters have led the way in super efficient do-it-yourself heaters and it was just a matter of time before some of these principles were adapted to cob ovens.

The Efficient Update Has Happened

So yes, it has finally happened. We have a wonderful cob oven design (thanks to Ernie and Erica) that brings the best of cob oven cooking together with the benefits of a rocket mass heater. It’s found in a double-chamber cob oven and we had the great fortune of building one at a world class community greenhouse run by Groundswell Network, located in beautiful Invermere B.C. Groundswell is all about community sustainability through education, with a beautiful gardens and a four season greenhouse being their flagship projects. The cob oven would complement their efforts beautifully, bringing people and good food together in a whole new way!

A gorgeous stone base was built by several local masons organized by the folks at Groundswell. Once complete, we stepped in to lead the building of the double chamber cob oven through a 2-day workshop held in September (our basic cob oven workshops are 1-day but this is a larger more complex design).

Unlike the traditional cob oven that we build, a double chamber cob oven has 2 doors – a firing door placed in the outermost opening, the opening of the smoke chamber, and a baking door placed in the opening to the baking chamber, which is behind the chimney. The baking door could be made of solid wood (soaked in water before use to keep it from burning), or steel. The baking door serves to seal up the heat in baking area of the oven. The firing door has a cutout with surface area matching that of the total area of the chimney. This is to ensure that the air exiting through the chimney is replaced in proportion with the incoming air, thereby allowing for more complete combustion.

Side view of the Double Chamber:

Top view of the Double Chamber:

Here is what we did during the 2 – day workshop:

double chamber cob oven form

double chamber cob oven chimney

double chamber cob oven

double chamber cob oven insulation layer

double chamber cob oven plaster

double chamber cob oven with stone masonry base.

double chamber cob oven workshop

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